Yi Wye i 7 We i ————= —— : 2.21 a''a ‘aia’ a @ .2'818°8.0. 074 DAD. B.S OB AA Aa A eae > ee rey aR he FN > dz Sey 6 ~ a ioe i a es / é iy 4 = 2 = a is a : ‘ee 3 Sasexeteite: a 4 iB: . AZ no & igen CP ESM OO 72 ap — ee ~ re ME see \ OTST hes Pan ( nny Dah rt AM ented 4 Vy RATE AW RAN {ys a i ty ghey 4 PN ECHR Fase ia : MRE ANY | RNS JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY; CONTAINING ITS TRANSACTIONS AND PROCEEDINGS, AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BOTAN YD (principally Invertebrata and Cryptogamia), MICROSCOPYW, Sc. LIBRARY NEW YORK Ldited by BOTANICAL GARDEN FRANK CRISP, LL.B. B.A, One of the Secretaries of the Society and a Vice-President and Treasurer of the Linnean Society of London ; WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND A. W. BENNETT, M.A., B.Sc., F, JEFFREY BELL, M.A, Lecturer on Botany at St. Thomas’s Hospital, Professor of Comparative Anatomy in King’s College 8. O. RIDLEY, M.A., of the British Museum, asp JOHN MAYALL, Jon., FELLOWS OF THE SOCIETY, ser. fl—VOL. lls PART 2. PUBLISHED FOR THE SOCIETY BY WILLIAMS & NORGATE, LONDON AND EDINBURGH. ESS 2:, The Journal 1s issued on the second Wednesday of February, April, June, August, October, and December. Phy ; $ Bic Ser. II. : To Non-Fellows { Vol. 11. Part 4.} AUGUST, 1882, |" Price 48. JOURNAL OF THE | MICROSCOPICAL SOCIETY; CONTAINING ITS TRANSACTIONS AND PROCEEDINGS, AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BOTAN YT (principally Invertebrata and Cryptogamia), MICROSCOPY, &c- a —, Edited by FRANK CRISP, LL.B., B.A., One of the Secretaries of the Society and @ Vice-President and Treasurer of the Linnean Society of London ; WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND _A. W. BENNETT, M.A., B.Sc.,~ ¥F, JEFFREY BELL, M.A., Lecturer on Botany at St. Thomas's Hospital, _. | Professor of Comparative Anatomy in King’s College, $0. RIDLEY, M.A., of the British Museum, ssp JOHN MAYALL, Jex., , FELLOWS OF THE SOCIETY. ' WILLIAMS & NORGATE, : : LONDON AND EDINBURGH. . PRINTED BY WM. CLOWES AND SONS, LIMITED, } {STAMFORD STREET AND CHARING CROSS. C2) JOURNAL OF THE — “ROYAL MICROSCOPICAL. soommry. Ser. 2.—VOoL.L. Ile PART 4. (AUGUST, +BB2) Cun iers TRANSAOTIONS OF THE: SooimetTy— 2 < rae oh oe PAGE X.—On some Micko-oRGANISMS FROM “Ravwarm low aa Ham. pe bets By R. Li. Maddox, M.D., Hon. F.R.MS;&. .. 2k. 449° XI.—Tae Repation or APERTURE AND Powsr IN THE Mronoscorr ; (continued). By Professor Abbe, Hon. F.R.MLS... .. .. 460 X1I,—Descrierion or a Suupia Pray or Impeppina Tissuus, For Microtome Curtine, in Semi-punpep Unenazep Printaye Parrr. By B. Wills Richardson, F.R:CS.L, Vice-President _ University of Dublin Biological ‘Associa PAE he anes ece NM Shy. Le Bie XIL —NotE on THE Rey. G. L. Mus’ PAPER on Diaroms: ji. Nes Peruvian Guano. By F. Kition, Hon. F.RMS... .. .. 476 Summary or Curzent ResEARCHES RELATING TO ZooLoay AND Borany (PRINCIPALLY InvERTEBRATA AND Cryprocamma), Micro- scory, &c., INCLUDING OniGinaL Communications: FROM FEutows AND: OTHERB. "oS. foc) wa 26d SS es coy eat > ee ieee ea eae eS. _ ZOoLoey. Sep ee OR BaP aD Division of Embryonic Cells in the Vertebrata, 2 s00 2 Si Des gure Pam 7, ATS Genesis of the Egg in Triton .. —.. eerie, risiry yy Sane Bryce 7 Rage Formation: of Bibrine se) sed ide) we hse se Mae vo tp ae eee ina ee Bi pale New Blood-corpuscle . en eee A RRR io eons MRR aE OD Life and Death in the “Animal Organism .. Jo Wika eet wt heh Gemeeieed Cast FS Pelagic and Deep-Sea Fauna ., sede aS phea tae Ne Gad tebe A es tL: Anatomy and Classification of the Cephalopoda LORS eas A ee gee eae ES Ink-Sac of Cephalopoda .. _.. +: oe beet obats gay ae oe Og. Sense of Colour in Cephalopoda es Pipenmeninie, mkt F-sceary a yee ible tS ‘ Foot’ of certain Terrestrial Gastropoda PE SMS kG IT eRe Te Mucin of Heliz pomatia .. .. wee ER age 0k apes Mike wipe itr tatet eet Rhodope veranii .. — «. Be Fr abies) GEM CK Beli chibe SMS RMI ia hele ae En Vest.Cells%in Ascidian.Ova SL meen earn are IPSS S wicstam I a Embryology of the Bryozoa Paes eee Pa ae Tamar y HUE ahs eran: ee Nt ty New Adriatic Bryozoa«. iF eel, SOE Sensations of Sight conveyed by ‘the F aceb-eye @ igs 88 aad i) Pe oe |) ae Nervous System of the Strepsiptera.. «. as ver ae) 499 Insects which injure Books VR ae oe ee alan A PENRO ECO PEM ee ae Ra ROD Formation. of Galle: oe i iyioe ter mabe ad aby Vola Chat eda tae es Anatomy of Phalangida .«. reer ty aaltes et AS) | 5 Aree Scent-glands of the Scorpion-spiders (Thalyphonas) PGi ne Satm tchios Metab aera tee, Classification of the Brain of Crustacea...’ .. Bb da ye en a agen oe Unpaired: Bye of Crustacea): 50)... oar ay ees ian) ole) aa eee PE Blood of the Crustacea... Bago igs Sg gh A a aE ee Pyloric Ampullz of Podophthalmate Crndacea se sh pee - 805 Heterogeny of Daphnia. 2» es ewe tee te ae wn a 906 i ee a eee RAE HBS MK = ‘Summary or Current Resmarones, &c.—continued. : PAGE : Notodelphyide .. (ARS Sita ie A 506 rare Organization of Trilobites .. UG Tones SORT Ta oO Tet Papel Set Chemical Composition of Tubes 0 af On Onuphi He SNES ey hey eee ROT RR Nematotd Hematozoon from a WILE Ae ESOL ee SERS oe OM Development of Marine Planaria: .. + ee te pete te ne we BOD Eyes of Planarians .. SAR Mahe Se PMRCONE Lte hee Q he Sek LO Development of the Orilionectida. Sie GaN SGN Se Rad ORR AS aiaae TAR ei , Byes of Rotifers .. .. as 65 EN See One ata eo DE ge ees Cee Ee Anatomy: of EHolothurians: 3. ise 58 eek. fee tap tees anes ey, ee OAS Hybridization of Echiinotdea 4+ ss ee ee ne ne pe we ee ne BIB Variation in Asterias glacialis ... .. CVE be eke cow OLS ~ Development of Calcareous Skeleton of Asteroides - PPE Sr a RUE ELC RUS) 3 Development of Ziquorea .. RIESE rial amass IR PETe GL eee Fi) Hybridization in Fresh-water Sponges UR Seer UNE i Py he ees Boring Sponges Barrie § Cae pee N aw Neal? oa. t Rae RS aN RRR, eee OLO De Lanessan’s Protozoa .«. SEU y dys Rage Peipaning ait ipta, ad one e mundo Kents Manual of the Infusoria es, SREP sae gt SE ERO eee IR Flagellata .. ies Ae OLS Cell-parasite of Frog’ ¢ Blood and Spleen (Drepanidium ranarum) SAR ieee Sy Development of Trypanosoma... «+ +. Dae, Pett aby Spee UOeD : _ New TE GOUPINAE Ge ek had SR oe ae aa Seg PAP pee Nance ae Oe Chemical Difference between Dead and Living Protopasm (Fig. es +» 522 * Killing of Protoplasm by Various Reagents .. ¥ Sek em ree Apical. Cell-growth in Phanerogams..0 6 ek ne te ee oe ee we 528 Development of Bordered Pits .. Se ene TOee ‘Development of Tissue as a Characteristic of Groups of. Plants same aeY | Stomata of Polycolymna Stuarti .. Pee ep ae HOE Properties and Mode of Formation of Duramen .. sl ft be oer) OD History of Assimilation and of the Functions of Chlorophyll PARRY Theoretical View of the Process of can zie og fviga. ew n dae _ First Products of Assimilation... — .. Sects (om Subba ee NP RS anh eae ae - Absorption of Metallic Oxides by Plants... 526 Decomposition of Calcium carbonate tn the Bre of Dieters Woods 527 * Hypochlorin.. .. oe big ak Sales sole Sooke (aes ORS - Latex of Euphorbia Lathyris a ges) ag ee OSE Darwin's so-called “ Brain-function: ” of ‘the Tips of Roots « oR a RaRA edt hee. OGD Aerial Cultivation of Aquatic Planis' .. pe Saat phi pe ye Seon TNGerlecOrOUs: LLGMtA Seve. vege iube oy ate oar EARS A AAS IESS Oe ee) OBL Climbing Plants ...:. bit Re GR ww ety s 12S Sap ce hy ae Ae ls ope RPE Power of Movement in Pigteis \ Siskaeo Sia ae si ep Sk: Nr Pied er bee ODE Electrical Researches on Plant Forms... Seat neya ee WN ee ate Oe Electromotive Properties of the Leaf of Dionza .. x dee dette shea woe ~ Influence of a Galvanic Current on Growing Roots... ws ee ee 583 Schizeacee .. . SO AP Seah a che She tack Oh lasek A TRAN OR Branched Sporogonium of @-Moss .. ee ee ete en Tr aeoer tae Influence of Light on the Thallus as Maréhantia. SS eaety ave OEM Oe RENN «5 Goebel’'s Musciner — .- Fite CW IRS ped Shee pk ae Doe Development of the Cortez Si Ohta ce Sgt gS ey GN OBB Ustilaginer.... ir raS ek ts st Aiadas a ste ig lo. by we OG Unobserved Sensitiveness in Phycomyces Rae Oba t ans Guan as TE CaaS gan pe OD Beltrania, a New Genus of Heghomyeates Pa ah aaa ait ier Ur Se Chemical: Composition of aes * Pees ahr ae Visie te a eek, OUR Salmon Disease... «s 538 Formation of Saccharomyces in - Nutrient Fluids containing various Pro- portions of Nitrogen .. han hues ve, SSE Morphology and Genetic Relationship of Pathogenous E Bacteria... 1. 541 Bes - “Pathogenous Bacteria... °.. Boe DS ves Mae sR Tec 2 Rak 3 Bacterium of Charbon .. he! apeedp ate) ag aaa ve TC wok URS ee pa Pe Connection of Bacteria with Ferments Mane teey 2 hak sake or ug eats Gar base taek SE Life-history of Cora... sR pak s Tete ete) ulus eles te ces t kaeee Minks’s Licheno-mycological Symbols ib EUR PRT Spee Sle ae ak arya c the Symbiosis of Alge with Lower Animals... 2. ee tee ae we ee, 4D Division of the Cell-nucleus in Spirogyra ogres PME GHy aes Sends LORD (ay ‘Summary or CURRENT Reseanonns &e—continued. PROCEEDINGS OF THE SOCIETY phi ace aieh NIB eee goat eee 549 ae 909 O78 BI 878 aT: Pi aoe PAGE. Batrochospermimn |. 0 OC a eon eck ae eee tec Oe iene tae CAE New: Beg geet. os te a OR EP Ie pti ay Saat ay een HEA (MGM YP EN a on Soe Mea Eee Cn, as oe a ae Sede he ee epee ae OE Schizophyces. SANT We OF askin: hae seine Oa Sa ReMi aint ee OURERS me ae i neem aes OME Ly Mobionaf Diabaig: 252. GO gh POL ag a oe sae eg ee : Microscopy. Pei g sir: ae Re Lossner’s Tele-microscope .. .. Lk ON Jae og eh aia! DEE Prazmowski’s Micrometer Microscope (Fig. 91) ee erg th Simplified Reading Microscope for horizontal and vertical sive ROW Nea, Swifts Tank Microscope (Fig. 92) .. Rapier etree. Oa Leasdale's Field Naturalists Mieroscope (Figs. 93 and 94): bce Trae S Nes, BESET Steinheil’s Achromatic Eyepieces (Figs. 95 and oy Si Vides Mawel ales Aiea «eka New Combination for Objectives 2. uae Gah SGth saana aay tue et RO DE. Fluid for Homogeneous Immersion .. Sol Shurley’s Improved Slide for the Examination of Gaveo Dialer Orig ” 551) Hardy's Compressorium (Fig. 98) -... 4. ws aaa hae Rane ee Bulloch’s Diatom Stage ~ .. Soe aa Re aden eer rede Substage Fine-adjustment (Fig. 99) .. Rae atno Pancreas ee ee at ES Sidle’s Centering Substage (Fig. 100) ied aps OOS Mounting for the “Woodward” Brink (Figs, {01 and. 102)’. magnesia rh ag 3H Prisms versus the Hemis; herical Leng as LUNN ie AOD nae ues 4 Pate 3411 Hadial Tail-pieces’— .. em ear cael wey y Electric Light in Microscopy Pigs 103 and 104). TERCERA ek OEE Black Backgrounds .., pets epi ey Apa se BO Micrometrical Measurement by means “of Optical Trages OF eh a irs Be aay ~ Malassez's Improved Compte-globules (Figs. 105- ae her dat haipeeanaarat Cutting and Mounting Microscopical ones Bao bh hae k BOL ay eee EE Preparing Blastoderm of the Chick .. se. 41 ee eu ee te te ea TO Preparing Embryos of Insects .. *. eb Yale SN Ree eae iaabac Ce Collecting, Staining, and Photographing Babteria say Cc ee eee OTL Ehrlich’s Method of Exhibiting the Bacteria of Tuberculosis Wi fyam Siders DIS Preserving Infusoria and Amebe 6. te cee ne ee eee TA Preserving Protozoa. .. Cae “a ahe eA eee Bac tae ne Ege Staining the Nucleus of Living Infusoria... PR ey tee eet Mr Lan em Double Staining with Carmine and Anilin Green .. Ry ied eRe egies AOE Cutting Sections of: Coal: vi) 5. Sa Gal Say eae ee wa ee a ONE Bections of Miea-sohiiat 56a eee, a an ae eee etee. OTS Paper Cela riot oe ags® ook icp ae pix decal eae a el ga ane ike eel ea Wax Cells ne ae . oe SAE oe Rk we pat 5 ee ae bacpcare cur 578 Miller’s Caoutchoue Cement. sss es tn ae Mounting in Phosphorus ee aham nie gang Seal on eikan Naas eee eee Vacuum-bubbles in Canada Balsam . Pea Nias i WR Soin Sh RIO OA Patt eR ole Mounting Moist Objects in Balsam. jodi) aan gs alga aw © toe chee eek (DOA | Moisture in Dry Mounts’ .. °.. as Sa pV gE A Ge ea ea Dammar Varnish j yb 60 enw iy Sy te neon ae eee Oe Cleaning Used Slides and Covers oUg og ol Eadie” aah hE Cae ay RE AI BE Resolution of Amphiplewra pellucida... 24 ce ce ae ne ak ne ee BEY Microscopie Examination of Wheat -flour .. x5 ine Weds 3 pe etek DOS Destruction of Microscopical Organisms in Potable Water ye We tga on 2 OOD. Public Lectures in. Microscopy *+s 55 os. a a ke he nee ae 585 589 (8) AHopal Aicroscopical Society. “MEETINGS FOR 1882, . AT 8 P.M. 1882. Wednesday, January... 6. we % FEBRUARY .. sein § (Annual Meeting for Blection of Officers and Council.) us Marcu 8 Be APRIL .. 12 y May | 10 5 JUNE 14 be OcTOBER FOS SIERO Peake Bs OMe Supe > | 5 NovemBEeRr . DeowMBeR Hi Fe Se PAS THE ‘SOCIETY’ STANDARD SCREW. The Council have made arrangements for a further supply of Gauges and Screw-tools for the “ Socrery” Sranparp Sorew for Ossxorrves. The price of the set (consisting of Gauge and pair of Screw-tools) is 12s. 6d. (post free 12s, 10d,). Applications for sets should be made to the - Assistant-Secretary. For an explanation of the intended use of the gauge, see Journal of the Society, I. (1881) pp. 548-9. ADVERTISEMENTS FOR THE JOURNAL. Mr. Cuartes Burncowsg, of 75, Chancery Lane, W.C., is the authorized Agent and Collector for Advertising Accounts on behalf of the Society. (6) “COUNCIL, ELECTED 8th FEBRUARY, 1882. re PRESIDENT, : Paar. Pe Marin Duncan, M.B., F.RS. ~ VICE-PRESIDENTS. Pror. I. M. Baxrour, M.A. E.R. S.. . Rosert Brarrawaire, Esq., MD. MBC. S., FL, g. Rosert Hupson, Esq., E.RS,, ELS. JoHN WARE STEPHENSON, es BRAS. a TREASURER, Sa Lions 8. ‘Beare, Esq., MB., FRCP, ‘ERS. SECRETARIES. OHARLES Srewarr, Esq., MLR.CS.,. FLS. oe Fran Crisp, Esq., LL.B., B.A, VP. & ‘Tras. Ls. Twelve ather MEMBERS of COUN cI. Lupwie Dreyrvs, Esq. CuAaries James Fox, Esq. Jamus: GLAIsHER, Esq., F.R.S., PRAS. J. Wirt1am Groves, Esq. A. pE Souza Guimarazns, Esq. Joun KE. Inaprn, Hsq. Joun Mayatn, Esq., Jun. Aupert D, Micwazrn, Esq., F.L8. ; JouN Minuar, Esq., L.R.CP. Edin, F.LS, Wii1am Tomas Surronn, Esq. Freperick H. Warp, Esq., M.R.C.S. T. Caarrens Wurtz, Esq., M.R.CS., FL, 8. Ne, eg I. Numerical Aperture Table. . The “Arerrure” of an optical instrument indicates its greater or less capacity for receiving rays from the object and ee transmitting them’ to the image, and the aperture. of a Microscope objective is therefore determined by. the ratio’ between its focal length and the diameter of the emergent pencil. at the plane of its emergence—that is, the utilized _ diameter of a single-lens objective or of the back lens of a compound objective. This ratio is expressed for all media and-in all cases by sin w, n being the refractive index of the medium and ~ the : Semi-angle of aperture. ‘The value of n sin u for any particular case is the ‘numerical aperture” of the objective, __*~Diameters of the Angle of Aperture (= 2 1): Theoretical | 5, Back Lenses of various oo Ilmi- Resolving ene-. Dry and Immersion | Numerical Watéer- | Homogeneous-| nating | Power, in _ | trating ‘Objectives of the same | Aperture. Dry cae Zevsneasion Power. | Lines to an Inch.| POWer- Power (3 in.) (w sin w= a.)'|: Objectives. } ob iectives,|° Objectives. |. (a4). |~ (A=0°5269 u (2) from 0-50 to 1-52 N. A. (m= 1) l(a = 1-33.)) (m= 1°52.) =line EK.) a Beta crear eal 1°52 180° 0’ 2:310 146,528 “658 1:50 161° 23" }2°250| 144,600 “667 1:48 | 158° 39° }2-190 |. 142,672 676 1:46 | 147° 49" |2+132) 140,744 “685 1°44 | 142° 40’ |} 2-074; 188,816 “694 1:42 138° 12’ |2*016| 136,888 “704 1:40 - | 134° 10’-/1-960! 134,960 “714 1°38 - 130° 26’ |1°904| 138,032 “725 1:36 126° 57’ |1‘850) 131,104° | +735 See 2 123° 40’ | 1-796! 129,176 - | _-746 : © 9’ 122° 6 1°770; 128.212 “752 130 tae me io 33) pee ats pe 1:30 155° 38"; 117° 34" |1-690). 125/390 | . «769 1:28 148° 98'| 114° 44" | 1-688. 123,392 “| -781 . [o} Ua) oO rit . § Pied ee POGUE Rete CRO Barer keer 1:22 133° 4"; 106° 45’ 1-488; 117'608 | +820 ; >] 1s fase. 8/1 40 en |4-aoat 18/758. | ee 1:16 121° 26’; 99° 29} 1-346) 111,824 “862 is Tee eee rd rp ae ihe ai ee r| “7 | 4-2: 7, 4 Be pon eS) Las meee 1-06 f wos art Se oe. 1 aba 102,184" | +943 1:04 102° 53’| 86° 21’ | 1-082! 100,256 “962, - 1:02 — i 100° 10"|- 84° 18’ |1:040| 98,328 |- -9g0 1-00 |} 180° 0 | 97° 317} 82°17’ 1-000! 96.400 | 1-000 0-98 .| 157° 2°} 94° 56’ 80°97"! ~960) 94,472 | 1-020 0:96 147° 99" | 929 24)" 78° 20" | +992). 92,544 |-1-042 0-94 +.140° 6’ | 89° 56’ 76° 24’ | -884| 90,616 | 1:064 092 | 138° §1’ | 87° 32'| 74° 30’) +846|. 88,688 | 1-087 0:90 128° 19’-|-85° 10’| 72° 36’ |- -810! 86,760 | 1-111 0°88 123° 17% 82° 51"|. "70° 44’ | 774." 84,832 | 1-136 0:86 118° 88’} s0° 34’| : 68° 54’ | +740; 82,904 | 1-168 0:84 114° 17’ | 78° 20"! 672° 6’ | --706! - 80,976 }'1-190'- 0-82 | 110° 10’| 76°. 8’) 65° 18’ | +672) 79,048 | 1+220 0:80 106% 16’.| 73° 58'|.. 63°31"; +640|. 77,120 | 1-250 0:78 102° 31’ | 71° 49"|~ 61° 45’ | -608| 75,192 | 1-282 0°76 98° 56’ | 69° 42'| , 60° ..0' | +578) 73,264 -| 1 B16 0°74 95° 98! | 67°36") 58° 16 | -548|} 71,336 | 1-351 0°72 92° 6’ | 65° 82'| 56° 32’ | -518{/ 69,408 | 1-389 0-70 88°51’ | 63° 31’) 549-50" | <490|*. 67,480. | 1-429 0:68 85° 41’ | 61°80’! 53° -9” |. -462 65,552 1°471 0°66 82° 36’) 59° 30’) 51° 28’. | -436} . 63,624 | 1°515 0:64 | 79° 85" | 57°.31’) 49°48" | -410/- 61,696 | 1:°562 0-62 76° 38'| 55° 34’). 48° 9’ |- +384! 59,768 | 1-613 0-60. | 73° 44" | 53°38} 46° 30° |. -360!. 57,840. | 1-667 0:58 70°. 54’ | 51° 42’| 44°51’ |. 836] - 55,912 |.1-724 0°56 68° “6! | 49° 48’|- 43° 14/ }<314| 58,984 | 1°786 0-54 65°22" | 47° 54’) 41° 37° | +292) 52,056. 11-852 0-52. “62°. 40" |46° 2} 40° (0% | +270! © 50,128 | 1-993. - 0°50 60°. 0’ | 44° 10’| 38° 24’ | -2501 48,200 -| 2-000 Exampite—The apertures of four objectives, two of which are dry, one water-immersion, and one; oil-immersion, would be compared on the angular aperture view as follows:—106° (air), 157° (air), 142° (water), 130° (oil). | Their actual apertures are, however, as 2 *80 “98 1°26 1°38 . or their numerical apertures. Scale showing || the relation of Millimetres, &c., to Inches, mn. _and em. ins, ESTES PRG Se SO ACEI ARE BST IS, SURE) PETES A DASE ESTA Pee SAE FEC eel BRE bt ee eR SR Ee 7 — ‘= ] a a a im : a | a a a tI mi | J rs a a @ m aS i a a | | 5 | | ml 000. =1 mm, 10 mm.=1 em, 19 om. =1 dm. 10. dm. =1 metre, II. Conversion of British and Metric Measures. = = = = ~~ : . (1) Lineau eta roh SLMS ie ch Cpa Aa manna Rs Micromillimetres, §c., into Inches, Go.) | * Znohes, &¢., into: we) ins, Bynes ele, Smee iene . hen ae Ceo ee 1 +000039| 1 089870} BL: yo 2007892) ine yy, 2 -900079.| 2 078741 | 52 2.047262 | 3 1-015991 3 000118} 3. 118111} 53: 2°0866383| =°5°° - 4.069980 _ 4 -000157| 4. "157482 | 54 24126008}; 22322 4-g93918 5 +000197| 5 196852]. 55° B165874 | PP? 9. Ba 9977 6 -000236| 6 9936083 BE. es o0aTaas |) COIER 5 o50707 7% QOOQTE! i: 7278503) D7 2DdNb | A 3.974979" 8 -000815 | 8" *314963 | 58 |) 2283485 | FPPO B.gogsag 9 000854; 9 --B54384/ BO 81802 | F9PO | gabon 10 000394} 10 lem.) +898704| 60 (6cm.) 2-862226) 799° 5.q7o954 11. -000433 11 -*488075 |; G1. 2°401896 | acon 6° 349943. 12) :000472| 12 6472445) 62. |.) 24409671 “su55 8 °466591 13 +000512 | 13: 511816} 68... 92480887} adoq 127699886 14 :000551| 14 “*551186} (64 27519708 | x55" 29°399772. 15. -000591/ 15 = 590556 | 65: “(2 550078 he Aga 16° -000630 | 16 +629997| 66. > 2598449 | oo 028222 17 000669 | 17 “16692971 6%. 2687819} soo, “081700. 18 °-000709:|' 18 #708668 6B... Br877180 [> too! USRR8S. -19 +000748| 19 ©. 748038 69°). 2716580) apo | OBB 3S 20 -000787 | 20 cm.) -787409| 70: (7 cm.) 2°755930 | sea del 221 0008271 BES 88770 I Meo! 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BOG 260) O19 1B. 2 3912-0 a : eee is 232°22 98 208 °4 tamond | 400 . 204-44 -96 » 2 204-8 a 350 - 176-67 94 FBO Be |S ROSPHORUS oes 300 148-89 92 197°6 || Bisulphide of carbon ie ae eee Bis 6 = Ao?) ee ee 210 ——-98-89: | 86 186-8. || Crewe Blane | 205. 96°11 | 84 - 183:2 || Rock salt ae 200 93°33 - 82 179°6 rhe ip: 195 90°56 | . 80 geo aes --190 87°78 78 - 479-4 || Linseed oil (sp. gr. 932) ane ee 185 89:0") 76 168-8 || Oil of turpentine (sp. Br 888) Uae 180 80-00 Loe en Es: 175 79°44 72 161°6 Sete a ied 76:67 70 158°0° || Sea water ep 1 73°89 68 154:4 || py i ek ihe 2) me zt 55 68*33 > 6 147°2 : a Baie ote <i 150 65+56 62 143°6 hee ts, B. 145 62°78 60 140°0 : ee: ae 140 60.0 | 58 136-4 ee EE ee ee a 135 57°22 56 132°8 : 5 Qe 1380 54-44. 54. 129-2 -Diamond -. ; Y 2 n 125 51 +67. | 52 125°6.||. Phosphorus + rite ae ERE ae ete || Bisulphide of ey, ie 110 43°33 | 46 114+g || Flint glass © ene 105 40°56 44. ‘111-2 || Crown glass & 100 37-78 42 107°6 |! Rock salt nares 95 35°0 40: 1040 Wot cn ae 3 90 32°22 38 100-4 Canada balsam : , 8 85 29 +44 36 96°8 “4 ae 80 96:67 | 3a 93°9 Linseed oil (sp. ‘gr. +932) Pg! 95 93°89 32 89:6 Oil of turpentine (sp. gre $86) ae 70 ae ~~ 80 86°0: || Alcohol” a 65 18°33 28 82°4 re p. 60 15°56 96 78:8 Sea: water es 55 12°78 24 75-2 || Pure water ecm 50 10:0 22 PG NS ate ae 45 7:22'|. 80 68:0 a Peas a 40 4:44 18 64°4 (3.) Ponarizing ANGLES Ss 35 1:67 16 60°8 fee 82 0:0 14 57°2 . 2 2 30 Seti 12 SSB Ley 3 25 = 3:89 10 50-0 .|| Phosphorus nh A aN y Pe . i Bisulphide of carbon ve 10 ws 1222 4 39:9 || Flint glass 5 — 15:0 2 35° 6 Crown glass 18) — 17°78 0 32°0 SG aE oe O08 BET or 28°4 Ae ae — 10 — 23°33 | — 4 24°8 |} Vanada ‘balsam = an = rae as . . : Linseed oil (sp .gr. +9382) — oe 25 GS 31°67 x 10 14-0 Oil of turpentine (sp. er. me — 380 — 34°44 | — 12 10°4 Alcohol — 35 — 37°22 | — 14 6°8 ' SAO NE SODA SAB a aes eee | — 45 — 42°78 AL Ss — 0°4 Pure water i x gee ees. —~50 . —45°56'| 4:20 - 4:0 || Air ERE ae ee OBJEC- TIVES. Foca Lenern Macniryinc Power. 2} 600 zo «| 800 Powell’s V. Table of Magnifying Powers. Beck's 2, Beck’s 1, | Powell’s 2, 1, and Ross’s'A. | Ross’s B, nearly.* Powell’s 3.| ‘Ross’s C, | Beck’s 3. | Powell’s 4, ‘ Ross’s D. 2 in. iim | EYE-PIECES. Beck’s 4, Focan LENGTH, . 2 in. 3 in. 3 in, Maeniryinc Power, Beck’s 5, Powell’s 5, Ross’s F, Ross's E. aay in, 50 623 835 125 1662 | 250 3124 3332 875 500 625 750 8335 1000 1250 1500 1750 2000 2250 2500 2750 8000 3250 3500 3750 4000 4250 4500 4750 5000 6250 7500 10000 12500 15000 2000€ 20 | 25 | 30 | 40 5 | 7 10 123 15 - AMPLIFICATION OF OBJECTIVES AND EYE-PIECES COMBINED. 10 15 20 25 30 40 12} 183 25 313 374 50 162 25 332 412 50 662 25 37} 50 62% 75 | © 100 332 50 662 832 100 13323 50 75 100 125 150 200 624 938 125 1563 1873 250 662 100 1332 | 1662} 200 2662 75 1123 150 1873 225 300 100 150 200 250 300 400 125 1873} 250 3123 375 500 150 225 300 375 450 600 1662 | 250 33381 | 4162 | 500 6662 200 |. 300 400 500 600. | 800 250 375 500 625 750 1000 300 450 600 750 900 1200 350 525 700 875 1050 | 1400 400 600 800 1000 1200 1600 450 675 900 1125 1350 1800 500 750 1600 1250 1500 | 2000 550 825 1100 1375 1650 | 2200 600 900 1200 1500 1800 } 2400 650 975 | 1300 1625 1950 } 2600 700° | 1050 1400 1750 | 2100 | 2800 750 1125 1500 1875 2250 | 3000 800 1200 1600 2000 | 2400 | 3200 $50 1275 1700. | 2125 | 2550 | 3400 900 1350. | 1800 | 2250 2700 | 3600 - 950 1425 1900: | 2875 | 2850 | 3800 1000 1500 | 2000} 2600 | 3000 | 4000 1250 1875 | 2500 | 3125 | 3750 | 5000 1500 | 2250 | 3000 | 38750 | 4500 6000 2000 | 3000 } 4000 5000. | 6000 } 8000 2500 | 3750 | 5000 | 6250 | 7500 | 10000 3000 } 4500 | 6000 } 7500 | 9000 | 12000 - 8000 | 10000 | 12000 } 16000 * Powell and Lealand’s No. 2=7 +4, and Beck’s No.2 and Ross’s B= 8 magnifying power, or respectively >, less and }; more than the figures given in this column, ‘HENRY CROUCH 1s : First-Class Microscopes. ! "Student's ‘Microscope. ‘New Family, and School : _ Microscope, — ; \ | New Series of Onjectives, Y New Accessories. NEW ILLUSTRATED ae ON RECEIPT OF ‘STAMP, LED ABROAD FREE, ; HENRY CROUCH, 66, farbleah London, 5 o. AGENTS IN AMERICA, JAMES W., QUEEN & 00., 924, es Street, Be v 8. JAN 20 1903 NEW YO RK BOTANICAL JOURNAL Ai Sesatnci OF THE ; ROYAL MICROSCOPICAL SOCIETY. AUGUST 1882. TRANSACTIONS OF THE SOCIETY. fe X.—On some Micro-organisms from Rainwater-Ice, and Hail. By R. L. Mappox, M.D., Hon. F.R.MS., &. (Read 10th May, 1882.) Tue study of the minute organisms belonging to the Schizophytes is one of special interest, for they touch the final history of all living beings, and very possibly hasten, if they do not actually cause, premature death. The researches within late years by very able microscopists and members of the medical profession have been numerous, though far from exhaustive. They embrace almost every field of inquiry, as the valuable Summary in the pages of the Journal of the Society so well attests; hence, some one may have preceded me in similar observations, as ice, hail, snow, rain, and dew have each been often examined; I am not aware, however, that the points I have to mention have been specially noticed; and I therefore trust they may not be wholly devoid of interest, even in their incompleteness. The winter of 1880-81 was of considerable severity from the ex- treme cold, which if already forgotten, allow me to recall to memory, by stating the fact that at my residence, one day whilst at dinner, with a good fire in the room, water when poured into a tumbler immediately became a mass of beautiful ice-crystals. The out-of- door temperature for several days was such, that the rain-water in the open garden rain-water butt was frozen to the depth of more than 12 inches. When the thaw occurred, I placed a large block of the ice, after well draining, in a clean new pan, and removed it into the house, set it in a fireless room, and covered it carefully from the dust.. Three days later I noticed a thin scum extending over the entire surface of the water in the butt, and at once put some on a slide and examined it with the Microscope. It was found to be a mass of micro-organisms lying in a pellicle inter- mixed with particles of soot, dust, and a few minute oily-looking Ser. 2.—Vor, II. 2H 450 Transactions of the Society. globules. The organisms differed from any I have ever noticed before or seen figured in any papers treating on Bacteria. Slides were prepared, some without staining the objects, others by staining with aniline blue, and much later on were photographed, using a +-inch objective and artificial lamp-light. The exposure upon the (commercially so called) “instantaneous” gelatino-bromide plates varied from four to five minutes. The negatives, from deficiency in actinic power of the light employed, were too thin to furnish fair paper prints; hence they were copied upon wet collodion into positives, and these by the same procedure into denser negatives with some enlargement compared with the originals. The micro-organisms in the pellicle, as seen under the Micro- Scope, appeared as minute rods or joints very irregularly shaped, and most of them larger at one end than the other, being either club-shaped or like the handle of a pistol, possibly due to the formation of a spore at that end, though this is doubted by some, for many had lying upon or near to the thick end a round or oval body, as if it had escaped from the adjacent rod. Some of the little bodies tapered gradually from the thick end. Where the placing of the pellicle on the thin cover-glass had not much disturbed its condition, the organisms were seen to lie very generally side by side, though not evenly, and in more or less slightly curved lines, as if the growth had been in a longitudinal direction upon a gentle curve, yet not giving rise to the sharper curve seen in many of the rods forming the mass. Amongst the numerous figures given in the ‘Annuaire de l’Observatoire de Montsouris,’ for the last three years, by M. Miquel, of the various micro-organisms he has found in the air by daily systematic observation, I have not noticed one similar to the one described. Besides these organisms there were a few small bodies in the pellicle, looking like ordinary bacteria and micrococci; but the general mass in the scum con- sisted of the large forms. ‘Their size varied considerably, the large ranging from the 75, to 45 of an inch, and the small of the same kind, to little more than half this length. Whether these bodies should be placed in the Schizophytes as Bacteria or Bacilli, I was doubtful, as more experienced observers than myself differed in opinion. No movement was seen in those freed from the broken edge of the pellicle. The difference in shape from the ordinary Bacilli rods might have been due to hindrance in their development from the previous severe cold, though if confirmed in future observations, it may be of a specific character. The block of ice removed to the pan, furnished on the third day a pellicle which was much thinner, but contained exactly similar rods. There was considerably less contamination. ‘The same was examined at different periods, and after remaining undisturbed for more than thirteen months showed the rods to differ but little from On Micro-organisms from Ice, &e. By Dr. Maddox. 451 the original ones ; being rather straighter, the club or pistol-handle shape still very evident, and the rods in somewhat more regular position. From the result of my rough cultivation experiments I am inclined to regard them as Bacilli. A few cultivations were attempted with the pellicle from the water-butt, also from the pan. For instance, I tried to cultivate them in sterilized (i.e. by boiling) normal urine, in sterilized infusion of Liebig extract of meat, upon cold boiled potatoes and the white of hard-boiled egg, without increased temperature beyond that of a fireless room, but with no positive success. Yet eight months later a speck taken from the pellicle, removed with some of the water from the butt at the time of the original observation, carefully kept covered and un- disturbed, and which contained the club-shaped rods in abundance, when placed on sterilized gelatine jelly prepared with infusion of Liebig extract of meat, showed ready growth in the rods, some to more than twice their original length, others multiplying into short joints. In the long ones the characteristic irregularity of outline was apparent in very many. The growth from two minute specks placed one at each end on a layer of the jelly, poured on a scrupu- lously clean slide, soon covered in length the intervening distance of an inch. Curiously, they were more or less arranged in circular groups, the centre being often occupied with a beautiful rosette of some salt crystal, though the individual rods were without regular arrangement, the short rods crossing each other in all directions. After such an interval it would be hazardous to say they were all derived from the club-shaped rods. What I wish to note is, that they grew into longer ones, so to establish their claim to be placed amongst the Bacilli. Later still, in the month of April this year, some of the same pellicle was sown on peptonized gelatine jelly without any evidence of the growth of the rods, and at the same date some placed on hard-boiled white of egg offered no change discernible, though in both cases there were very many minute organisms, as bacteria and micrococci, in Brownian move- ment. I may note that Mr. M. A. Veeder, U.S.A., found that various infusoria, conferve, &c., in the sediment of the clearest parts of blocks of ice from stagnant water of ponds and canals, would revive when melted, and considers such ice doubtful for drinking purposes. I will now pass to some remarks on the micro-organisms found in melted freshly-fallen hail. A rather heavy hailstorm happening on the 25th of last March, I took the opportunity to collect some of the hail for ex- amination while the storm continued, by dipping a perfectly clean tumbler into a drifted heap lodged in one corner of the window-ledge, without touching anything else ; immediately cover- ing the tumbler with a clean plate of glass, and msn be hail 2H 2 452 ‘Transactions of the Society. to melt in a room without a fire. On the second day a faint scum was visible on the surface in patches, enveloping grey, soot-like particles. Some of this pellicle seen under the Microscope showed very pale, motionless organisms lyimg in it, resembling rather elongated micrococci. ‘The water was left further undisturbed for another day, but furnished no appreciable difference except greater distinctness of the imbedded organisms. Some of the pellicle was stained with aniline blue, and mounted in acetate of potash solution without having been dried. Whether from want of refractive differentiation between the objects and mounting medium, or from the acetate of potash acting upon the pellicle, the outlines of the minute organisms were indistinct ; consequently a different method was adopted, which seemed to offer advantages. A speck of the pellicle was placed, with as little disturbance as possible, in a droplet of distilled water on the cover-glass, then, as recommended by different observers, dried over a flame, in this case very slowly. Afterwards it was covered with the following staiming fluid and protected from the dust : — Bismarck or aniline brown (of German make), 4 grains; citric acid, 16 grains; distilled water, 200 minims; boiled in a test-tube, cooled, filtered, reboiled, and a trace of carbolic acid added. After being covered with the staining medium for an hour it was washed with distilled water by tipping off the fluid, draining closely on blotting-paper, repeating this until the water was colourless, then drying again by gentle heat and mounting the cover dry. Deion I tried the aniline brown without the citric acid, but the addition of the latter appeared to facilitate the washing by increasing the solubility of the colouring agent without lessen- ing the staining qualities. Great care was required if the specimens were washed with the cover on the slide, for the least displacement caused the pellicle with its organisms to roll up into continuous lines. I am not prepared to say that the method of drying does not slightly shrink the objects. I fear it does, though I do not think more than osmic acid, as the substance enveloping the organisms appears indistinctly afterwards. The minute bodies found in the melted hail differed most completely from those of the frozen rain-water. In parts where but little disturbance of the pellicle occurred upon removal for examination, the organisms were seen lying very irregularly near to each other, whilst in what appeared to be a second pellicle formed just beneath the outer one, they occurred mostly in rows, and are often at rather an acute angle with one another. In size they differed, doubtless owing to being in various stages of growth and fission. On Micro-organisms from Ice, dc. By Dr. Maddox, 4538 The average size is from the szioo to the rstoo of an inch in length ; some looked round, others like elongated micrococci, and when fission was about to occur very like ordinary bacteria. As they were when free motionless, I felt inclined to suppose them to be micrococci, but from some cultivation experiments I believe they must be termed bacteria. Thus a speck of the pellicle was placed on freshly boiled white of egg, and kept carefully covered and turned down without touch- ing anything except by the broken shell edge. The second day, about thirty-six hours after the inoculation, on removing a minute portion and diluting it with distilled water, it presented an in- credible crowd of bacteria in rapid motion, resembling closely, if not actually, Bactertwm termo. On the sixth day the white of egg, at the spot of inoculation and for some distance beyond, pre- sented a beautiful pale canary-yellow colour, and on the eleventh day a bright deep rose-coloured spot also appeared, very closely to the seat of puncture, consisting of motionless micrococci. This has been successfully cultivated ‘through several generations on the same medium. A portion of the original pellicle placed on peptonized gela- tine jelly on the thin cover, and this placed over a tin cell cemented to an ordinary slide, ‘the surface of the tin circle being smeared with vaseline (as recommended, I believe, by an American microscopist), except at two small opposite points, and then kept at the temperature of about 58° F., had on the second day so softened the gelatine by the changes induced in it, that the spot of inoculation was quite fluid, teeming with minute organisms in most rapid motion ; hence, as several inoculations were made, and with like results, I conclude that chiefly bacteria and only few micrococci existed in the hail in a quiescent or resting stage, and when supplied with proper nutriment and more favourable condi- tions, the organisms, suited to the circumstances, quickly turned from the quiescent state to one of the greatest activity. Of course I do not pretend there may not have been different varieties in the hail, for the organisms of rain-water have been found to determine butyric, lactic, ammoniacal and putrefactive fermentation; but what appears to me probable is, that one if not more amongst the organisms supported the temperature, whatever that might have been, that determined the formation of hail, remaining in an almost quiescent state, for I believe the Bacteria have their resting stage, and that the more advantageous conditions of nutriment and temperature speedily determined activity. The general mass of the jelly remained free from visible change. Before actual fluidity of the material occurred, close to the inoculated spot, numerous small, round, grey, finely granular, ascococcus-looking 454 Transactions of the Society. patches made their appearance, and gradually coalescing, joined the edge of the inoculation. Of their nature I can say nothing definite. How they came there is rather puzzling, seeing none formed in other parts of the jelly. At the same time, and in a similar manner, the same nutrient medium was inoculated with a speck of the old pellicle from the ice in the pan: the club-shaped rods did not, at this date and in this medium, undergo any visible change ; but some of the minute organisms showed development, though not to any great degree, only exhibiting Brownian movement, whilst some of the same pellicle placed on the boiled white of egg at the same time as the former experiment with the pellicle from the hail, furnished on the second day minute organisms which, when seen in a droplet of distilled water, were not very active; but the club-shaped rods, if they multi- plied, did so to an indiscernible extent. ‘There was no chromo- genous change at the point of inoculation, as with the pellicle from hail. The minute organisms found in the melted hail-water scum, were no doubt derived from the rain-drops congealing round the air-borne dust-particles to which they were adherent, and after- wards slowly multiplied afresh on the surface of the melted hail. Some have doubted whether bacteria form part of the atmospheric dust; but the very careful experiments and cultures of M. Miquel, at the Montsouris Observatory, tend to prove that such bodies are suspended in the air and to be constantly found in rain, hail, and snow. Numerous figures are given. ‘To avoid contamination in culture experiments, when objects are only for a short time exposed to unfiltered air, is a great source of difficulty. M. Miquel remarks in the ‘ Annuaire,’ published this year, that snow, usually regarded as the great air-purifier, is not so in reality, for although it largely attracts the bacteria it meets with in its passage, it does not fix them like moistened earth; as a sudden squall cutting into the snow will often again bear them aloft. January and February have furnished him with the minima; October and November with the maxima in the gatherings. Cold he places the first, and extreme dryness the second agency in the destruction of atmo- spheric bacteria. Rainfall much lessens their number, whilst this again rises upon the succeeding dryness. He finds them ten times more numerous in the centre of Paris than in the country, for the same volume of air, and he gives the proportional numbers as, micrococci 93, bacilli 5, bacteria 2, for the first, and micrococci 79, bacilli 14, bacteria 7, for the second. He also furnishes the mean for the different months. The micrococci are pretty con- stant, the bacilli highest in April, May, July, and August, and lowest in November, January, and June; the bacteria nil in January, February, and June, and highest in the month of May. On Micro-organisms from Ice, dc. By Dr. Maddox. 455 The difficulty is to find a suitable medium for nourishing or rejuvenating all the aerial germs that have been gathered by the aspirator. The great extremes of heat and cold to which the spores of many of the Schizophytes have been exposed without loss of vitality is a point of much interest. The Rey. Mr. Dallinger, in his careful experiments, found the death-points in dry heat, for the mature monads that he had studied, to range from 138° F. to 142° F., but their spores supported for five to ten minutes 250° to 300° F.; whilst the same heated in fluid were destroyed at 212° to 268° F. M. Van Tieghem found some micrococci and bacilli to flourish at 74° C. M. Miquel cultivated one form from the Seine at 70° C., which died when the temperature was raised to 72° C. Professor Frisch finds that the bacteria seen in diphtheritic exudation and in puerperal fever resist a minus temperature of 87°5° C. without destruction, and the bacilli spores to resist extremes of cold better than the rods. M. Miquel states that a particular Bacteriwm found in snow resisted a temperature of 26° to 30° C. below freezing for three hours, and for more than twenty days a mean temperature below zero of 2°5° C. The enumera- tion of such experiments might be greatly multiplied. Drs. Cohn and Mendelsohn state that it required a powerful galvanic battery current of five elements to destroy the vitality of the bacteria they experimented upon. Not to quote more largely, it seems quite incomprehensible that such minute organisms should be able to resist such extremes of temperature, and that the so-called mucous, gelatinous, albu- minoid, cellulose, or by whatever name it may pass, covering, which is permeable to fluids, should be able to defend the living contents against such extraordinary variations of heat and cold. Here, under the hand of most careful experimenters, the reasonable- ness of previous doubt must give place and credence to the senses. Can it be that the envelope that surrounds the organism normally, when subjected to dry heat, dries so entirely and rapidly as to prevent the entire loss of moisture from within, or that the encap- sulation, so to speak, is so perfect, that there is no room for the generation of high-pressure steam, and that under moist heat the coagulation is so effective that it shrinks the outer material so closely upon the contents, that steam cannot be generated except under rupture? Or can the rapid chemical changes they can effect, suffice to continue their vitality under such abnormal conditions ? We may largely theorize, though I fear only to record our ignorance, when we attempt to limit the manifestations of life by predeterminate lines, derived from the study of higher organisms, though amongst these there are some, as the Aphides, stated to 456 Transactions of the Society. resist extreme cold, and in the case of seeds and chestnuts they are said to have survived the exposure to the very low temperature of —100° C., and very lately in experiments by Messrs. de Candolle and Pictet the refrigeration was carried to — 80° C., the seeds germinating afterwards. I think experiments have also been made on hybernating animals, but I do not remember the exact temperature destructive of life. The minuteness, however, of the Bacteria almost forbids comparison with the other objects. Such details I fear must be sadly wearying to those who take no special interest in the study of these micro-organisms, and to such I offer every apology. Nevertheless, I would ask them to try and estimate carefully the value of the study of these ubiquitous objects. ‘They set up minute changes in some of the articles of our dietary as either invite or repel the organs of smell and taste. The numerous varieties found by M. Duclaux in the imperfect making of Cantal cheese, at once point to a large field of inquiry among the articles that are in our daily diet. They play a vast role as the grand scavengers in the silent destruction of lifeless forms and are thus beneficent agents; they are the companions of our life and accompany, if they do not originate, many depressing and fatal diseases, multiplying so rapidly in cases of lowered vitality of their host that they kill by their numbers, or perhaps by depriving the nutrient fiuid of part of its oxygen, though this, as pointed out by Mr. Dowdeswell in his excellent article upon Septiczemia,* seems, in the smaller forms at least, improbable. ‘The chemical changes induced by their own require- ments may furnish noxious matters detrimental to the life of the higher organism—and harmless forms under new conditions may perhaps acquire such virulent properties, that in the state of spores the minutest quantity suffices when inoculated into the connective tissue of a healthy animal, if such have not acquired previous immunity, to cause severe illness if not certain death. Their importance, as affecting, on a vast scale, the life of man and of animals, invests them at least with the symbol of respect. It is only by cultivation that we can hope to distinguish the living from the lifeless, for may we not have before us in such as are gathered from the air, some that are dead, and some of what Dr. Phipson calls “ fossil forms.” Morphologically their resem- blances may be so great that their differences are to our powers other- wise indistinguishable. Possibly some may be inert when cultivated in one fluid, and highly poisonous in another—as in living bodies. * Quart. Journ. Micr. Sci., xxii. (1882) p + M. Miquel found by the statistics of ine ae that occurred last year at Paris, that there were nine rises which closely corresponded each to a rise in the number of Schizophytes found in the air. He merely points out the interesting coincidence. On Micro-organisms from Ice, &e. By Dr. Maddox. 457 The necessity for a certain amount of the poisonous material to be introduced or acquired in the system to produce on the one hand immunity, or on the other hand fatal effects,—the alteration some undergo by exposure to air,—the re-acquirement of highly virulent properties after having had them lessened by culture, may, perhaps, point to the very variable results exhibited in contagious maladies, and malarial fevers, under similar exposures; some receiving the contagium, so to speak, at its first offer, others resisting for lengthened periods. In the case of malarial fevers there are some points that furnish material for future study. I will mention an instructive case that came under my notice many years since. In the neighbourhood of Constantinople, and especially at the Dardanelles, malaria was endemic. Asswming malarial fever to be consequent upon the introduction into the system of the Bacillus malarix of Klebs and Tomassi-Crudelli, this point for inquiry arose. A sailor had had at one of the ports in the East Indies a first and severe attack of intermittent fever, from which he speedily recovered, and remained free from any recurrence for thirteen years, although visiting various localities where such fevers were common ; yet the same night that his vessel anchored, during the day, in the Golden Horn, he was seized with a severe attack of malarial fever, which necessitated his entry into the hospital. None of the officers or crew suffered similarly, though remaining many days at anchor. Are we to suppose the germs of the former malady remained quiescent in the system for the period of thirteen years, and that a few hours in a suitable locality sufficed to set them into activity and develope a return of the ague; or was he an individual very susceptible to malaria? I scarcely think so, as he was free at other ports where the malady was common. Again, should the second attack be supposed as unrelated to the first, under the assumption that he in some way imbibed the malaria in passing the Dardanelles, and that the incubation took three or four days to develop itself, or was it that out of all the places he had visited in the course of his voyages for thirteen years, this locality was the only one to furnish the necessary conditions for a return of the original malady, he being previously in good health ? In the malignant form, in the neighbourhood of the Darda- nelles, I have known individuals die in the cold stage within sixteen hours. Had such imbibed a really toxic quantity of the malarial poison—I am expressly assuming the correctness of the Bacillus malariz theory, which Dr. Sternberg, U.S.A., finds reason to doubt —and did the organisms multiply in such a short period throughout the system or in some vital organ as to thus speedily terminate life without any reaction, under every effort that time permitted ? Mr. E. L. Moss, Staff-Surgeon R.N., found, after forty-eight 458 Transactions of the Society. hours, by ingeniously contrived experiments, organisms in the blood drawn from intermittent fever patients which he could not find in the fresh blood. It is questionable whether they were the same as the Bacillus malariz. Dr. Marchiafava contends for the correctness of the statements of Klebs and Tomassi-Crudelli, for he finds the blood of all parts of the body, in those stricken with malarial fever, to contain in the initiative or cold stage both barren and spore-bearing rods, and in the hot or fever stage, only free spores. The cyclical course of various infectious diseases is attributed by Dr. Wernich and Professor Salkowski, from their careful experi- ments, to the destruction of the micro-organisms in the living body by their own products, i.e. they are destroyed by their own excreta. What the term of life may be for the spores of these lowly forms awaits inquiry. The germs of Bacillus anthracis are said by M. Pasteur to have survived a period of twelve years, but how much longer, lies in the investigations of the future. The medical digression has been purposely made to try and engage some of the waste microscopical energy of the members of this Society by showing that complex phenomena attributed to the action of such micro-organisms yet wait for intelligible and satisfactory answers. There is one hint I would throw out_to those who need the stimulus of patient work, viz. to follow up the researches of M. Chappuis, by watching the effect of ozone upon the life of the Schizophytes. Such an inquiry may lend light to the obscurity that now veils some of the depressing catarrhal epidemics, such as influenza, &c. Although much has already been accomplished, much has to be repeated. As yet we only touch the edge of this vast field for research. In it stands a complex problem for those to solve who have the time and patience to compete for even a fractional part. Fortunately encouragement comes from the important ex- periments now made in other countries, in the form of “ pre- ventive inoculation,” from which, already, highly beneficial results have been achieved, conservative both to life and to the pocket. May we not apply to ourselves what has been so ably said by Dr. Burdon Sanderson in his recent Lectures upon Inflammation ? “ We are all of us, old and young, too apt to forget how slow and gradual is the process by which we come to a right understanding of objective facts. Let us be prepared to give equal credit to the past and the present, accepting what is new without losing sight of, much less rejecting, what is old.” [Since the foregoing was written, that indefatigable observer Dr. Koch has discovered another of the Bacteria which he, followed by Dr. Baumgarten, considers as the cause of tuberculosis—a disease On Micro-organisms from Ice, de. By Dr. Maddox. 459 which is responsible for about one-seventh, if not more, of the deaths of our population. Dare we hope that further ex- perimental research may ultimately arrive at some method of diminishing this frightful annual loss? Shall we get a clearer insight into what we term the law of heredity? Supposing infection ab utero, has it no limiting period of incubation? must all ages bend to its presence? J am not aware whether the organisms found in fowl cholera have as yet been discovered in the newly laid egg. The answer can only come from careful experimental inquiry. In it lies the hope of discovering the means of immunity, and I trust that, in spite of hasty and prejudiced legislation, such researches may yet be made in this country, as will conduce, not alone in this, but in other maladies, to the future welfare of both man and beast, so that we may say in the words of the poet :— “?Tis worth a wise man’s best of life, *Tis worth a thousand years of strife, If thou canst lessen, but by one, The countless ills beneath the sun.”’] 460 Transactions of the Society. XI.—The Relation of Aperture and Power in the Microscope (continued).* By Professor Apps, Hon. F'.R.MLS. (Read 14th June, 1882.) II.—The Rational Balance of Aperture and Power. The discussion of Part IJ. relates to one and the same matter, viz. that from all points of view which come under consideration in the use of the Microscope, a certain proportion of aperture to power is the necessary basis of perfect performance. The question we have now to consider is: whether it is possible to arrive at a more definite determination of that propor- tion than is furnished by the preceding somewhat general dis- cussion of the question of wide and narrow apertures, and in particular, whether that can be done in such a way as to establish a rational standard for the practical construction of the Microscope. So far as I know, this matter has not yet been the subject of any kind of regular discussion, though it will be admitted, I presume, by every microscopist to be one of great practical importance. I have now directed my attention to it for more than ten years, not purely from theoretical points of view only, but by means of a long series of practical trials in which I had the advantage of the co-operation of Dr. C. Zeiss, of Jena, and I propose therefore to point out here the principles which, in my opinion, furnish an approximate standard for determining the proper balance of aperture and power in the Microscope. For this, two distinct questions must be treated separately. First, the relation of aperture to power must be considered in regard to the entire Microscope and we must ascertain what amplification of the ultimate image of the Microscope is useful, or necessary, for every given aperture, and conversely, what aper- ture is required for the proper utilization of a given amplification. If the subject admits of a scientific discussion at all, it must be possible to indicate the proper relation of aperture and amplifica- tion without having regard to the particular manner in which a given amplification is obtained by the co-operation of objective and eye-piece, provided, of course, that the amplification is obtained with the best possible quality of the image. The second question is, what division of the entire power of the Microscope between the objective and ocular will fulfil the condition of a perfect image under a given amplification. This relates essentially to the practical aim of the discussion—the determination of the focal length of the objective which is required for the utilization of a given aperture. * The paper (received 11th April) is written by Professor Abbe in English. The Relation of Aperture and Power. By Prof. Abbe. 461 i. Relation of Aperture to Power in regard to the entire Microscope. . 1. The first question may be dealt with under these two heads :—(a) What are the smallest dimensions of microscopical detail which are within the reach of any given aperture ? (b) What visual angle is required for the distinct recognition of details of given dimensions? If these can be answered in a reliable manner, the first question will have been disposed of. The smallest dimensions which are within the reach of a given aperture are indicated with sufficient accuracy by taking the limit of the resolving or separating power of that aperture for periodic or regular structures, i.e. the minimum distance apart at which given elements can be delineated separately with the aperture in question. The numerical expression of that minimum distance is A i eresh ee where a denotes the numerical aperture and X the wave-length of light ; a fair average is obtained for the latter element (with observations with the eye and white light), by taking X = 0°55 w = 0°00055 mm.; i.e. the wave-length of green rays between the lines D and H, very near to the point of maximum visual intensity in the diffraction spectrum. Though this expression applies in strictness only to the visi- bility of periodic structures composed of regularly arranged elements, it may be taken as an approximate measure of delinea- ting power in general, i.e. in regard to structures of every composition. My theoretical investigations and experiments show that with objects of every shape and arrangement, the micro- scopical image will not present any indications of structure, the dimensions of which are perceptibly below the value of 6, given (for any aperture) by the above formula. Prominences of any shape on the outline of a coarser object, for example, will disappear more and more as their dimensions approach the value of 6 for the aperture in use. Isolated elements of triangular, or quadratic, or rectangular figure will look more and more alike (becoming more and more circular or elliptical in form), as they diminish in size to the value of 6.* The loss of diffracted light attendant upon the limitation of the pencils by the lens-opening, changes or obliterates those details which are beyond the limit of the resolving power. Consequently the microscopical image of an object of any composition whatever, will always be disstmdlar to the object to the same extent; and the limit of resolving power therefore indicates the limit of simalar or correct delineation generally. * I have verified these theoretical inferences, for small apertures, by many experiments, with objects of very different nature. 462 Transactions of the Society. Hence every aperture is fully utilized when the amplification of the entire Microscope is sufficient for a distinct and convenient observation of details corresponding to the value of 6. Lower amplifications would not exhaust the aperture, because indications of real structure which exist in the image, would remain hidden from the eye. Higher amplifications, on the other hand, will not promote the recognition of the objects, because all the indications of minuter scale which they might perhaps display, do not exist in the objects, but belong to the image only—they are simply modifications of the image due to the aperture in use. Such higher powers would therefore afford nothing more than an exaggeration of those features of the image which are not conformable to the real nature of the object. We have now therefore reduced the problem under consider- ation to the single question: What amplification is necessary and sufficient in order to display the 6 of every aperture, under that visual angle which is required for distinct vision ? The facts of observation which are within the reach of every microscopist, afford all necessary data for an approximate determi- nation of this amplification. The striation of an ordinary specimen of Pl. angulatum becomes visible to a very sharp-sighted eye under an amplification of 150 diameters. As the closeness of the lines is about 0°5 w (50,000 to the inch) they are thus recognized under a visual angle not much exceeding 1’ of are. But dastenct and convenient observation for an average eye will in any case require a much higher power; how much higher, will of course vary with different individuals. I am, however, sure to leave sufficient latitude for personal diversities in assigning 300 and 600 diameters as the limits of useful amplification for details of these dimensions. In observing the diatom, no one, I presume, will deny the advantage of increasing the power if it 1s below 300; and on the other hand, no one will admit any further advantage in going beyond 600, provided the observation is made with an aperture not exceeding 0:6, which shows the striz, but nothing more.* It may be inferred from this example, in accordance with many similar facts, that satisfactory observation requires that the smallest detail of the microscopical image shall be displayed under a visual angle of not less than 2' and not more than 4’, approxi- mately ; angles which correspond very nearly to the amplifications 300 and 600 for dimensions of 0°95 p. This admitted, we obtain at once the number of diameters which are required for properly utilizing any given aperture. If a dimension 6 is to be displayed under a visual angle of v minutes of * Much higher powers may of course be utilized in the observation of Pl. angulatum with objectives of wide aperture. In this case, however, the image contains indications of form upon the markings of much minuter dimensions. The Relation of Aperture and Power. By Prof. Abbe. 463 arc, the necessary amplification, N, for a distance of 250 mm. or 10 inches (1' being = 1 : 8438) is 250 v ~ 3438 | 5” and substituting for 6 its equivalent in terms of the aperture (=) a we obtain the general formula :— 250 2av ae oe or, if X is taken = 0°00055, N = 264:'5 av, By introducing into this formula v = 2' and v = 4 respectively we obtain the figures of useful amplification for a series of different apertures. as shown in Table I.—useful, that is, so far as delineating power is concerned, putting aside for the moment any question as to the dlumination of the object, which, as explained hereafter, allows of somewhat greater apertures. TABLE I. 5, N, Amplification for obtaining a Aperture, Aperture-Angle Measure of the Visual Angle of (air). least attainable Detail. ey v=! = Ie 0°05 a°7 5°50 26 53 0°10 11°5 2°75 53 106 0°15 17°2 1°83 79 159 0°20 23°0 1:37 106 212 0°25 29° 0 1:10 132 265 0°30 35°0 0:92 159 317 0°35 41°1 0°79 185 370 0°40 47°2 0°69 212 423 0°45 03'°5 0:61 238 476 0°50 60:0 0°55 264 529 0°55 66°7 0°50 291 082 0°60 (oe 0°46 317 635 0°65 81°1 0:42 344 688 0°70 88°8 0°39 370 TAX 0°75 97°3 0:37 397 794 0°80 106°3 0°34 423 846 0°85 116°4 0°32 450 899 0:90 128°3 0°31 476 952 S95) 143°6 0:29 5038 1005 1:00 180°0 0°27 529 1058 1:05 of 0:26 555 1111 1:10 0:25 582 1164 1°15 0°24 608 1217 1:20 0°23 635 1270 1°25 0°22 661 1323 1°30 0:21 688 1375 1°35 0:20 714 1428 1-40 0.19 (Ea) 1481 1:45 0°18 767 1534 1:50 0°18 793 1587 464 Transactions of the Socvety. Conversely we can obtain the aperture a, which is sufficient for the utilization of a given power of N diameters, provided a visual angle v' is required for the least detail within the reach of that aperture. This is given by the formula ) 4, ap Sees 264°5 * Table II. shows the values of a corresponding to different amplifications under the supposition of a visual angle vy = 2'; it exhibits, therefore, the maavmum aperture which can be admitted as useful for any given power under the above assumptions. The assumption of any other visual angle as necessary for distinct vision of the least detail, would change a in the inverse pro- portion of v, so that for v = 1' we should have twice the figures of a given in the second column of the table, and for v = 4’ one-half. Tas_eE II. a, N, Aperture for Amplification | @ Visual Angle of Aperture-Angle for 250 mm. the least detail, (air). De fe) 10 0:019 2°2 20 0-038 4-4 30 0°057 6°5 40 0-076 8:7 50 0-095 10:9 75 0:°142 16°3 100 0-189 21°8 150 0-284 33°0 200 0°378 44°4 250 0-473 56°95 300 0°567 Goat 350 0° 662 82-9 400 0°756 98°2 450 0°851 116°7 900 0-945 141°8 600 1:134 700 1°323 800 1°512 900 1:701 1000 1°890 i Though these figures cannot of course pretend to be more than an approximation to the actual requirements under various given conditions, yet they will indicate with sufficient accuracy the limits of useful power; in that the delineating power of any given aperture cannot be fully utilized when the number of diameters (obtained with a really good quality of the image) is much below the minimum figures of the table; and that, on the other The Relation of Aperture and Power. By Prof. Abbe. 465 hand, we shall have an empty amplification, which does not improve the representation of the objects, if the power should go much beyond the maximum figure. The salient fact suggested by the two tables is the relatively low figures of amplification which are sufficient for very wide—in particular for the widest—apertures; and, conversely, the small apertures which are sufficient for the low powers of the Microscope. I do not, of course, intend to assert that, under particular cir- cumstances and for particular purposes, much higher figures of amplification than are shown in the tables may not be very useful or even necessary ; as, for instance, for counting, measuring, draw- ing, &e. What I wish to convey is, that in the present state of the Microscope they are not required and are not even advantageous, for research, i.e. for the proper recognition of the objects. A visual angle, for the minutest elements of a microscopical image, of 2', or at all events of 4’ (which is about the eighth part of the moon’s apparent diameter), is certainly quite sufficient for distinct observation. If indications of shape or arrangement should be found in the image, which are too minute for the powers given above, they must be at any rate of minuter dimensions than the values of 6 assigned by the first table. Indications of that kind— if such there be—have no true relation to the objects, but are attributes of the image only—mere optical phenomena, dependent upon the limitation of the delineating pencils by the lens-opening. Apart from all theory and experimental demonstration in sup- port of the principles in question, the practical experience of micro- scopists has sufficiently established that there 23 a limit to the performance of the Microscope, and one depending on the aperture of the objectives in the manner pointed out above. No kind of microscopical object can possibly afford in any respect more favourable conditions for the recognition of minutest details than those very expressive (and at the same time very simple and regular) structures of the silica skeleton of diatoms. But even with this kind of object not one trustworthy observation is on record in favour of the assumption that any given aperture, be it either 0°3 or 1-40, could reach a finer detail than is assigned by the table above, whilst there are many indubitable proofs that these theoretical limits may be as closely reached as can be expected, having regard to the difficulty of a strict determination of the actual circumstances of observation. The low figures of amplification suggested above, even for the widest attainable apertures—low in face of the views of many microscopists—are an unavoidable inference from the principle under consideration. In support of this inference I may, however, appeal to the evidence of many experienced naturalists who have done valuable work in lines of research dealing with the most Ser. 2.—Vot. II. dae | 466 Transactions of the Society. minute and delicate objects, and who agree that all real increase of our knowledge, even in these branches, has been originally obtained, or at least could have been as well obtained, by powers not much exceeding 1000-1200, whatever kind of lenses may be in question. 2. I cannot, however, restrict myself to the suggestion that excess of power, in proportion to the aperture in use, is simply of no advantage for the recognition of microscopical objects, but I must go further still, and express the opinion that excessive power is, or at least may be, a positive obstacle to correct recognition, because it will unavoidably lead the observer to take mere optical pheno- mena of the images for real attributes of the objects. ‘The following considerations will justify this view. If we observe a frustule of Pl. angulatum with the small aper- ture of about 0-6, in which case one set of lines only is exhibited at once, we may obtain a well-defined image of these lines under a power of 1000 diameters, or even more, provided a relatively short focal length of the objective and a moderate eye-piece are applied, and the illumination is effected by a very narrow beam of intense light. This power apparently displays much more than a lower power of 350 or 400 diameters with the same aperture. We see the striz as broad ridges or grooves widely separated from one another, and we recognize a distinct proportion between the breadth of these apparent ridges and their interspaces, which is 1 : 1 very approxi- mately ; whilst with 300 diameters we only catch just the fact of a striation, and nothing more. In this case now, we know that all details which are given by the 1000 diameters are mere optical illusions, because we are able to control and correct the indica- tions furnished by that power with the low aperture, by the image presented by an equal power, but having an aperture of 1:2. But if it had happened that a system of wider aperture than 0°6 had not hitherto been made, microscopists would cer- tainly have believed in the existence of ridges and grooves of equal breadth on the scale of Pl. angulatum. In this example it is unquestionable that the image obtained with an aperture of 0°6 under 300 diameters is less far from the truth than the image with the same aperture under 1000 diameters. The indeterminate striation is an indication of real structure, inasmuch as there are equidistant rows of elements in the diatom, which must appear as strie as long as the elements themselves remain occult; the exhibition of these rows as determinate ridges and interspaces with a distinct relation of breadth is a positive adulteration of the image of the structure. What holds good for an aperture of 0°6 must also hold good for every larger aperture relatively. I have before me Dr. Wood- ward’s magnificent photographs of Amphiplewra pellucida, Pl. angu- The Relation of Aperture and Power. By Prof. Abbe. 467 latwm, and other diatoms, taken with the best wide-angled lenses under amplifications of about 3000 and more diameters. Now the Amphipleura of these photographs, taken with apertures of 1:2-1°3, is the true equivalent of the Pl. angulatum of 1000 diameters with only 0°6 aperture. It shows the same determinate and energetic striation with equally broad ribs and interspaces, which are always seen when the closeness of the structural elements is not far from the limit of separation for the aperture in use. Theory and experiment show that these details of the image have no relation to the real composition of the object, that they exhibit nothing more than fypical pictures of rows of elements of any shape and magnitude whatever, when their closeness approaches the value of 65 corresponding to the aper- ture. It would be contrary to all analogy to expect that in Amphipleura alone we should have real bands or ridges, and not, as in other diatoms, distinct elements of double periodic arrangement with different closeness in different directions. This admitted, the enhanced expressiveness and determinateness of the image with the higher power is just the opposite of enhanced recognition, because the eye is caught by features which are entirely foreign to the object. If I wanted to show to any one what the Microscope has really revealed of the structure of diatoms, I should request him to inspect the said photographs at a distance of three or four feet, in order to restore the smaller visual angle corresponding to an amplification of about 1000 diameters. What he is able to recognize under these circumstances are the vestiges of true structure—indefinite, perhaps, but not falsified ; what he sees move under greater visual angle is nothing but the display of dissimilarity of object and image arising from the lack of aperture. The 3000 or 4000 diameters could improve the recognition of the real structure, only if they were obtained by apertures of 3°0 or 4°0.* It is by no means otherwise with the very minute objects of entirely different lines of research. If the image of a bacterium or a very delicate flagellum is exhibited under a power of 3000 diameters with more distinctness, as regards shape and magnitude, than is possible with one of 1000, the surplus will always be a surplus of mere optical dissimilarity. The effects of excess of power in the Microscope may be illus- trated by similar facts of astronomical experience. Astronomers * The figures of the tables should not, however, be applied directly to photographic performance, but the powers indicated for each aperture should be increased in the proportion of 0°41: 0°55 (3: 4 approximately), and the aperture corresponding to a given power diminished in the same proportion. Owing to the shorter wave-length of the rays of maximum chemical intensity, the value of 6 for every aperture is proportionately smaller in photographic than in ocular observation. 212 468 Transactions of the Society. know very well that the most trustworthy power of a telescope is not the highest power which the instrument will bear, but that power which has a certain relation to the diameter of the objective. If they use a higher amplification than about 40 per inch of the diameter of the objective (i.e. 120 for a 3-inch, 400 for a 10-inch objective) they begin to detect diameters of stars which have no diameters. A very good 38-inch objective will, indeed, show more under a power of 300 than of 100, apparently ; just the same as with a very good wide-angled Microscope-lens in regard to 3000 and 1000 diameters. In fact, the 300 diameters of the 3-inch will reveal, with somewhat bright fixed stars, very neat and distinct disks which are invisible, or nearly invisible, under a power of 100. But these disks disappear at once, when the amplification of 300 is obtained with an objective of 9 inches diameter.* Astronomers are accustomed to apply much higher powers than 40 per inch for various purposes; but they do not apply them whenever they want to recognize the true shape and magnitude of their objects. It is just the same in the Microscope. The greatest possible approximation of the image toa true projection of the object is not obtained by the highest powers, but by those powers which are just capable of exhibiting to the eye the least dimensions of real structure within the reach of any given aperture. I invite the particular attention of microscopists to this subject, as it is in my opinion of great practical importance in regard to the proper use of the Microscope. For my present purpose I may confine myself to the statement that it does not belong to the rational aim of microscopical optics to enhance the amplification of the Microscope beyond those moderate figures which are sufficient for utilizing the attainable apertures; the rational aim is rather to obtain the best possible accomplishment and the most favourable conditions, for the use of these moderate amplifications. 3. So much as to the proper relation of aperture and amplifica- tion at the upper end of the scale of microscopical performance, where the question is of the largest attainable apertures and highest useful powers. In regard to the lower end of the scale, the suggestions indicated by Tables I. and II. will require some further remarks. So far as the principle is admitted on which the computation of the tables has been based, we must consider the small apertures assigned for the lower powers of the Microscope as sufficient, * The physical conditions of the phenomena in question are not the same in the telescope and in the Microscope, but yet very similar. In both cases the effects do not arise from deep oculars—as is often assumed—but depend only on the relation of the total amplification of the instrument to the aperture. The Relation of Aperture and Power. By Prof. Abbe. 469 provided a visual angle of not less than 2’ is required for the smallest detail within the reach of every aperture. An increase would be a matter of necessity only if a given observer should consider a smaller visual angle, say 1', as sufficient for distinct observation. On the other hand, it is certain that a surplus of aperture is no drawback by itself, but only in regard to certain practical points, which have been spoken of in the first part of this paper. Among these are some which argue in favour of small apertures (penetration, working-distance, insensibility of the cor- rections, &c.), and one which is in favour of increased aperture (brightness of the image). The proper function of the theoretical considerations of the foregoing paragraphs cannot therefore be to establish an absolute rule, but rather to afford a proper basis for finding a rational balance between the various requirements of the practical use of the Microscope. Regarding those in which the advantage is always on the side of the lower aperture, it will be obvious that all of them become less and less important as lower apertures and lower powers are in question. As has been pointed out in the first part, restrictions of the working distance and inconvenient sensibility of the systems (unsteadiness of the corrections for different thicknesses of the covering glass, &c.) are not met with as long as the aperture does not exceed 0°25 (about 30°) and even with somewhat greater apertures, up to 0°5, they do not occur in any very obnoxious degree. The third element, the penetration of the Microscope, has been more fully discussed on another occasion,* where it was shown that with decreasing amplification the actual penetration, i.e. the depth which is accessible to the eye with one focussing, is more and more the result of the accommodative faculty of the eye and more and more independent therefore of the aperture. With very low powers, not much exceeding 50 diameters, a normal eye has a perceptible amount of depth of vision without any regard to the aperture. The lower the power, therefore, the more liberty is left for increasing the aperture in proportion to the power without: any perceptible disadvantage in respect to the various points above mentioned. There is, as I have said, one element in the performance of the Microscope in which a surplus of aperture will be a benefit, viz. the illuminating power, or the brightness of the image. It would, however, be a great mistake to expect that this should be without any limits or conditions, as the following considerations will show :— So far as the illumination of the objects by transmitted light is effected with light of a given intensity, and the illuminating pencils utilize the whole aperture of the objective, the brightness * See this Journal, i. (1881) p. 689. 470 Transactions of the Society. of the microscopical image depends solely on the diameter of the pencils at their emergence from the ocular, and is in the direct proportion to the square of that diameter. This diameter (d) is strictly expressed by the simple formula d=20-5 (ord = 275); if N denotes the amplification of the ultimate image for a distance of vision = J, and a the numerical aperture of the system. If we have a narrower illuminating pencil, which does not fill the whole opening of the system, the numerical aperture corresponding to the angle of the illuminating pencil must be substituted for a, instead of the full numerical aperture of the system. The diameter of the emergent pencils, and consequently the illuminating power, is entirely independent of the particular composition of the Microscope (objective, ocular, and length of the tube), and is solely determined by the aperture and the total amplification (the accidental losses of light by reflection and absorption being: dis- regarded). By giving values to / and = we obtain from the above formula the diameter d in millimetres. Under the assumptions made in the computation of the figures of the second column of Table IT. (i.e. % = 0°55 w and v = 2') we have a constant ratio of a: N, viz.:— a 1 : N ~2(264°5)’ and taking 7 = 250 mm. and substituting those values in the above formula we have A 90 = eae = 0°95 mm., consequently the same diameter d for all powers, and always the same brightness of the image therefore, provided the different _ apertures are fully utilized by the incident illuminating pencils. By increasing the values of a assigned for every power N by Table II. we enlarge the diameter of the emergent pencils in the same proportion; we should, for example, have d = 1:9 mm. throughout, if the apertures—so far as this is. possible—were in- creased in the ratio of 1 : 2, which would correspond to the assump- tion of a visual angle » = I’ for the least accessible detail. It is obvious, however, that larger apertures can be of advantage only so long as the value of d does not exceed the diameter of the pupil of the eye under the actual conditions of microscopical observation; for if this should happen, the iris of the observer must stop-off the marginal part of the lens-opening exactly in the same way as if a diaphragm were placed on the objective. The Relation of Aperture and Power. By Prof. Abbe. 471 Moreover, in microscopical observation—except under very faint illumination—the iris of a sound eye always contracts to a rela- tively narrow diameter, generally not more than 2 to 2°5 mm. Whilst, therefore, so far as delineating power alone is concerned, the largest useful aperture (for v = 2' as in Tables I. and IL.) is a 1 N N 2 (264-5) * ” = 529° plification of the Microscope will be given by the general formula above, if d is taken = 2°5. We then obtain, from a = d a the maaimum aperture for every am- N N a= 29" 500 ~ 200) and conversely N = 200.a as the minimum power required to enable the eye to admit all rays which emerge from the ocular. An aperture of 0°5 (60°) will therefore be useless in every respect (in regard to light as well as delineating power) as long as it is applied with powers of less than 100 diameters, and the same will be the case with an aperture of 0°25 (29°) for all powers below 50 diameters. Moreover, proper utilization of the rays which are admitted through a given aperture, will require still further restriction. For if the diameter of the pencils at their emergence from the ocular should closely approach the pupils’ diameter the least motion of the eye will cause a stopping-off of this or that portion of the aper- ture. The observer will therefore seldom utilize the full pencil, and will have the awkward sensation of a continual change of the illumination of the image. All this considered, it must be concluded that the wtmost amount of aperture which can be really useful under the general circumstances of microscopical work, will be, for every power, about twice the figures indicated by the second table. This corresponds to an increase of the emergent pencils to a diameter of nearly 2 mm. (1°9 mm). Every larger proportion between aper- ture and power must be considered as decidedly irrational, because it is not only waste of aperture in every respect, but at the same time a positive disadvantage for convenient and proper observation. Up to the limit here assigned, I admit the benefit of increased aperture, so far as the ower and lowest powers are in question, for which the other requirements—as has been shown—do not impose greater restrictions. In my opinion, the benefit of the increase is, however, not so much the gain of light by itself, but rather the ad- vantage, that narrower illuminating pencils, which do not fill wp the whole aperture of the objective, may be applied without incon- venient reduction of light. The smaller apertures which are sutti- cient for properly utilizing the delineating power of the objectives would also be quite sufficient in regard to light, provided the inci- 472 Transactions of the Society. dent beam always utilized the full area of the objective. In point of fact, a system of a = 0°2 (23°) applied with a power of 106 diameters will not show any want of light under that condition, even with dull daylight. The deficiency which, under all circumstances, is found in the use of high powers (notwithstanding correspondingly wider apertures) has no other cause but that we are not allowed to apply illuminating pencils as large as the full aperture of the Micro- scope. With the exception of some particular cases, the utilization of wide apertures in observing delicate objects will always require such narrower incident beams of light (generally of no greater angle than 30—40° in air) as utilize directly a small portion of the aperture- area only; the effect of the wider aperture being to collect those rays which are dissipated to large angles by the structural elements of the objects. The actual brightness of the image which is ob- tained under these circumstances is of course much less than it would be if an illuminating pencil equal to the full aperture could be employed. The proper effect of low apertures is, it is true, much less dependent upon the reduction of the illuminating beams. Nevertheless, such reduction—by means of diaphragms below the preparations—is an important benefit in many observations. or that purpose it is of practical importance that the aperture should be greater than would be required for the brightness of the image under full illumination. If twice the value of a assigned by Table II. is admitted for the several powers, these powers will still afford sufficient light, even if incident pencils of half the aperture only are used for illumination, and three-quarters of the clear area therefore is left for the utilization of dissipated rays. 4. We have now all necessary data for defining, at any rate in outline, a rational standard for the ratio between aperture and power in regard to the entire Microscope, i.e. the amplification of the ultimate image (without considering at present the participation of objective and ocular). (1.) So far as those apertures are in question which cannot at the present time be overstepped, the aim must be to obtain the most perfect performance for those powers which are just sufficient for the full utilization of the delineating capacities of these apertures. The figures of N assigned by Table I. may thus indicate the par- ticular aims for the various kinds of lenses—dry, water-immersion, homogeneous-immersion—in regard to those values of a which must be considered as the practical limits for these various systems (i.e. about 0°95 for the dry, 1°25 for the water-immersion, and 1:45 for the homogeneous-immersion systems respectively). For the full development of every system a reasonable latitude for further increase of power, beyond the limits of strictly useful powers, must, however, be left. The Relation of Aperture and Power. By Prof. Abbe. 473 (2.) So far as the medium powers are in question, which are below the limits of useful powers for the maximum apertures, but still above those amounts which could be obtained by very moderate apertures, a somewhat strict economy of aperture 1s indicated by important considerations in regard to the general demands of scientific work (penetration, working distance, &c.), because the disadvantage of superabundant aperture will be always greater than the possible benefit. For the medium powers in use, the figures of Table I. will therefore give the approximate limits of latitude which may be deemed reconcilable with a rational construction of the Microscope for scientific work. (8.) Concerning the lower and lowest powers, a gradually in- creasing latitude is left for the application of wider apertures than would be theoretically necessary in regard to the delineating capacity required for these powers. A surplus of aperture in- creasing up to about 100 per cent. for the lowest amplifications, will be in favour of the dl/wminating power of the Microscope; a considerably greater excess will at all events be mere waste.* * The concluding part of the paper—ii. Division of the Entire Power of the Microscope between Objective and Ocular—-will be printed in the next number of the Journal, 474. Transactions of the Society. XII.—Description of a Simple Plan of Imbedding Tissues, for Microtome Cutting, in Semi-pulped Unglazed Printwng Paper. By B. Wiis Ricnarpson, F.R.C.S.1., Vice- President University of Dublin Biological Association. (Read 10th May, 1882.) I am emboldened to publish the following description of a method for imbedding tissues of suitable consistence for microtome cutting, as it may have some claim to originality, imbeddmg in semi-pulped paper being unnoticed in any of the standard works on microscopic manipulation which I have had opportunities of searching. Be this as it may, very thin and perfect sections can be cut with rapidity in semi-pulped paper, from either animal or vegetable structures of sufficient firmness to remain uninjured while being sent home in the microtome well. I think, however, that im- bedding in semi-pulped paper will probably be found to have a more extended range of usefulness for vegetable section-cutting rather than for cutting animal structures. Although tissues submitted to the process should have a certain amount of firmness, as I have just observed, they should not, on the other hand, be so dense as to offer much resistance to the knife, very unresisting structures being unsuitable for this mode of imbedding. The diameter of the tissue to be cut should, when feasible, be one-quarter of an inch less than the diameter of the microtome well. Indeed, a microscopist’s laboratory ought to be provided ~ with microtomes haying wells of different diameters that both time and tissues may be economized. Stems of plants previous to cutting may, with advantage, be stored in methylated spirit for a few weeks; and animal structures, in whatever fluid has been found most appropriate for their pre- servation and, if necessary, for their hardening. I shall now give the steps of this easy method :— Cut strips, eight to nine inches long, from white unglazed printing-paper, the width of each strip to be a little more than the length of the structure to be imbedded. ‘Transfer the latter from the preservative fluid to filtered water, in which leave it for about half an hour, then dip one of the strips of paper in the water for a few seconds, remove it and drain the water rapidly off its surfaces. Take the structure to be cut out of the water, apply one end of the wetted paper to a portion of its circumference, and roll the paper around the structure as closely as the paper will allow of without tearing. If necessary, apply more wetted paper until both the paper and inclosure form a plug that should require a little Simple Plan of Imbedding Tissues. By Dr. Richardson. 475 pressure for sending it home in the microtome well. If too much paper has been applied, tear off the superfluous portion until the desired calibre is attained. The paper when wetted will, of course, stretch, but a little practice soon teaches the operator to roll it with only the tightness necessary for allowing the imbedded tissue to be cut without break. In careful hands dozens of perfect sections may be cut in half an hour from very delicate stems } of an inch in diameter, or from the delicate aereal-roots of certain orchids. But I should mention that a pine-apple stem of an inch in diameter has afforded me most perfect sections when imbedded in the semi-pulped paper. Up to the present time (April 1882) the only animal structures I have had leisure to imbed and cut in semi-pulped paper were decalcified human teeth, and a diseased external iliac artery removed from the body of a child, one of whose lower extremities I removed by amputation at the hip in March 1879. From the “dentinal cartilage” I obtained several thin and instructive specimens. The artery did not bear the knife to my satisfaction, having partially “rotted” from a too prolonged immersion in Miller's fluid. Further experience of pulped paper as an imbedding medium may lead to an extended use of the paper for animal-tissue section- cutting. But I prefer to conclude here, at all events, with a stronger recommendation in favour of pulped paper for supporting vegetable tissues in the well of the microtome under the restric- tions I have mentioned. It is almost superfluous to add that each section should be floated off the knife in water, and that a little of the latter should be carried by the blade to the semi-pulped paper in the well, to maintain it at the requisite degree of saturation for efficient cutting. The advantages which I consider the method to possess are :— (1) Facility in application ; (2) almost unlimited application in vegetable section-cutting under the restrictions above mentioned ; (3) rapidity in cutting; (4) the tissues are equally supported ; (5) cleanliness; (6) heat not being used, the subsequent staining of sections is more equal. 476 Transactions of the Society. XIII.— Note on the Rev. G. L. Mills’ Paper on Diatoms in Peruvian Guano. By F. Krrtoy, Hon. F.R.MS. (Read 14th June, 1882.) Tn the last volume of the Journal, p. 865, Mr. Mills has figured and described a new species of Auliscus, A. constellatus. After reading his description and carefully examining his excellent figures, I was satisfied that his species was identical with that described by Herr Janisch in his ‘ Zur Charakteristik des Guanos,’ Breslau, 1861-62, as A. Stockhardtiz; it is also figured in Schmidt’s ‘ Atlas der Diatomaceen-Kunde,’ Tafel xii. figs. 11-13. Schmidt remarks that fig 13 = “A. racemosus Ralfs (Gre- ville Monograph of the Genus Auliscus, T.M.S. vol. xi. 1863, p. 46, pl. iii. fig. 18) doch Janisch’s Benennung ist alter.” This is undoubtedly correct, and Ralfs’ specific name must be deleted. I communicated the result of my examination to Mr. Mills, who at once admitted the correctness of my views, and, moreover, had the kindness not only to send me the specimens of his sup- posed new species, but also most generously gave me his specimen of Aulacodiscus Kittont with fourteen processes. On examining this I congratulated myself on possessing a probably unique but certainly a very beautiful state of this species. Zxamining it again a few days afterwards, I found, in consequence of the balsam being still soft, that a valve of Aulacodiscus Comber had partially shipped over it. I resolved upon remounting it, and succeeded in placing it on another slide; during the process I caught a glimpse of the f.v., which induced me to examine it again very carefully with a binocular and + objective, when to my disappointment I found that our supposed fourteen processed A. Kzttone was composed of the two inner valves (each with seven processes) of a double frustule ; these were in close proximity—in fact, the two convex surfaces touched each other, the elevations on one surface fitting into the concayities of the other, thus accounting for the fact, noticed by Mr. Lewis, that the processes appeared “all in the same plane, and all equally and distinctly defined.” The number of processes in Aulacodiscus and Ewpodiscus are now generally admitted to be of no specific value, but it is more constant in some species than in others, e.g. A. formosus. I have never seen more than four processes, and on some valves I have observed as few as three, but in every case they were abnormal forms. In all other species the number is more or less variable. In a pure and recent gathering of A. Kittons I have seen no valve with more than six processes, four being the usual number, but abnormal forms are by no means rare. I have seen a six-rayed valve with four of the rays at right angles to each other, Diatoms in Peruvian Guano. By F. Kitton. 477 the remaining two being close to the opposite rays (processes). The most remarkable abnormally is a valve without process or avra€, but with the former faintly indicated near the margin. It is only right to add that these remarks on Mr. Mills’ paper have been written at his request, as he does not wish an error to remain uncorrected. 478 SUMMARY OF CURRENT RESEARCHES RELATING TO SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND: BO] snes (principally Invertebrata and Cryptogamia), MICROSCOPY, &c., INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS.* ZOOLOGY. A. GENERAL, including Embryology and Histology of the Vertebrata. Division of Embryonic Cells in the Vertebrata.t—L. F. Henné- guy, in studying cell-division as exhibited in the ovum of osseous fishes, finds that that of the trout, on the third or fourth day after fecundation, if treated with a mixture of acetic and picric acids, is the best adapted for this investigation; the cells are then seen to be formed of a finely granular protoplasm, and contain a nucleus of some size. The nucleus of acell in a state of repose contains a plexus, formed of small irregular granulations, which are especially well stained by carmine. The nucleolus is only a little larger than the other granu- lations. Soon there appears around a clear space, of which the centre is occupied by the nucleus, very fine clear lines, which are set along the rays of the cell, and which together form an aster; this aster elongates and becomes elliptical, as does also the nucleus; the aster then divides, and the two halves each form a fresh aster; at this moment the membrane of the nucleus disappears, and the rays of the aster penetrate into the interior. The plexus now breaks up into a number of small rod-shaped bodies ; these become set at the extremities of the rays, and form the so-called equatorial plate. Gradually the rods diminish in size but increase in number, and fuse to form a pectinate figure. The body of the cell then begins to be constricted in its middle, the rays of the aster disappear, and the connective filaments alone remain to unite the two nuclei, until at last the cells become completely separate. The new nucleus, due to the fusion of the rods, is highly refractive, and is intensely coloured by reagents ; * The Society are not to be considered responsible for the views of the authors of the papers referred to, nor for the manner in which those views may be expressed, the main object of this part of the Journal being to present a summary of the papers as actually published, so as to provide the Fellows with a guide to the additions made from time to time to the Library. Objections and corrections should therefore, for the most part, be addressed to the authors. (The Society are not intended to be denoted by the editorial ‘‘ we.”) + Rey. Internat. Sci. Biol., ix. (1882) pp. 363-5, ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 479 as it increases in size, there appear the limiting membrane and the internal plexus. At a later stage of development, when there has been multiplica- tion of the cells, these become smaller and smaller, and the asters gradually become quite indistinct. In the earliest stages of segmen- tation the process of division is more difficult to follow, owing to the large size and very granular contents of the cells; on the first and second day the cells become so uniformly tinted that the nuclei are with difficulty made out. As the cells diminish in size the action of the colouring matter becomes more and more confined to the nucleus, and the author is of opinion that the chromatin of Flemming is at first uniformly distributed through the cell, and that it gradually separates to form a constituent of the nucleus. Genesis of the Egg in Triton.*—Mr. T. Iwakawa records the result of observations on the genesis of the egg of the common Triton (T. pyrrhogaster Boje), in which he describes the manner of depositing the egg (the female turning upside down so as to place it under the leaf or stem), the structure of the ovary, origin of the ovum and Waldeyer’s “epithelial islands” (the author’s view being that the ovum does have an epithelial origin), the formation of yolk- spherules, the vitelline membrane, the germinal vesicle, and the “ yolk- nucleus.” Formation of Fibrine.t|—In 1879 Dr. Norris described the alleged discovery of a third corpuscular element in blood in the form of colourless disks, which he considered to be an earlier stage of the red corpuscles. { This was criticised by Mrs. Ernest Hart in the fol- lowing year, § her view being that they were red corpuscles that had undergone post-mortem changes prior to taking part in the formation of fibrine. Continuing her investigations and repeating the experiment of “isolation ” || a great number of times, she began to observe that the appearances changed according to the length of time which elapsed between the spreading of the layer of blood between the two glass surfaces and the moment when the cover-glass was raised, and thus discovered that a whole series of phenomena could be traced, leading from the pale or colourless corpuscle up to the complete formation of networks or bands of fibrine. In developing this method of working it was found that the staining reagents recommended by Dr. Norris were not sufiiciently powerful to bring out all the details that could be observed on the glass surfaces, and after many trials a highly con- centrated solution of nitrate of rosanilin in absolute alcohol was found to be the best staining reagent. The method adopted was to detach the cover-glass from the slide after the corpuscles had been fixed by osmic acid vapour, and to examine both the surfaces of the cover-glass and the slide, to see which presented the most perfect preparations. * Quart. Journ. Micr. Sci., xxii. (1882) pp. 260-77. + Ibid., pp. 255-9 (1 pl.). t See this Journal, iii. (1881) pp. 229-32. § Loc. cit. || See description, loc. cit. 480 SUMMARY OF CURRENT RESEARCHES RELATING TO Having made a selection, a drop of the concentrated solution of nitrate of rosanilin was deposited on the glass and allowed to remain for a few moments, and then washed off with a fine jet of distilled water. The red, pale and colourless corpuscles, with their ramifications and the most delicate fibrils of fibrine, then become visible under a high power. The preparations may be mounted dry, and will keep for a great length of time. If the process be performed as rapidly as the dexterity gained by an oft-repeated experiment will allow, it will be observed that the circular appearance of the corpuscles is perfectly preserved, and that every shade of colour may be found, from the normal red corpuscles down to the colourless Norris corpuscle, which only takes the faintest tint of pink. If, however, the glass surfaces be allowed to remain in contact for a moment, the colourless cor- puscles are found to have lost their globular form, and to have become pyriform or elongated. On leaving the glass surfaces still longer in contact, these pale corpuscles are observed to undergo a remarkable change. They send out long processes or tails, which bifurcate and divaricate in every direction. On allowing a still longer interval to elapse, so that itis more than probable that coagulation would occur in a film of blood lying between two glass surfaces, and on separating these surfaces, perfect specimens of fibrine may be obtained after staining. On now searching the field, the pale corpuscles, which could formerly almost always be discovered, are nowhere to be found, and the conclusion is forced upon one that the branching corpuscles have developed or broken down in fibrinous threads. Small granules are, however, found from which threads of fibrine appear to spring. These granules are described in Ranvier’s ‘Traité Technique d’Histologie’ as the centres of fibrine formation. They appear to the author to be all that is left of the pale corpuscles, whose intermediate transformations have not before been recognized, but may perhaps be identified with the appearances and changes described. Amongst other figures, one is given showing the departure of the fibrils of fibrine from the pale corpuscles. New Blood-corpuscle.*— According to G. Bizzozero, if the circu- lating blood in the small vessels of the mesentery of chloralized rabbits or guinea-pigs is observed under a high power, there will be seen, besides the ordinary red and white cells, a third form of cor- puscle which is colourless, round or oval, and from one-half to one- third the size of the red corpuscle. He considers that they have hitherto escaped the notice of observers (1) owing to their translucency and want of colour; (2) because they are less numerous than the red, and less visible than the white corpuscles ; (3) owing to the great difficulty of observing the circulating blood in the small vessels of the warm-blooded animals. They can be seen also in freshly drawn blood, for the most part aggregated around the white corpuscles, or immediately under the cover-glass, to which they adhere. They soon become granular, and give rise to what is called the granule- masses. ‘Through appropriate reagents their form can be preserved. * Arch, Ital.de Biol., i,(1882) pp. 1-4; cf.‘ The Microscope,’ ii. (1882) pp. 59-60. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 481 A solution of salt coloured with methyl-violet has this property. The best method of examining them in the human subject is to place a drop of the above coloured solution over the puncture and mix the drop of blood thoroughly with it. Owing to their typical forms, it is very unlikely that they are derived from the red corpuscles. The colourless corpuscles contain no ingredients from which they could be derived. After bleeding, and in many diseased conditions, they are increased in numbers. They play an important part in the formation of thrombi and the coagula- tion of the blood, which has been attributed by Mantegazza and Schmidt to the white corpuscles, because the latter are few in number in the circulating blood, and their destruction was never observed by Bizzozero, provided the blood was mixed with a saline solution, Again, the time at which coagulation sets in corresponds very closely to the time that these new corpuscles undergo degeneration. The fluids which retard or prevent coagulation—as solutions of carbonate of soda and sulphate of magnesia—have the same action in pre- venting the granular degeneration of these corpuscles. An indif- ferent solution of salt does not preserve them, but one to which the methyl-violet has been added does. From this evidence it appears (to the editor of the ‘ Cincinnati Medical News’) highly probable that the formation of fibrine takes place under the direct influence of these corpuscles. To them Bizzo- zero gives the name of “ Blutplattchen.” Life and Death in the Animal Organism.*—After completing an important investigation on the “ Earliest developmental operations in the ovum, on cell-division, and on conjugation in the Infusoria,” O. Biitschli, early in 1876, wrote an essay headed “ Thoughts on Life and Death,” but he left it unpublished, considering, on the one hand, that his ideas on the differences between Protozoa and Metazoa in respect of the phenomena of death were too recently acquired to be made known, especially in print, and that, on the other hand, the speculations which he had associated with these ideas were too immature to be made permanent. His fundamental views, however, namely those relating to the non-existence of individual death in the Protozoa, have now been published. “Tf we glance over the phenomena of the origin and destruction of beings in the great series of animal organisms, we are astonished by a significant contrast in the importance of individuality in the higher, i.e. the many-celled, as compared with the lower, i.e. the uni- cellular, forms, the Infusoria or Rhizopoda. Whilst in the first the individual, in almost all cases, asserts an existence definite and distinct even from its progeny, in the unicellular forms, on the contrary, which reproduce by fission, we are met with the fact (which does not usually receive much attention) that at the time of reproduction the individual, as such, ceases to exist, and divides its individuality equally between the individualities of its two offspring, which now come into existence. This remarkable phenomenon * Zool. Anzeig., v. (1882) pp. 64-7. Cf. Naturforscher, xv. (1882) pp. 125-6, Ser, 2.—Vor. II. 2K 482 SUMMARY OF CURRENT RESEARCHES RELATING TO appears in the most striking light when we endeavour to realize in these lower forms the idea of death, such as we have been led to consider it from observations of the higher animals. Death in the higher organisms is not the total extinction of life, but only of the individual existence; bat the reproduction of a unicellular organism constitutes at the same time its death. On the other hand, however, by the idea of death in the higher organisms is implied an actual separa- tion of organized substance from the activity of life, in other words, an annihilation of previous life. This element is entirely wanting in the individual death of the Protozoa, that is, in its reproduction ; it goes on living all the same, though in the persons of its progeny. If we study the development of certain Protozoa,—the Infusoria,- — we come upon the highly remarkable fact that death does not occur in them, in the sense of annihilation of organic material and from causes inherent in the organism itself. Although these organisms, in the course of their life, are threatened by death under a thousand forms, yet this takes place by “accidents,” and thus the few individuals which reproduce the species are to be considered of equal importance with the multitude which perish, for the few reproduce by fission only, and are thus immortal; while the many which die could have repro- duced their species just as well as the others, if they had had the same favourable opportunity; not one of them necessarily carries in it the seeds of death. Whoever wishes to construct a hypothetical representation of the fact that in the higher animals the individual is limited in its dura- tion to a certain time, will find a tolerably simple plan open to him. If we hold it to be allowable to consider the peculiar vital manifesta- tions of the cell, the fundamental element of every form of organiza- tion, as caused by the presence of a substance which acts in a certain sense like a ferment,—necessary to the production of those chemical changes in the cell which result in vital manifestations, but gradually, though perhaps slowly, used up,—then the limited duration of the life of one of the higher animals may be intelligibly represented by assuming that the ovum out of which this organism once originated acquired a certain amount of this ferment-like substance, which is gradually exhausted during life, and with the final exhaustion of which the end of the individual existence coincides. It is otherwise with the Protozoa, which reproduce by simple division. These organisms have also this characteristic vital ferment, but they also enjoy the peculiarity of being able to renew it ; hence it is not exhausted in them, and they are not overcome by death in con- sequence of its being used up. But the power of forming this vital ferment is shared by the higher organisms as well, but here it is localized, being confined to the generative organs. In the other cells composing the body the material we have been speaking of is gradually and increasingly used up in the course of their active existence; but in the generative regions, whose cells maintain their primitive character longest, fresh vital ferment is accumulated for their posterity. Certain appearances occur which, perhaps, justify us in forming an approximate idea as ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 ' to the place in the cell which this material with its property of evoking life occupies. Among these the chief are the phenomena of conjugation of Infusoria, taken in connection with facts recently acquired in the study of the process of fertilization in the Metazoa. The gradually diminishing vital energies of the Infusoria are strengthened afresh by conjugation, and this comes about by a partial or total renewal of the nucleus from the so-called nucleoli or primary nuclei. A total or partial renewal of the nucleus of the ovum is also seen in fertilization, and it is most probably effected by the spermatic nucleus. (This passage was written in 1876, when the first and imperfect account of the process of fertilization had just been put forth; but it would be easy to alter it so as to bring it into accordance with our present knowledge, without interfering with the part played by the nucleus.) Thus the failing vital powers of the Infusoria are raised up again by the renewal of the nucleus, and a similar result occurs in the process of fertilization; is it not, therefore, a justifiable conclusion that the vital ferment which has been spoken of, actually resides in the nucleus of the cell, whenever this is present. It is not the whole nucleus which is to be interpreted in this way, but only a small part of its bulk. Thus in the case of the Infusoria, it must be assumed that the freshly produced life-ferment is collected more especially in the so-called nucleoli, but in higher organisms in the reproductive cells, chiefly in the nucleus of the male reproductive elements.” N. Cholodkowsky, in discussing * the doctrine of Biitschli, points out certain difficulties in the way of our accepting this view. Some forms, e.g. Hydra, have an asexual as well as a sexual method of reproduction ; now, if all the cells of such an animal have the power of producing new individuals they must all be immortal; yet, as a matter of fact, we know that many die down. It seems to Cholod- kowsky that the cause of the death of the Metazoa is to be sought for in the multicellularity of their organism. A cell has in itself and for itself a potential immortality; but as soon as differentiated cells are united into an individual there commences amongst them a struggle for existence, which, eo ipso, leads to destruction. The hypothesis of Butschli recalls the Darwinian doctrine of Pangenesis ; just as Darwin supposed a general distribution of reproductive cells throughout the organism, which only later became concentrated in the generative cells, so does Butschli deal with his vital ferment, and the doctrine of the latter is therefore only a more physiological way of expressing that of Pangenesis. Pelagic and Deep-Sea Fauna.jf—T. Fuchs enumerates the distinguishing characteristics of the pelagic and the deep faunas respectively, and makes some inductions as to the reasons for these peculiarities. Pelagic animals are those which are wholly indepen- dent of the shore and the sea-bottom at all stages of their existence. * Zool. Anzeig., v. (1882) pp. 264-5. ‘ + Verh. k. k. Geol. Reichsanstalt, 1882, pp.49 and 55. Cf. Naturforscher, xv, (1882) pp. 199-202. ae 2 484 SUMMARY OF CURRENT RESEARCHES RELATING TO Most of them are transparent and colourless, and thus invisible in water; where colour occurs, it is usually violet or blue, resembling that of the water; the fishes are chiefly stcel-blue above, silvery-white below. Most forms are naked; the shell, if present, is comparatively delicate. A large number are viviparous, even when their nearest allies are oviparous. A great number of pelagic animals are phosphorescent. Nearly all are admirable swimmers. Some have their surface-area largely developed, e. g. the tests of Radiolaria, of Globigerina, Hastigerina, &c., probably in order to hinder sinking. As to the manner of life, they are almost without exception social, they mostly have a very wide distribution, and are found alike in the Atlantic, Indian, and Pacific Oceans; the genera are almost all identical in these seas, although polar seas are distinguished from warmer waters by possessing few forms besides Crustacea, Pteropoda, Cephalopoda, and Cetacea. In connection with their usually delicate structure stands the fact that it is only in the calmest weather that they live on the surface; storms may drive them to a depth of more than 50 fathoms. Further, far the majority only come to the surface in the night, a point to be con- sidered in connection with the prevalence among them of phosphor- escence; the time of appearance of the phosphorescent fish is more often connected with the night than with any other time. Pelagic animals seldom occur except over deep water, and at great distances from coasts, hence their scarcity in the German Ocean, their poverty in littoral and their abundance in deep-sea deposits. The deep-sea fauna is distinguished by the appearance or pre- dominance of certain individual species, genera, and families, and exhibits little variation in the different parts of the world. It com- mences at a depth of about 50 fathoms in all seas, but it is only in the tropics that anything like a sharp line of demarcation is found between it and the littoralfauna. Examining these points to ascertain the reason for a bathymetric limit of this particular nature, Fuchs finds that it cannot be due to temperature, although this diminishes as the depth increases, for in the Red Sea the warm zone extends much below 50 fathoms, while in polar waters even the surface has a low temperature, and currents operate besides so as to introduce great irregularity into the bathymetric relations of temperature ; however, the fact that 48 to 50 fathoms has been ascertained to be the limit to the penetration of light into the sea appears to him good evidence that the presence or absence of light is the determining agency sought for, and that the littoral fauna is simply the fauna of the light, the deep-sea fauna that of darkness. ‘This view is supported by the more superficial distribution of deep-sea forms in some places in which the limit of light lies at an inferior depth, and the deeper range of littoral forms in fresh waters, where the light has greater penetration. The large eyes or blindness of so many, the pale or monochromatic colour of most, and the phosphorescence of a large number of the animals which compose this fauna is evidently connected with the absence of light. The resemblance of the pelagic to this fauna is intelligible if it is remembered that it too is most in its element in ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 485 the darkness. Resemblances between cave faunas and that of the deep-sea point also to a common cause in the absence of light. The range of some littoral forms into great depths may perhaps be found to be due to their being nocturnal in habits. The cavities which occur under coral reefs off Brazil may perhaps shelter a fauna of deep-sea character, owing to the absence of light there; hence it would be not unlikely that geologists might find similar aggregations of deep-sea animals in formations otherwise composed of littoral reefs. Otherwise the relations of deep and littoral faunas were probably much the same in geological times as now, owing to the similarity of their relations to the light, and the differences here indicated can, in point of fact, be traced throughout all formations. B. INVERTEBRATA. Mollusca. Anatomy and Classification of the Cephalopoda.* — Dr. J. Brock commences with a study of Rossia, the knowledge of the anatomy of which is confined to the short description given by Prof. Owen. Asa result of the new investigations we find that Rossia is, as has been supposed, most closely allied to Sepiola ; the relations of these two forms to the Myopsida, and especially Sepia and Loligo, are by no means so clear. The author’s earlier investigations led him to the belief that the affinities of the different forms might be well shown by this diagram :— Sepia. —Rossia——_——Sepiola. —Loligo. —Ommastrephes, The presence, however, in Rossia, of fused lower salivary glands points to its affinities with the Cigopsida, and this would lead us to form a table in which Loligo should stand above Rossia, or nearer Sepia. As to the relations of Sepiola to the form last named, it might be supposed that Sepiola had branched off from the Decapod stem independently, but the Octopod characteristics of Sepiola, as seen in its musculature, are to be found also in Rossia, and it requires evidence of a kind very different from that which we have at present to lead us to believe that these very similar arrangements could have been independently developed by the two forms. The Octopod type of the musculature of Rossia is still further developed in Sepiola, and that in a way which justifies us in regarding the latter as a direct descendant of the former. A useful table is given in which are enumerated twelve characters and the respective resemblances and differences of Ommastrephes, Rossia, and Sepiola. If the view that Rossia and Sepiola form a line of development which branched off from the Decapod stem shortly before Loligo be * Zeitschy. f. wiss. Zool., xxxvi. (1882) pp. 543-640 (4 pls.). 486 SUMMARY OF CURRENT RESEARCHES RELATING TO correct, we find in it what may be spoken of as parallel-developments ~ with the Myopsida and Octopoda; we find, that is, in this side branch a series of differentiations which have, for the different organs, _ a most remarkable resemblance in those two series. Just as from Loligo to Sepia, so from Rossia to Sepiola we find the upper salivary glands lost, the accessory nidamental glands fused, the efferent duct of the ink-bag sharply marked off, and the lateral teeth disappearing from the middle plate of the radula. From Ommastrephes to Sepia, just as from Rossia to Sepiola, the fused lower salivary glands are separated, and there appears a characteristic arrangement. of the ova in the duct. Likewise, there is in Sepia and Rossia a shortening of the inner pallial nerves, which finds its termination in the absence of these in Sepiola on the one hand, and the Octopoda on the other. A very instructive diagrammatic table is given by the author to demonstrate the points on which he insists. If we enter into still wider generalizations, the facts observed by the author lead us to see that in the Dibranchiate Cephalopoda, long before the separation of the phylum into the Octopoda and Decapoda, there must have been a tendency, under suitable, though still un- known, conditions, for the cartilaginous articulations with the mantle and funnel to yield to firmer membranous or muscular cephalic joints ; thrice, or twice at least, did this tendency exert its influence. In connection with this there must also have been a tendency to the reduction and final loss of the upper salivary glands, the separation of the lower ones, and the fusion of the accessory nidamental glands. Dr. Brock then passes to a second study of the generative organs of the Cephalopoda; in dealing with the female organs of the Cigopsida it is pointed out that the nidamental glands may be absent, as in Enoploteuthis, or that they may be present, with (a) the oviduct lying ventrally to the gills, as in Ommastrephes sagittatus, or (6) the oviduct may open with a buccal invagination of the integument, lying dorsally to the gills, as in Om. todarus, Onychoteuthis, or Thysano- teuthis. A study of the generative organs of the Philonexide shows, us that they may be thus arranged :— 1. Subfam. Hectocotylifera. ¢ with a free Hectocotylus. a. Philonexide S. Str. Hectocotylus without dermal frills. No water-vascular system—Argonauta, Philonexis. b. Tremoctopodide. Hectocotylus with dermal frills. A water-vascular system—Tremoctopus. 2. Subfam. Parasiride. Free hectocotylus not known, but pro- bably present. @ with very long oviducts, viviparous. Parasira. - In dealing with the gland of the oviduct, it is pointed out that — the following series may be detected in the Octopoda :— 1. Gland consisting of a series of ceca arranged radially around the oviduct; no increase in the extent of the secreting surfaces —Argonauta. 2. The secreting surfaces of the gland well developed, and a ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 487 circlet of strongly developed receptacula seminis interpolated between the gland and the oviduct—Tremoctopus violaceus. 3. The receptacula seminis not so well developed; a fresh gland developed between them and the primitive gland—Parasira catenu- lata. 4, No receptacula seminis; the walls of the primitive and of the secondary gland highly developed, and in the latter so far advanced as to lead to a fusion of the glandular sacs—Octopus, Eledone. Various as are the forms of the oviducal gland in the Octopoda it is important to notice how uniform they are in the Decapoda. The author then enters upon a consideration of the so-called water-canals and the viscero-pericardiac cavity; he finds that the genital capsule of the Octopoda is the (reduced) direct homologue of the viscero-pericardiac cavity of the Decapoda; and that the water- _ canals of the Octopoda correspond to the anterior, while the genital capsule corresponds to the hinder portion of the viscero-pericardiac cavity of the Decapoda. And he concludes with accounts of Tremoctopus ocellatus n. sp., Octopus pictus n. sp., Loligo bleekeri, and Cranchia reinhardti. Ink-Sac of Cephalopoda.*—P. Girod publishes a full and detailed account of his study of this organ.f By a careful dissection, first of the peripheral trabeculze, and then of the apex of the pyramid formed by the formative zone, we come upon the cellular mass which forms the central portion of the trabecule. When a portion of the tissue of this part is teased out, elongated cylindrical cells may be detected which, in their general character, are not unlike the cylindrical cells of many mucous membranes; the large nucleus which occupies the narrower end of the cell becomes very apparent on the addition of colouring reagents. The cell itself, on high mag- nification, is found to be divisible into two portions: the larger of these is coloured yellow by picrocarmine, and seems to be formed of a hyaline liquid, which is limited on the nuclear side by a faint, slightly concave, and granular line ; the second and narrower portion contains a granular protoplasm. The constitution of the cell sug- gested to the author that it belonged to the calyciform series, but the absence of any orifice did not seem to him to justify that view. Near these cells others may be seen which contain black granula- tions in their upper portion; these are not cylindrical, but are divided by constrictions into three portions ; the uppermost colour- ing matter is bounded externally by the cell-membrane, and is also distinctly separated from the nucleus. On the whole, there is a very close connection between these and the cells of the first set, the hyaline mass in the latter being now filled with pigmented granula- tions, and the part which contains the nucleus having been elongated. Other cells present other characters ; in some there is a much larger aggregation of pigment, whence two lateral prolongations descend, one on either side of the nucleus: here, too, slight pigmented granu- * Arch. Zool. Expér. et Gén., x. (1882) pp. 1-100 (5 pls.). t See this Journal, i. (1881) pp. 227, 586, and 876. 488 SUMMARY OF CURRENT RESEARCHES RELATING TO lations are to be seen within the substance of the nucleus. In others the black granulations are so richly developed as to completely obscure the nuclear mass, although that body is still present. Finally the cells commence to undergo degeneration, their membrane breaks, and the pigment escapes ; the nucleus, however, still persists, and it is in consequence of this that we find free nucleated masses in the midst of the pigmented granulations. The author discusses in order the histological characters of the meshwork, the wall of the pouch, its internal, median, and external tunics. Turning to the development of the ink-sac, we find that on the fourth day of the second period (that of the development of the organs) the anal depression comes in contact with a process of the mesoderm, and then divides into two portions, the superior of which is the ink-sac, and the inferior the rectum. The former rudiment has at first a transverse direction, and extends from the anal orifice to the internal yolk-sac, and is clothed by a single layer of epithelial (ecto- dermic) cells. This is what will form the vesicle. The cells at the cecal extremity soon begin to multiply and form a thickening which is the rudiment of the gland. The glandular mass developes rapidly by making its way into the midst of the mesoderm; the cells of that layer now begin to form peripheral layers around the gland, till they nearly completely surround it, and the mass becomes divided into two lobes, between which there is an extension of the mesoderm. Changes in the cells themselves now appear, and give rise to the formation of a thick granular liquid. As soon as the glandular cavities are developed the investing cells take on the characters which belong to the formative zone of the adult, and a peripheral and a formative zone are thus developed. Further changes bring about a connection between the gland and the reservoir; the latter then begins to increase rapidly in length, and at the same time to dilate. Still further changes, in the mesoderm, give rise to the different investing layers, and there is some alteration in position. Looking more generally at the matter, we find that the ink-sac is formed by an epidermal invagination, which, during development, is differentiated into two parts, the gland and the vesicle (reservoir) ; this invagination is contained in a kind of mesodermic sac, which forms the tunics that envelope the epithelium ; the innermost of these consists of an epithelial and of a connective layer, the median of the silvery and of a muscular layer, and the outer of connective tissue. When we compare this with the integument, we cannot but be struck with the remarkable similarity between them ; there, too, we find an epithelium, the cells of which are arranged in a single row, and limited externally by a thick cuticle; the connective layer contains the chromatophores, and beneath this there are a silvery layer, muscular fibres, and a layer of connective tissue. The absence of chromatophores in the region of the sac may be explained by a study of the intermediate stages presented by different parts of the body. The researches of Lacaze-Duthiers on the purple-glands of certain Gastropoda have led the author to make a study of these structures, from which it results that their anal gland is homologous with the ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 489 ink-sac of the Cephalopoda, and this view is strengthened by a consideration of the nervous supply. In the Gastropoda the glands in question receive filaments from the “‘ asymmetrical centre,” in the Cephalopoda the nerves come from the visceral or inferior ganglion which corresponds exactly with that centre. If we compare the ink-sac of the Octopoda with that of the Deca- poda we find that there is in the former an arrest of development, the reservoir not being elongated or widened out; in consequence of this close relations still obtain between it and the anal orifice, and the gland and reservoir are closely applied to one another. It is to be borne in mind that the tetrabranchiate Cephalopoda are without the organ, and that it is only some of the Gastropoda which possess one, and that that one is always much simpler in character. The physiology of the question is also dealt with, and it is pointed out that three stages may be distinguished in the excretion of the ink: (1) there is a continuous passage of ink from the gland into the vesicle—due to a vis a tergo, and to the compression exercised by the limiting membrane of the gland and the nodosity of the vesicle; (2) an intermittent passage of the ink from the vesicle into the sac, due to the contraction of the vesicle; (3) spasmodic expul- sion of the ink by the funnel, due to the spasm of expiration. The nerve-branches from the visceral nerves were found to be motor filaments, presiding over the contraction of the wall of the vesicle. Sense of Colour in Cephalopoda.t*—How highly developed the sense of colour is in insects has been shown by Sir John Lubbock in his interesting observations on bees, wasps, and ants. For the development of the same sense in animals of a different type C. Keller brings forward evidence taken from the cuttle-fishes, which manifest in a high degree the power of adapting the colour of their skin to that of the environment. Keller was able to observe this adaptation of colour in Eledone. In the Naples Aquarium a specimen of this Octopod was under the necessity of flying from a powerful lobster; during its flight it appeared pale red ; but subsequently, resting on a tuft of yellow rock covered with brown spots, it imitated the yellow ground- colour with its brown spots so closely that it became almost invisible to the observer. In this case the conditions were decidedly very favourable for the occurrence, for yellow and dark-brown colour-cells occur in Eledone in large numbers. It should be added that the eye of the cuttle-fish shows an unusually high development. ‘Foot’ of certain Terrestrial Gastropoda.t—Mr. J. Wood- Mason describes the structure of the part of the foot called by German writers on malacology the Fuss-sawm which, as no technical name for it appears to exist in the English language, he proposes to call the peripodiwm, in allusion to its relation of position to the locomotor ventral surface or foot of the molluscs possessing it, but which he thinks may be homologous with the lateral folds (epipodia) * Vierteljahresschr. Naturf. Gesell. Zurich, xxvi. (1881) p. 100. Cf. Natur- forscher, xv. (1882) p..40. + Proc. Asiatic Soc. Bengal, 1882, pp. 60-2. 490 SUMMARY OF CURRENT RESEARCHES RELATING TO of many marine molluscs (Haliotis, e. g.). Very frequently the peri- podium is provided at its posterior extremity with a capacious pit, the capacity of which may be increased by the prolongation upwards of its anterior margin in the form of a horn, which not being specially sensitive is not a tentacle, often it is without this terminal pit; it is invariably richly ciliated throughout from the mouth on one side round to the mouth again on the other side dorsally; equally in- variably is it limited off from the side of the body (and frequently also from the muscular foot) by a peripheral groove, which deepens anteriorly. Its office is to assist in lubricating the foot, the pit when present receiving the effete lubricating fluid and throwing it off in gelatinous lumps. The foot-gland, as is well known, pours out its abundantly ae constantly flowing secretion through an aperture which is situated below and a little behind the mouth into a hollow whence it naturally falls into the deep anterior end of the dorsal peripheral groove, whence again it is carried by the cilia with which the surface of the peri- podium is beset (being distributed to the foot as it goes) to the terminal pit. In those forms in which this pit does not exist, the secretion that has served for lubrication is merely left behind by the crawling mollusc. As Pulmonata possessing a ciliated peripodium with and with- out a terminal pit are to be found in every quarter of the globe, and as it is in the highest degree improbable that so highly specialized a structure, subserving such an important purpose in the animal economy as this evidently does, has arisen independently many times in many different forms in many widely separated areas of the earth’s surface, the author considers that it has a higher taxonomic value than has hitherto been assigned to it, and he feels strongly inclined to distinguish those forms that possess it and those that do not (or have lost it) from one another by calling them Craspedophora and Lipocraspeda respectively. Mucin of Helix pomatia.*—According to H. A. Landwehr, when the mucin of Helix pomatia is treated with 1 per cent. sulphuric acid, it yields grape-sugar, whereas mucin from other sources yields only a reducing substance. The grape-sugar cannot be derived from glycogen, since the iodine reaction fails entirely in the freshly expressed secretion, and in the mucin prepared from it. The author however, succeeded in obtaining a carbohydrate, for which he propeses the name “achrooglycogen.” In order to prepare it, he directs that the mucin obtained from the snails shall be treated with 5 to 10 per cent. caustic potash, and the proteids separated by Briicke’s solution (potassiomercuric iodide), the solution filtered, and the filtrate pre- cipitated by alcohol. The material thus obtained, after being washed with absolute alcohol and dried, is an amorphous, white, “tasteless powder, readily soluble in water. The solution is strongly opalescent, gives no iodine reaction, and does not reduce an alkaline copper * Zeitschr. f. Physiol. Chem., vi. (1882) pp. 74-8. Cf. Journ. Chem. Soc. Abstr., xlii. (1882) p. 708. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 491 solution. By boiling with acids, or by digestion with saliva or diastase, the substance is converted into dextrin and grape-sugar. Rhodope veranii.*—Professor L. Graff gives an account of this form, which was regarded by Schultze as a Turbellarian, and named Sidonia elegans; he has been able to demonstrate that it is not a worm, but the Nudibranch long ago described by Kélliker under the name of Rhodope veranii. The largest examples are about 4 mm. long, with a breadth of } mm. The integument consists of a single stratum of cylindrical epithe- lial cells, and is pretty closely invested by long cilia; this integument is pigmented, and a figure of the curious arrangement of the colour, under what the author regards as its typical form, is given. Cal- careous spicules, of some size, are to be found under two different forms, embedded in the parenchyma of the body. The mouth lies at the anterior end, but is sometimes held dorsally ; the cavity into which it leads is provided with closely appressed small papille, but there is no indication of anything like a radula. After some account of the other parts of the digestive system, of the nervous system, and of the generative apparatus, Dr. Graff states that, like Kélliker, he searched in vain for any indication of a heart or blood-vessels. The numerous small oval corpuscles which fill the ccelom were suspended in a colourless fluid, which appears to be set in motion by the move- ments of the body, or the contractions of the enteron. The author was, however, enabled to discover a water-vascular system similar to that of the Platyhelminthes. Strong magnification revealed actively moving flagella, scattered through the body, and similar to those which are found in the excretory system of various Vermes. Each flagellum is continued in a vesicular enlargement, and by its widened base completely closes the ciliated funnel, the free end of the flagellum being directed towards the efferent canal. No exact information can be given as to the branchings of the excretory system, or as to the character of its orifices. The absence of gills, buccal mass, and radula, as well as of a vascular system, proclaims Rhodope to be the very lowest of all known Nudibranchs; at the same time it is distinguished from the allied Turbellaria by its anus, by the structure of its generative organs, its central ganglia, and its sensory apparatus. Rhodope must not, however, be supposed to have been derived from the present specialized Dendreceela, but from a group of Rhabdoccelida, to which, in his forthcoming Monograph of the Turbellaria, the author intends to apply the term Alloioccla; this group will contain Vorticeros and others, and will be distinguished from the Accela and the true Rhabdoccela by characters which will, we think, be better understood when that subject comes before us. Molluscoida. Test-Cells in Ascidian Ova.t—These cells, so characteristic of the ova of Tunicates, obtained their name from the belief that they * Morph. Jahrbuch, viii. (1882) pp. 73-83 (1 pl.). t Zool. Anzeig., y. (1882) pp. 356-7. 492 SUMMARY OF CURRENT RESEARCHES RELATING TO eventually formed the test enveloping the Ascidian. This view was shown to be erroneous, and Professor J. P. McMurrich now enunciates a new theory as to their function.* The latest theories on the subject of parthenogenesis and of the nature of polar-globules are based on the assumption of the bisexual nature of the ovum, on account of which it is possible, and there is even a tendency, for a yolk to divide spontaneously. In most cases this is disadvantageous, and the formation of “ test-cells” is a means of guarding against the misfortune. On the exposure of the ova to sea-water or other abnormal condition a contraction of the yolk is brought about, and thereby a tension upon the nucleus, which, under the strain to which it is subjected, would divide, and so start the pro- cess of segmentation, were that strain not removed from it by the extrusion of the test-cells, whereby it is preserved intact until the proper stimulus in the shape of a spermatozoon excites it to a healthy and normal division. This theory the author would also suggest as an explanation of the Excretkorper described by Hertwig and Oellacher as appearing in the ova of Amphibia and fish respectively, and also of the fatty globules described by the late Sir Wyville Thomson as occurring in the eggs of Comatula, to which structures test-cells bear no little resemblance. Embryology of the Bryozoa.t—J. Barrois finds that the larva of a Bryozoon consists essentially of five principal parts; an aboral surface, the peripheral pait of the oral surface with the corona which is only the edge of it, the incubating pouch with the central part of the oral surface which is destined to form the intra-tentacular space, the intestine, and lastly, the rudiment of the polypite which already exists in the larva, where it forms a special organ, and takes more or less a part in the formation of the polypite. In the Entoprocta these parts have most nearly the arrangement which is found in the adult; the aboral surface forms the integument of the larva, and the oral is retractile and can be withdrawn into the vestibule; the only change necessary to convert the larva into the adult is a rotation of the incubatory pouch and the intestine so as to bring them into relation with the rudiment of the polypite. In the Chilostomata there is developed, by the aboral growth of the corona, a pallial cavity ;—as the oral surface has here lost its retractile power, there must be a change in the position of the mantle before the larva can pass into the adult condition; here, therefore, there is a more marked metamorphosis. In the Ctenostomata the pallial cavity is enormous, and the cells of the corona are of very large size ; in the Cyclostomata there is no corona, but the oral surface continues to grow towards the aboral pole; and here, therefore, we have, in its most marked condition, the process which has become more and more * Tn a previous paper he showed that the test-cells were produced by a con- traction of the yolk of the ovum, consequent on the action of various stimuli being formed, more or less distinctly according as the stimulus was capable of causing a greater or less contraction of the egg-contents. + Journ. Anat. et Physiol. (Robin) xviii. (1882) pp. 124-61 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 493 marked the further we are removed from the Entoprocta; in con- sequence of this the oral surface, which was at first entirely enclosed in the interior of a cavity (the vestibule) and covered over by the aboral surface, has gradually passed more and more to the exterior so as to form by itself the external integument and to drive the aboral surface into the interior of a cavity (the pallial cavity). In the most differentiated types of the Chilostomata and Ctenostomata we have seen that the aboral surface has been driven into the interior; not- withstanding this, the uppermost portion of this surface which forms the organ called the “ calotte” has always been seen to be projecting. In the Cyclostomata, however, the pallial cavity is always closed and covered over. Adding to these the Lophopoda, we may make the following table: eaniaee Predominance of the aboral surface. Vestibule “oh cle a oO lg ak cla at its maximum. Intestine well developed. Chilostomata and Gah erates of the corona. A pallial cavity. Ctenostomata (sac reduced) The intestine reduced to a mass of globules. Cyclostomata and { Predominance of the oral surface. Pallial cavity Lophopoda (no sac). at its maximum. Intestine disappeared. The author points out that from the point of view of larval forms only we seem to find an essential character in the antagonism of the two great cavities at the poles, and, when we carry this further, in the greater or less development of the mantle. It is according to the ex- tension of this last that we find one or other of the two surfaccs of the larva best developed; when there is a median extension of the mantle we find, moreover, that the intestine has partly disappeared ; while when it is at its maximum condition of extension there is no intestine at all. When we come to look at the matter in a more general way we see that this development of the mantle is not a matter of so great importance, inasmuch as every form of larva, no matter to what type it belongs, can always be referred to a common type, in which there is no mantle, in which the oral surface is always within the vestibule, and the aboral forms an integument. The history of the mantle is, then, only a history of a series of adaptive modifications. Dealing with the mechanism of the metamorphosis, M. Barrois finds that if we try to construct a general type of adult Bryozoon we have to recognize (1) a foot corresponding to the oral pole, (2) the frontal surface, corresponding to that which answers to the oral, and (8) a tergal or anal surface. In the Entoprocta these can be easily made out, but in the Ectoprocta it is not always so distinct; in the forms where the zocecium is elongated we seem to have the primitive dis- position, in the flattened ones the tergal surface is increased in extent ; palingenesis is to be seen in the Ectoprocta, coonogenesis in the Entoprocta. As the author regards the Bryozoa as belonging to the Vermes he notes that, with the exception of the Rotifera, the Bryozoa are the only Vermes in which a telostomiate condition is con- stantly manifested, either in the larval or in the adult condition; in other words, the division of the body is on the primitive or gastrula 494 SUMMARY OF CURRENT RESEARCHES RELATING TO type, in which we see an oral and an aboral pole. A free-swimming Entoproctous larva is then formed on the same type as a Rotifer. Granting this, we must suppose that the Bryozoon is the result of a simple change of life; we know that these larvee often creep about on their oral surface. If this habit were to become permanent we should have in the change of habits a sufficient cause for the meta- morphosis ; the ciliary current carrying food to the mouth would, on passing it, abut against the anal extremity of the vestibule, and would gradually drive this back towards the superior extremity of the larva ; there would thus be produced the rotation, in which the digestive tube would be implicated. We may assume the earlier existence of a group of Probryozoa, free-swimming creatures, of a general Rotifer- form, only represented to-day by the larvee of some of the Entoprocta ; these on taking to creeping would have their form altered by a current of water. Her , New Adriatic Bryozoa.*—Dr. Piesser discovered in some material sent him from Rovigno in the Adriatic a Bryozoon, which he found difficult to determine on account of its having some of the characters of Gemellaria and some of Notamia, but he calls it Gemellaria, and considers that the definition of the genus must be widened to receive it. It consists of rows of double cells back to back, and the aperture occupies most of the front. A zocecium does not spring immediately from the zoccium below as in Gemellaria loricata, but grows in the manner of Notamia bursaria; further, at the commencement of each branch instead of a pair of zocecia, there is only one, out of which a pair grow. There are radicle fibres which start from the back of a pair of cells and grow out independently, instead of uniting together and growing in a bundle down the dorsal surface of the colony. The most perplexing point to Dr. Piesser was the occurrence of avicularia at the top of the zocecia, sometimes sessile and very minute, at others they are much larger and pedunculate. He thinks that these characters show that it is a connecting link between Gemellaria and Notamia, and if his interpretation is correct, about which opinions may perhaps vary, we may look upon this as another instance showing that the presence or absence of avicularia cannot often be relied upon for generic division. It may interest Dr. Piesser to know that although this curious species has not previously been described, yet it lives in the Bay of Naples, and has also been found from a locality outside the Mediterranean. Arthropoda. a. Insecta. Sensations of Sight conveyed by the Facet-eye.j—The experi- ments of Grenacher, Dor, and Exner, as to where the rays received by the compound eye of Insects ought to be and are concentrated, led to the most contradictory results, until Grenacher finally established the true view. Several points, however, as to the quality of the * Neunter Jahresber. Westfalisch. Provinzial. Vereins fir Wiss. u. Kunst, 1881. + Abh. Senckenberg. Naturf. Ges. xii. (1880) pp. 35-123 (3 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 495 function of vision still required investigation. The close parallel with the Vertebrate eye which was attempted to be drawn, is quite fallacious. -Clearness of sight was said by Joh. Miller to coincide with long sight, and to be best exhibited in those eyes which have the greatest circumference—the greatest number of very small facets, large crystalline cones and dark pigment-mass; the nearer the object to the eye, he said, the clearer the view obtained of it. Dr. J. Notthaft believes the size of the facets and the length of the radius of the curve of the eye to be the only factors in its structure which have an important bearing on this point. With regard to the effect produced by the presence of a number of receptive and refractive units—the units of the compound eye—he believes that the edges of the units and fields of sight are in contact ; when the curve of the eye is perfectly spherical the fields are approxi- mately polyhedric, like the facets, but when the curve is eccentric, distortion appears as magnification increases. The smallest angle of sight is constituted by the angular distances between the directions in which two neighbouring retinal elements look, or even between two such ocular elements regarded as wholes. A few examples may be given of the actual condition of things in some specific eyes :— Difference a of istance at direction | yo, of Smallest Breadth Heading which the between F ei ‘S Angle of of Cn Sight-field two aces: Vision. Facets. Eve of a unit terminal of Eye = ent elements. mm. mm. Apis mellifica .. | 1042 | 54 |1° 56’ (or 0° 51)*| . -024 10-78 ‘| 67 cm. Formica rufa 51° 35 |1° 97° (worker) Sphinx convolvuli | 67° 39 | 1° 43’ Acherontia atropos| 20° VS or Sai nor 0° 42) 5 e037 3:0 81 cm. * Determined by calculation from the radius of the eye-sphere as compared with the breadth of a facet, In spite of its large minimum angle of vision, the insect eye affords, under certain circumstances, as great an amount of distinct- ness of vision as the human eye, or even greater; for there is no minimum limit to the distance of vision, and objects near the eye are seen more clearly than anywhere else; the distinctness of vision diminishes as the square of the distance from the eye: these relations for the following insects are :— Distance in mm. at which Amount of Clearness with a the Clearness Distance of =I. =0'1, 0. | 60 cm. Apis mellifica .. .. 1°35 177 3°36 0-000024 Sphing nerti 4. os 0°81 8°51 1:67 0:000035 496 SUMMARY OF CURRENT RESEARCHES RELATING TO The indistinctness produced by distance has the effect of reducing the image of (e.g.) an Ailanthus leaf to an outline in which the different lobes are almost entirely merged together, and almost all the detail lost (cf. Figs. 88 and 89). Exner’s view of the impression produced on the insect eye of the degree of rapidity of movement in any objects, viz. that it is inti- Leaf of Ailanthus glandulosa, showing part taken by the different portions of the compound eye in viewing it. Fic. 89. Effect produced on the retina by the leaf thus viewed. mately connected with the movement of the insect itself, must lead to absurd conclusions. Joh. Miiller’s view, that insects see objects only by means of the accurate perception of their illumination, is the most important point in the theory of mosaic sight (that of ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 497 compound eyes), and contains the key to its principle. Only those rays of light can affect the eye which fall on it in the radial direc- tion, i.e. in the direction of the long axes of the crystalline cones. Each retinula (retina of a single unit) receives a cylindrical bundle of light-rays from every visible object; exactly the same amount of an object is taken in, at whatever distance it is viewed, so the effect of motion is not produced by an increase in or reduction of the amount which is seen of a moving body. The action of direct sunlight on insects is evidently, from their sensitiveness to it, of great importance to them. Seeing that the angle which the rays proceeding from the orb of the sun make on reaching the earth is on the average 32’, the smallest angle of vision for a unit of any insect’s eye being probably more than 10’ (39' is the lowest known to the author, viz. in an Aischna), the single image of the sun would be spread, at the most, over three unit-eyes, and, at the least, over one ; while the minute unit of the human eye, having an angular distance of 10" only, can take in ;1, of the sun’s disk, and thus the disk occupies in the retina a surface 192 units in diameter, and covering about 27,000 rods. The amount of light which can be received directly by the facetted eye from the sun is far less than that received by the human eye, in fact only from 5,1, to »7boo of the amount received in the latter case. The bearing of this * striking fact on the habits of the insect is difficult to see, but it may be asserted that the insect’s eye is thus well provided against the effects of a too intense light, while its sensibility to minute grades of illumination from terrestrial objects remains incontestably one of its most important properties. For by far the greater amount of the impinging light is absorbed by the epidermic structures, and owing to the spherical curvature of the eye, the rays which reach it coincide in direction with the optical axes of but a few of the units, and so but a small portion of the receptive nervous region is affected by them ; thus only the ;yy%so0 part of the sun’s disk is perceived by a single eye. This view is supported by Grenacher’s opinion that it is the median (i.e. direct and unrefracted) rays of the pencil which strike a facet, which are the most important. The perception of an object in all its dimensions and of its relation to surrounding bodies cannot be learned, as it is to some extent in our own case, during the short life of the insect. Some idea of the character of the insect’s vision may be gained from the observed fact that the natural impulse of the insect is to court the darkness (e.g. the lower sides of leaves, the shade of grass, &c.), in order to avoid observation; their well- known delight in brilliant illumination forming merely an episode in their life of caution. Probably they are to some extent subject to optical delusion; thus when the sun suddenly goes behind the clouds, the surrounding objects, before so brilliantly illuminated, would appear to be at a greater distance, owing to their loss of light. To ascertain the relations of objects with regard to the surrounding space is the most important function of this organ in these animals, and especially the relation of distance from the eye itself; these ends are attained by the comparatively large angular distance which Ser. 2.—Vo.. II. 245 498 SUMMARY OF CURRENT RESEARCHES RELATING TO the closely apposed elements present. The actual distinctness of the features of the object is less important here than with the human eye. The reason for the existence of two forms of eye, simple and com- pound, in perfect insects, is that of separating the impressions of space and distance from those of distinct sight of the object (the latter end being attained by the stemmata or simple eyes). Four, on the whole strongly distinct, kinds of vision are differentiated in the animal kingdom :— 1. General sensation of the amount of light evolved in the environ- ment and of the relative position of its source ; analogous to our sensa- tion of warmth, and exhibited only in small organisms with trans- parent outer coverings, and devoid of special portions of the body adapted for the function. 2. Sensitiveness to colour and shades of colour; general orientation as to environment, power of recognizing known objects—the “eye-spots” of Vermes, &c. 3. Information as to relative positions of surrounding objects affording guidance of movements, with slight amount of guidance as to characters of object—compound eye of Arthropoda. 4. The most clear and faith- ful perception of the objects, the images reversed by a lens which strongly refracts light. The contents of a plane are the subject of this kind of vision, which does not convey to the brain the distance or mutual relations of objects ; the plane may be either single, at a constant distance from the eye, or there may be several at distances which vary within certain limits, as when accommodation comes into play. In this case the third dimension, viz. depth or distance of objects, is obtained by movements made by the eye-bearing individual, relatively to the objects viewed, materially aided by the power of accommodation, when this is present; in its absence, as in the case of the stemmata of Arthropoda, this impression must be very feeble, since the moving animal obtains nothing but a disconnected series of images of the objects as they come one by one within the range of its organs, “The phylogeny of the compound eye is deducible from the fact of the acquired character of the movements of Arthropoda; as the faculty of motion became better developed, the organs of sight became modified, pari passu, into that form which successfully met the requirements of this mode of motion, in the manner above explained; the highest degree of development being naturally reached in the Insecta. All winged insects are thus provided, while but few of the wingless forms, such as larve, &c., have this form of eye. The explanation of the peculiar character of the vision enjoyed by the compound eye lies in the lenticular curvature of the corneal facets, which do not act as Joh. Miller supposes, by magnifying the entering rays, but by admitting only those which are not likely to prove injurious; this appears to be shown by a comparison of the Insect with the Crustacean eye. The latter is remarkable (judging by the results obtained by Grenacher from Mysis) for its large angle of vision—3° 16’ in the instance taken—and is probably fitted to convey impressions from a distance not exceeding a metre. Taking into ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 499 consideration the density and other light-absorbing properties of the medium in which the insects live, the amount of light received from an object must vary approximately as the cube of the distance of the source of light, hence the wide opening of the eye, admitting as much light as possible. The same effect as the perspective which is obtained in air is here produced by the indistinctness of objects, owing to the opacity of the medium, in proportion to their distance from the eye. The structural causes for these differences are :—(1) the flatness or slight curvature of the Crustacean cornea, which does not hinder the entrance of any light which falls radially upon it, and (2) the strong convexity of the facets in insects, which causes refraction of the rays to a focus in front of the retina, and consequently a dimi- nution of the light which meets them; thus most of the hurtful rays —those whose direction is not exactly at right angles to the surface of the cornea—having entered the eye at its side, are again thrown to the side and absorbed by the walls and the pigment of the narrow tube, whose diameter at the apex only allows of the entrance of a small central pencil. With regard to the fate of strongly divergent rays, the refractive properties of the cornea would appear calculated to increase their brightness ; but this is the case only with objects at short distances, and has the advantage of giving distinct and recog- nizable images of objects within this range. Nervous System of the Strepsiptera.*—The nervous system of the Strepsiptera has not been subject to any special researches. C. Th. von Siebold ¢ only states that these insects (Xenos vesparum) have one thoracic ganglion ; but he does not say anything about the number of cephalic and abdominal ganglia. HE. Brandt’s researches have been limited to four females and one male of Stylops melitite, and one female Xenos vesparum, preserved in spirit, the results of which are as follows :— 1. The cephalic division of the neryous system consists of the ganglion supra-cesophageum only, the ganglion infra esophageum being absent. 2. The thoracic division consists of a large ganglion containing five pairs of nuclei; it is divided into two parts, an anterior and smaller one, corresponding to the ganglion infra-esophageum and to the first thoracic ganglion of other insects, and a posterior and larger part, which corresponds to the other thoracic ganglia and to some abdominal ganglia. The interior division supplies nerves to the organs of the mouth (like the ganglion infra-cesophageum) and to the first pair of legs. The posterior and larger division of this ganglion supplies nerves to the second pair of wings, to the thorax, and to different segments of the abdomen. 3. The abdominal division of the nervous system consists of one abdominal ganglion, situated in the last third of the body. It is * Abstract by the author of a memoir in Russian, St. Petersburg, 1878. Ann. and Mag. Nat. Hist., ix. (1882) pp. 456-7. ¢ Lehrb. d. vergl. Anat., i. (1848) p. 582. 24 2 500 SUMMARY OF CURRENT RESEARCHES RELATING TO oval, and is connected with the thoracic ganglion by means of a long thin cord. From this ganglion spring three pairs of nerves, of which the first and second pairs branch out in the fifth and sixth segments of the abdomen, while the last pair branch out in the last segment of the abdomen and in the rectum. This nervous system is as curious as that of some Coleoptera (Rhizotrogus solstitialis, Serica brunnea) and some Hemiptera (Hydro- metra lacustris), as it has no ganglion infra-cesophagewm. Insects which injure Books.—Professor A. Liversidge, of Sydney, sends us some specimens of Lepisma saccharina, and points out that “in Blades’ ‘ Enemies of Books, 3rd ed. (1881) pp. 61-3, he refers to the description of a book-worm in Hooke’s ‘ Micrographia’ (1665), and rather makes fun of the figure and description there given— ‘certainly R. Hooke, Fellow of the Royal Society, drew somewhat upon his imagination here, having apparently evolved both engraving and description from his inner consciousness.’ - People living in New South Wales and other of the warmer parts of Australia can, however, bear testimony to the accuracy of Hooke’s statements and drawing. The insect figured in the ‘ Micro- graphia’ abounds here amongst books and papers, and is wonderfully destructive to them. It does not do so much harm to books as it does to loose papers, maps, labels, &c., as it cannot well get in between the closely pressed leaves of a book, and it is on this account that the loose edges of piles of MS., bundles of letters, &c., suffer so much more than the central portions; writing paper, too, probably contains much more attractive matter in the way of size, &c. With this I enclose some scraps of paper showing the ravages of the insect (Lepisma), and also some of the ‘silver fish’ themselves, by which name they are commonly known here and also in India, whence I understand the name ‘silver fish’ originated. The destruction of labels is a very serious one, as the identity of a specimen may very soon be lost. The labels enclosed have only been written about fifteen months, and some hundreds have thus been rendered totally useless. In future it will be necessary to saturate the labels with a poison, such as corrosive sublimate. At times I have thought that, perhaps, the ‘silver fish’ instead of doing harm may be doing good—for wherever they are found we are likely to find pseudo-scorpions (chelifer), and it may be that the former prey upon the latter; though I think not.” Formation of Galls.*—M. W. Beyerinck finds that “ galligenesis ” affects a portion of the vegetal tissue, which becomes altered in character, and may then be known as galliplastema ; the galligenetic influence is due to the larve and not to the hymenopterous parent. The phenomenon of formation of the galls is absolutely indepen- dent of the lesions which the deposition of the eggs causes in the living tissues of the plant. Direct contact between the animal and the plant is not necessary for the production of the galliplastema ; there may be a layer of dead cells, or even the covering of the egg * Rev. Internat. Sci. Biol., ix. (1882) pp. 373-4. ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 501 between them, and this intermediate space may be greater than the diameter of the larva. In the cases in which the animal that produced the gall had originally only one point of contact with the galli- plastema, the further inclusion of the larva is due to an annular investment of the plastema, which increases in extent and becomes folded over it. A temporary contact on the part of the larva does not produce a gall. The larve are fed by the development in the gall of a tissue the cells of which have thin walls and contents rich in oil and albumen. In their anatomical structure many of the galls have characters which appear to be completely foreign to the organization of the plants that nourish them. y. Arachnida. Anatomy of Phalangida.*—Dr. R. Réssler finds that the digestive system consists of three portions, of which the spacious midgut is provided with a large number of ceca; the sucking action is pro- duced by a layer of strong transversely-striated circular muscles, which is only continued on to the more anterior portion of the succeeding oesophagus; the lumen of this latter region is almost completely filled up by six longitudinal folds, consisting of a trans- parent cuticle with a subjacent layer; the cells of the salivary glands may be seen, in section, to form one layer and two smaller complexes below the cesophagus; the secretion has an acid reaction. All the thirty ceca are without a muscular investment, and consist only of a thin fat-layer, a tunica propria, and an epithelium; the Malpighian vessels are represented by two tubes, forming a loop, which are placed near the median ventricle, and open not into the intestinal tract, but into two sacs on the ventral surface of the animal. The genital organs of the two sexes are referable to a common plan, consisting as they do of an unpaired germinal gland, semicircular in form, lying freely in the body-cavity, and only surrounded by a rich supply of trachez ; there is connected with this gland a paired efferent apparatus, which however becomes united into an unpaired piece, and finally opens to the exterior in the median ventral line, between the cephalothorax and the abdomen. Connected with the terminal portion is a copulatory organ, into the anterior portion of which there open a pair of accessory gland-organs ; the penis is rod-shaped, the ovipositor is cylindrical, and the vagina has a seminal pouch on either side. The testis is a simple tubular organ about 4 mm. long and 0:4 mm. wide; the spermatozoa are large, biconvex, rounded cells, with a lens-shaped nucleus ; the vasa efferentia commence as two fine canals, and soon form a close coil; the cells of the lumen become commingled with the products of the testis; the propulsion-organ has a thick muscular layer, the fibres of which are transversely striated, and there is a thick chitinous layer secreted by the epithelium; the lumen of the ductus ejaculatorius is narrow; chitin is also to be found in the penis. The ovary is horseshoe-shaped, invested by transverse and longitudinal muscular fibres, and when mature is beset with a * Zeitschr. f. wiss. Zool., xxxvi. (1882) pp. 671-702 (2 pls.). 502 SUMMARY OF CURRENT RESEARCHES RELATING TO large number of follicles of variousages. These, which may be looked upon as evaginations of the tunica propria, all contain an egg, more or less developed, but the ova are always of small size until they make their way into the uterus, which then attain their full size and development. In the immature female the uterus 1s only apparent as a slight outpushing of the oviduct, but at the period of maturity it becomes turgescent, swells out, and occupies a large portion of the body-cavity ; itis provided with a powerful layer of circular muscular fibres, and its inner surface is lined with cells, similar in character to those of the vas deferens. The terminal portion of the vagina is surrounded by a system of chitinous rings; the ovipositor, like the penis, is surrounded by two sheaths, which are essentially of the same structure in all the species. The two glands at the lateral margins of the cephalothorax have been regarded by Loman as stink-glands; the author finds that in Opilio albescens there is an aromatic odour, which he ascribes to these organs. Scent-glands of the Scorpion-spiders (Thelyphonus).*—The re- markable Arachnidan genus T’helyphonus is confined in its distribution to South America and Southern Asia and their islands. Of its internal anatomy nothing but the nervous system is known. The French zoologist Lucas states that the Thelyphom are called Vinai- griers by the inhabitants of Martinique, on account of the strong vinegary odour which they emit when touched or handled. Stoliczka, who examined living specimens of one of the Indian species, states that a peculiar but inodorous fluid issues from two internal pyloric (!) appendages. These Arachnids, according to Lucas, live in damp places under stones on the ground. Stoliezka and Mr. Peal found them beneath the bark of decayed trees in groups. Mr. J. Wood-Mason, who has undertaken an investigation of their anatomy, was only able to obtain specimens for dissection during the heaviest rain, when all vegetation and the ground is saturated with water, and the animals come forth from their holes in the rocks. He found that death quickly followed their removal from their humid haunts, air saturated with moisture being apparently necessary for the due performance of their respiratory functions. All the specimens he met with emitted, when touched, a most powerful and lasting odour, exactly like that of a highly concentrated essence of pears, which when deeply inspired had all the characteristic smell and pun- gency of strong acetic acid. This odour did not emanate from the general surface of the body, but proceeded from a pellucid fluid which exudes from the neighbourhood of the anus and is secreted by special glands. These are paired and tubular organs of huge size, extending from the nineteenth somite of the body (on which they open by two minute valvular apertures placed at the sides of the anus) to the front end of the thirteenth in the male, but to the middle of the eleventh in the female (whose glands are consequently the larger), and being, with the exception of the voluminous liver, the most conspicuous of the viscera. They are two subpellucid bags, shaped somewhat like * Proc, Asiatic Soc. Bengal, 1882, pp. 59-60. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 503 an Indian club, striped longitudinally with white, and filled to dis- tension with a thin clear fluid. They are not quite equal, nor are they placed symmetrically in the body-cavity, but the one or the other lies between the nervous chain and the ventral body-wall in the middle line between the two rows of vertical muscles, and the other between the row of muscles and the lateral wall of the side of the body to which it properly belongs. They apparently consist of a strong and structureless basement membrane, invested externally by a layer of delicate striped muscular fibres arranged circularly, and of an inner membrane; the walls of the short (1 mm. long) ducts are transversely thickened so as to resemble the trachew of insects; the granular tissue is arranged between the two membranes in longi- tudinal plated stripes, so as to permit of the expansion of the lumen of the tubular organ in a receptacle or bladder for the storing up for use of the secreted fluid, to which apparent arrangement of the granular substance the striped appearance of the organs is due. The secretion doubtless serves to protect the animal from attack, and it is interesting to find that the female in this, as in so many other animals which are similarly protected by their offensive odour, is (as being for obvious reasons the more important sex) more perfectly protected than the male by having, not indeed, so far as could be detected, a stronger and ranker, and therefore more disagree- able scent, as in many insects, but larger scent-secreting glands. Another point of interest brought out by this investigation is that the two glands exhibit a tendency to coalesce and form a single unpaired median organ, the two being always unequal and occasionally partially united and the one in the middle line invariably the larger. These structures seem to belong rather to the category of excre- tory organs than to be highly developed skin-glands; and they are probably homologous with the silk-glands of other Arachnida and of Insects, with the green-gland of the Crayfish, and with the segmental organs of Worms and Peripatus. 5, Crustacea. Classification of the Brain of Crustacea.*—Dr. A. S. Packard gives the following provisional grouping of the brain of Crustacea, which he considers to be justified by known facts, although excepting the brains of Decapoda and Limulus, no special histological work has been accomplished. The terms archi-cerebrum and syn-cerebrum have been proposed by Professor Lankester, the first to designate the simple worm-like brain of Apus, and the second the composite brain of the Decapoda, &e. Decapoda. Tetradecapoda. Syn-cerebrum ( Phyllocarida. Cladocera. Entomostraca. Phyllopoda. Archi-cerebrum {Metta (Limulus). Cirripedia ? * Amer. Natural., xvi. (1882) pp. 588-9. 504 SUMMARY OF CURRENT RESEARCHES RELATING TO The syn-cerebrum of the Tetradecapoda, Amphipoda, and Isopoda, judging by Leydig’s figures and his own observations on that of Idotea and Lerolis,is built on a different plan from that of the Deca- poda. The syn-cerebrum of the Phyllocarida is somewhat like that of the Cladocera and Copepoda (Calanidz) ; being essentially different from that of the majority of the Malacostracous Crustacea. ‘The Copepodous brain is an unstable, variable organ, but on the whole belongs to a different category from the syn-cerebrum of other Neocarida. We have then, probably two types of archi-cerebra, and three types of syn-cerebra among existing Crustacea. Unpaired Eye of Crustacea.*—In most Crustacea, besides the two compound eyes (fused together in the Cladocera), there exists an unpaired median eye. It exists alone in most of the Copepoda, and in all naupliiform larve. Wherever the two kinds coexist in the adult but not in the newly hatched larva, the unpaired eye is the first formed, and must therefore be regarded as the primitive eye of the Crustacea. By thin sections of Cyclops and Diaptomus, Mr. M. M. Hartog has ascertained that this organ is of a much more complicated composition than had been supposed. The pigmented mass is, so to speak, structureless; the colouring-granules in it are placed at the surface contiguous to the “crystalline spheres.” Hach sphere is com- posed of radiating elements, the inner ends of which are applied against the pigmented mass, while the peripheral segments contain a nucleus. The eye is situated upon the terminal process of the brain, from which the optic nerves originate, one for each sphere; the nerve, instead of penetrating into the pigmented mass, skirts the outer surface of the crystalline sphere, and penetrates it directly not far from its hinder margin. The author has also found in the Phyllopoda a perfect analogy of structure with that just described in the Copepoda, and therefore concludes that the unpaired eye in all the Crustacea that possess it, is composed of three simple eyes, placed anterior to the brain, with reversed optical bacilli, receiving conductive fibres of the optic nerve upon their outer margin, and brought so close together that their pigmented or choroid layers are combined in a single mass. A nearly identical structure may be detected in the Chetognatha, which have the triple eye of the Crustacea; but, instead of being median and unpaired, it is repeated on the two sides of the head ; certain Planarians, Dendrocelum lacteum for example, have two paired eyes, which, according to Carriére, have the structure adopted by the author for one of the simple eyes united in the median eye of the Crustacea. It is probable that the eye of the Chetognatha and Crustacea is to be referred back to the type of the Planarians, but that the two former groups have no direct relationship between them. Blood of the Crustacea.t—G. Pouchet is reported to find that the differences seen in the blood of these animals is not, as Wharton * Comptes Rendus, xciv. (1882) pp. 1430-2. + Journ. Anat. et Physiol. (Robin) xviii. (1882) pp. 202-4. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 505 Jones thought, due to differences in the time of year. Their blood is remarkable for the large quantity of sea-salt which it contains, a drop from a Maia laid on a glass slide and dried giving a large number of crystals. Coagulation takes place very rapidly. Notwithstanding the great variation in form of the leucocytes, it is possible to re- cognize a common type; a large number have the form of young blood-corpuscles of oviparous vertebrates; as they grow older they present a number of granulations, and, as their nucleus is then often small or altogether lost, the author is of opinion that the granular condition represents the last stage in the development of these bodies. The form and the size appear to differ considerably as we pass from one species to another; the form, which is always ovoid, appears to be permanent so long as the blood is retained within the circulatory cavities; as an example of this we may cite the case of Palemon, where the leucocytes found in the lateral lobes of the telson did not, during a long period of examination, exhibit any amceboid changes. Pyloric Ampulle of Podophthalmate Crustacea. *—F. Mocquard describes the ampulle as forming the floor of the median part of the pyloric duct; in most cases they may be compared to two demi- cylinders placed side by side, with the cavity upwards. The surfaces are not, however, regularly cylindrical, for they are rounded and truncated obliquely behind. Their inner edges unite to form a pro- jecting longitudinal—interampullar—fold; from their cavities and from the sides of the fold there arise a large number of parallel longitudinal crests, on the free edges of which there are rows of ex- tremely fine sete; from this arrangement there results a considerable number of small prismatic canaliculi, directed from before backwards ; the free edge of the posterior portion of each of these ampullar crests is continued into a large seta, which is directed backwards and carries extremely fine sete. A remarkable point in this arrangement is that very slight differences are found even when the Stomapoda are com- pared with the Decapoda. Similar ampulle are to be seen in the larvee (and doubtless also in other forms) even when there is no gastric armature; while further, though absent in the Mysis, they are to be found in the Mysis-stage. We never find any appreciable amount of food in the ampullar cavities, and their functions would appear to be this: while the nutritious matters which are difficult of digestion remain in the superior portion of the pyloric duct, the more finely divided par- ticles make their way between the interampullar fold and the side- wall of the pylorus along a line parallel to, but in a contrary direction to that of the sete; they are thus broken and brought into a sufficiently fine state to enable them to penetrate into the canaliculi, whence they pass backwards in a longitudinal direction. In support of this view, the author directs attention to the fact that the excretory ducts of the so-called liver empty their products not far from the posterior orifice of the canaliculi, where the alimentary matters and this secretion would therefore be brought into intimate contact. * Comptes Rendus, xciv, (1882) pp. 1208-11. 506 SUMMARY OF CURRENT RESEARCHES RELATING TO Heterogeny of Daphnia.*—C. L. Herrick, in the course of re- searches upon the development of Daphnia Schaefferi (= magna), observed several interesting facts. The embryo, before leaving the egg, in both summer and winter forms, is furnished with palpi on the base of the second antennz, and a long appendage from the dorsal region of the shell. The former, though quite large in the embryo, is later nearly atrophied, remaining during life, however, as a wart-like process with two rather small spines. The latter is curved beneath the body, lying between the valves of the shell. After the escape of the animal from the egg this organ becomes the dorsal spine, and seems to serve as an aid to the complete moulting of the walls of the brood-cavity, with the first development of which the spine seems also to stand in intimate relation. It is worthy of remark that not only the mature animal, after long confinement in aquaria, becomes smaller and stouter, and in other peculiarities resembles the smaller spined species of Daphnia, but that the young retain the dorsal spine and the shorter form till in a sexually mature condition, when in confinement. This fact, and the discovery of Dr. Birge, that the spine upon the head of another species of Daphnia is also an embryonic organ, serve to call attention to the systematic position of this genus. It would therefore appear that the species Schaefferi is the culmination of a cycle of forms, among which are to be counted more or fewer of the species described as distinct. Daphnia thus furnishes another example of so-called “ Heterogeny.” Notodelphyide.j—W. Giesbrecht describes the female repro- ductive organs of these parasitic Copepoda. ‘The ovarian tubes are completely differentiated before the last ecdysis, when they present the following features; there is a structureless tunica propria lined by a simple epithelium, the cells of which are as broad as high. As changes occur, this epithelium becomes separated off from the wall of the tube; the process commences at the anterior end, and gradually passes backwards, so that in a series of sections the anterior ones are filled with the separated cells, while the lumen of the hinder ones is still open and the wall invested by epithelium; the cells do not break off separately but in longitudinal rows. When this process has come to an end, the walls of the tube are formed by a distinct membrane, which is lined by a layer of protoplasm; at first the nuclei in this latter are at some distance from one another, but they soon come to form groups of two to six. The tube, therefore, first had the function of a germ-producer, and may be called the ovary, while, later, it serves as an oviduct, and affords nutriment to the growing ovarian cells. Owing to their coming off in longitudinal rows, the ova now lying in the tube are arranged in cords of a cylindrical form, each of which may have as many as one hundred eggs; there is no investing membrane to these ovarian cords. A little later the * Zool. Anzeig., v. (1882) pp. 234-5. + MT. Zool. Stat. Neapel, iii. (1882) pp. 293-372 (8 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 separate cells begin to be distinguished from their neighbours; many of them increase in size by the growth of their peripheral portion, and the internal contents of these do not therefore become altered in character. Others develope within themselves fatty bodies. Under the influence of the growing ova the paired portions of the ovarian tubes increase greatly in diameter, and soon after this the eggs make their way into the maternal cavity, where they pass through the stages of development prior to the Nauplius condition. The dorsal folds are chiefly formed of a connective tissue, which consists largely of membranous elements and partly of spindle-shaped fibres, which may be regarded as muscle-cells; in addition to these there are rounded fibres, which extend from one surface to the other. Rounded or ellipsoidal bodies are to be found lying in the meshes of the tissue, filled by a very regularly arranged polyhedral meshwork of very delicate membranes. A number of fatty cords traverse the appendage in a radial manner; these are processes of the fat-body which is so frequently found in parasitic Crustacea and are here particularly well developed. The investing membrane is a continua- tion of the general chitinous covering of the body, though it is here more delicate than in other regions. As there is in all essential points the very closest agreement between the structure of these folds and that of the other parts of the body, it would be better to speak of them as processes of the body-cavity, than as dermal folds. The specially modified portion which serves as a brood-pouch has its internal lamella formed by a specially thick chitinous membrane, and is at first so folded as to allow of the increase in size of the cavity which becomes necessary later on. Some of the habits of these forms are treated of in detail, and it is pointed out that the first copulation commences before the final ecdysis of the female, but the attachment of the spermatophores only becomes completed after the ecdysis; in this action of the male, the appendages, and specially the fourth or fifth pair of feet, take part. Various males may fertilize the same female who remains completely passive during the whole act. ‘The reason of this apparently prema- ture copulation is considered, and the suggestion is made that it is an arrangement derived from an earlier condition in which the female did not pass through the last ecdysis. The succeeding acts of oviposition and delivery are described ; they are repeated at regular and constant intervals, whereas the later acts of copulation are not so definitely arranged. A female who has just deposited her ova, has a thin, faintly-coloured, hardly detectable ovarian tube; five days afterwards this is again filled, and the red eye-spots of the embryos in the brood-cavity can be made out. After ten days from oviposition, the embryos are ready for extrusion, and again the ovarian tube will be found full; for about two and a half days the brood-pouch remains empty. The author does not look upon the development of the fat-body as an arrangement which owes its origin to the struggle for existence, but as a passive necessary result of the parasitic habits of these animals; the assimilated nutriment which the free-living forms use 508 SUMMARY OF CURRENT RESEARCHES RELATING TO up owing to their activity, has no use in an organism which lives a parasitic life; and the physiological process is therefore completely similar to that which obtains in fattened cattle. ' The earlier part of the paper is taken up by (1) an account of the presence of these forms in certain Ascidians, the author only finding them in Phallusia mentula, and P. mammillata, where they are far from being the only guests; (2) a description of their external form ; and (8) a systematic account of the species, which are arranged under the genus Doropygus, with as subgenera, Doropygus and Notopterophorus. Seven species appear to be known. Organization of Trilobites.*—The veteran H. Milne-Edwards, in discussing the results of the researches of Mr. Walcott,f concludes that the alliance, on which he long ago insisted, between the 'Trilo- bites, Isopoda, and Phyllopoda, is strengthened rather than weakened by these studies; he cannot believe that they were representatives of the Arachnidan type from which the Limuli appear to have been de- rived, and he thinks that a group composed of Trilobites, Limul, and Eurypterina would be altogether artificial and inadmissible into a natural zoological classification. It is pointed out that although there is, at first sight, a very con- siderable resemblance between young Limuli and young Trilobites, yet that the latter soon become provided with thoracic segments, and, to cite characters of less importance, they tend to become ornamented with those long spiniform prolongations, the presence of which is so characteristic not only of Zoex, but of many adult Macroura. If we examine the respiratory organs of the Trilobites, we find them to differ much more from the Limuli than they do from the Branchiopoda or the Hedriophthalmata. The principal differences between the external structure of a Limulus and of a Phyllopod or an Isopod are to be found in the relations of the mouth to the appendi- cular system, and the mode of division of labour between the different parts. In the Limuli we find two distinct groups: one forms a masticatory, prehensile, and ambulatory system, at the centre of which we find the mouth; the other, the respiratory apparatus, is situated more posteriorly, and presents none of the characteristic forms of any Arthropod walking limb; no known existing animal has a similar structure, and no one of the recently observed facts leads us to see any close resemblance to them in the Trilobites. Prof. Milne- Edwards has now no doubt as to the existence of a long series of post- cephalic limbs in the Trilobites, and the characters of these appear to him to present a certain resemblance to those of Apus ; it is possible that they were almost altogether homomorphous and natatory rather than ambulatory. It is pointed out that we have an erroneous idea of the essential characters of the appendicular apparatus of the Phyllo- poda, if we imagine that they are always entirely soft and membranous ; in Apus the coxopodite and some of the succeeding joints of the internal ramus are thick and firm, and we can imagine that under the * Ann. Sci. Nat. (Zool.) xii. (1881) Art. No. 3, 33 pp. (8 pls.). + See this Journal, i. (1881) p. 736 ZOOLOGY AND BOTANY, MIOROSCOPY, ETC. 509 effects of fossilization nothing but the parts of this internal ramus might be left to be preserved. Vermes. Chemical Composition of Tubes of Onuphis.* — Professor O. Schmiedeberg finds that the tubes of this Annelid consist not only of a mixture of albuminoid substance and of potassium and sodium, but of a special body (onuphin) made up of organic and inorganic bodies ; the presence of this body may be explained by the view of Ehlers that the tube is a secretion of the separate segments of the animal, a view which is based on the plentifulness of the secretion of certain glands. The question of the origin of the chemical com- ponents is considered by a reference to the quantitative analyses of various sea-waters, and it is pointed out that the striated structure of the tube is due to the different layers being separated by an albu- minoid substance. The question of their food is not yet satisfactorily settled, nor have we yet the necessary knowledge of the exact consti- tution of onuphin. Nematoid Hematozoon from a Camel.tj—Dr. T. R. Lewis, recalling the fact that the occasional presence of nematoid organisms in the blood of various animals has long been ascertained, and that ten years ago he had shown that in India a somewhat similar condition was observable in man (associated with certain forms of grave disease), points out that an important contribution to our knowledge of the hematozoa of the lower animals has been made by Dr. G. Evans, the head of the veterinary department of Madras, who, whilst making a post-mortem examination of a camel, found that the blood of the animal swarmed with the brood of a nematoid parasite resembling the hematozoon of man, Dr. Evans found, further, that the parental form existed in the lungs, the pulmonary arteries of which were plugged by tangled masses of the thread-like parasites. They were also found in the mesentery. A comparison of these hematozoa with those found in man shows that, whereas the embryonal forms of both kinds are indistinguish- able under the Microscope, nevertheless the mature form as met with in the camel differs, both as to size and structure, from the only male and female specimen of the mature form met with in man which has hitherto been obtained in India; and so far as Dr. Lewis is aware, this hematozoon of the camel differs from any hitherto described parasite. Should further inquiry confirm the supposition that the parasite is new to science, he proposed that it should be called Filaria Evansi. A preliminary description is given of both male and female forms. Development of Marine Planaria.{— Among other important points, Prof. E.Selenka here discusses the affinities of the Planaria to the Ctenophora and the Nemertinea. We find a considerable * MT. Zool. Stat. Neapel, iii. (1882) pp. 373-92. + Proc. Asiatic Soc. Bengal, 1882, pp. 63-4. + Zool. Studien, ii. (1881) 44 pp. (7 pls.). 510 SUMMARY OF CURRENT RESEARCHES RELATING TO though not complete similarity in developmental history between the Planaria and the Ctenophora. In both cases (1) the endoderm arises as four large pale cells, and this layer gives rise to a quadri-radiate enteron, which is permanent in the Ctenophora, but modified in the Planaria. (2) The gastrula arises by epiboly, and the blastopore and permanent mouth are coincident in position. (3) Stinging cells are to be observed in both. (4) The embryo has in both a predominantly radial (symmetrical) arrangement, but in both this is later on more or less completely modified into a bilateral sym- metry. On the other hand—(1) There does not seem to be in the Planaria more than a feeble indication of an aboral sensory capsule with otoliths, such as seen in the Ctenophora. (2) A complete in- vestment of cilia is but rarely found in the Ctenophora, e.g. embryo of Eucharis. (3) Nothing comparable to the eight ctenophoral plates of the Ctenophora can be detected in the Planaria. The relations of the Ctenophora and the Planaria are hardly to be doubted. Turning to the Nemertinea, we find that in these the quadri- radiate symmetrical cleavage is confined to the very earliest stages, the endodermal cells are small, and there is no kind of communi- cation between the enteron and the celom; on the other hand, stinging organs are to be found on the proboscis, the blastopore and permanent mouth are coincident, and, in fine, the Planaria in some cases present intermediate conditions between the Nemertinea and the Ctenophora. The chief objects of the author’s investigations have been Lepto- plana tremellaris, L. alcinoi, Eurylepta cristata, and Thysanozoon diesingi. Eyes of Planarians.*—Former investigations { having done little more than elucidate the ewternal characters of these organs, J. Carriére hag applied himself to determining their intimate structure, especially that of the nervous elements. The method employed was preserva- tion by Lang’s method, viz. a liquid composed of chloride of mercury 5 parts, glacial acetic acid 5 parts, water 100 parts; after twenty minutes or half an hour the specimen was transferred to alcohol of 70 per cent.; sectious were made and stained with picrocarmine. In Planaria polychroa there is an optic ganglion immediately in con- tact with each eye, on its outer side, and consisting of an external layer of nuclei resembling those of the cerebral ganglion, and about -008 mm. in length, enclosing a larger mass of fine fibres. Among these fibres are some which are strongly refractive, and pass in straight lines inwards, swelling ‘out, and ending in rather broad knobs within the pigmented hollow (“ pigment-cup’’), and which they probably fully occupy in life. The pigment mass consists of small globules, varying in size from +255 to e457 mm. in diameter. The eye of Dendrocelum lacteum is double; the pigment-cup is single, but has two posterior openings instead of one. The eye of Leptoplana tremellaris, described by Keferstein in very different terms, appears, however, to agree - * Arch. Mikr. Anat., xx. (1881) pp. 160-74 (1 pl.). + See this Journal, i. (1881) p. 605. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 511 essentially with those just described. Study of pathological and abnormal specimens appears to show that the large eyes of the two former Planarians have been developed from aggregations of small ones, each consisting of a nervous cell invested by pigment; such eyes, in fact, appear in some cases as accessory appendages to the main organs. Polycelis nigra has the margin of the anterior end of the body beset with pigmented ocular organs, which are often united together in twos or threes. Their structure differs, however, very widely from that of the eyes of Planaria polychroa. Each eye consists of a homogeneous sphere, invested on its posterior side with a pigment- cup of distinct granules, which is open in front; in contact with the back of the latter organ is a large trausparent hemispherical nucleated cell. The eye appears to be surrounded by ganglion-cells whose nuclei are distinct, but whose exact relations to the eye have not been made out. Development of the Orthonectida.*—C. Julin, although agreeing with Metschnikoff in regarding Rhopalura ophiocome and Intoshia gigas as the male and female forms of the same species, has never been able to detect them both in the same Ophiurid. When an Amphiura squamata infested with males is opened there escape hundreds of individuals in different stages of development. After the first cleavage one of the blastomeres is very much larger than the other, and is more opaque; this is the ectodermic while the other is the endodermic globule. The former gives rise to as many as fourteen cells before the latter divides at all; thus there arises a condition of epiboly, where the endodermic cell is ovoid in form and has its long axis parallel to that of the embryo; the enclosed cell now undergoes division, and gives rise to a small cell at either end; one of these occupies the orifice of the blastopore. These small cells now divide into six and four respectively, and the ectoderm becomes completely ciliated; as the embryo elongates the small cells increase in length, and becoming fusiform completely envelope the central endodermal mass; in the adult they form the longitudinally striated fibres. Meantime, the central endodermic cell has divided into a large number of smaller cells, each of which contains a fragment of the primitive endodermal nucleus; each of these gives rise to a sper- matozoon. Although the primordial muscular cells have been given off from it, the central cell still possesses a true membrane, which persists during the whole life of the animal and forms a pouch for the contained spermatozoa. While the males are free the embryonic females are connected together by a granular mass (the sporocysts of Giard, plasmodial tubes of Metschnikoff). There would appear to be very great difficulties in the study of their earlier stages owing to this mode of connection. But here also there is ectodermic epiboly, though the endodermic cell divides earlier to give rise to a mass of polyhedral cells, sur- rounded by a layer of cubical non-ciliated cells. Later on these peripheral cells become cylindrical, and still later they form a com- * Bull. Sci. Dép. Nord, iv. (1881) pp. 309-18. 51D SUMMARY OF CURRENT RESEARCHES RELATING TO plete but very delicate layer of fibrils, apparently comparable to the muscular layer found in the corresponding position in the male. The central polyhedral cells give rise to ova. There is, therefore, an essential agreement between the developmental processes of the male and female. The male products escape, by the rupturing of their investing wall, into the muscular layer, where a passage is found for them ; the ectoderm undergoes change and atrophy, and the spermatozoa make their way out. The ectoderm of the female breaks off at a non- ciliated region at the anterior end, and thus the ova escape. There is another female form which seems to divide into two or three pieces, and which is distinguished by being flattened, and not cylindrical. The females, when mature, appear to leave one host to swim in the water and to enter another, and there is some reason to believe that the cylindrical forms give rise to the males, while the flattened forms would seem to be the parents of the females. These latter possibly arise by parthenogenesis. The author promises a fuller paper, in which he will give more details and full reasons for his belief that the Orthonectida belong to Van Beneden’s group of the Mesozoa, and he concludes with an ob- jection to the application of the terms metamere or segment to these creatures, as the segmentation is superficial, affecting only the ecto- derm, and the number of segments does, it is allowed, vary. Eyes of Rotifers.—Referring to his note read at the June meeting of the Society,* Mr. Badcock writes (July 17) :—“ Yesterday for the first time I discovered eyes in a group of adult Floscularia cornuta, and saw them again very distinctly in Stephanoceros eichhornii. It seems to me desirable to put on record the fact that the eyes are found in the adult forms of Melicerta ringens, M. tyro or tubicularia, Floscularia cornuta, and Stephanoceros eichhornii, in all of which the eye is ignored in the usual descriptions and drawings. ‘The eyes are not readily seen, but I have had some very fine specimens, and may be able eventually to demonstrate their existence in all the forms in which they were supposed to have been lost.” Echinodermata. Anatomy of Holothurians.j—E. Jourdan finds in the connective tissue of the integument of these Echinodermata elements forming a plexus; they are coloured grey by osmic acid, are rarely isolated, and are very often united into bundles. They arise from nerves which penetrate into and extend through the skin. The fibres of this nervous plexus are accompanied by nuclei, which are chiefly found at the points of interlacement of the fibres. These fibres are very fine, slightly varicose, and accompanied by fatty granu- lations. ‘The nervous centres consist of fibres and cells. The latter are frequently, though not always, unipolar. The muscular elements of Holothurians are made up of fibres * See this Journal, post, Proceedings. + Comptes Rendus, xciv. (1882) pp. 1206-8. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 513 which are remarkable for the irregularity of their form and their length. They are always provided with one or more nuclei, which are always lateral in position, large in size, and attached to the fibre by a delicate sarcolemma. The walls of the Polian vesicles consist of an outer layer of flattened cells, which recall the endothelial lym- phatic cell; a layer of connective tissue in which the fibres are longi- tudinal ; a layer of circular muscular fibres, which are very long, and have the appearance, when extended, of elastic fibres, in a state of contraction. They present a number of swellings. Within this there is a layer of epithelial cells. Hybridization of Echinoidea.*—R. Koehler finds that, at Mar- seilles, the genital glands of most species are mature in March or April. In making experiments, however, it is necessary to assure oneself by microscopical examination that the elements are ripe, and with the crossing experiments it is right to fecundate by their own spermatozoa the ova of the species treated. When the ova of Strongylocentrotus lividus were fecundated by Spherechinus granu- laris, the Pluteus was regularly and perfectly developed. The same happened when the male was Psammechinus pulchellus. When the male was Dorocidaris papillata, the eggs did not pass beyond the blastula-stage, but the spermatozoa used were here somewhat inactive. A female Strongylocentrotus is not always fecundated by a male Spatangus purpureus. Sometimes, however, even the gastrula-stage may be reached. Other examples are given, and the whole shows that cross fecundation is possible, within very wide limits, among the species of the Echinoidea; while the Pluteus derived from the crossing of two regular Echinoids may not differ much from the normal Pluteus of the female in the experiment, there are certainly well-marked differences between the legitimate Pluteus of a Spatangus and the hybrid Pluteus of that and Psammechinus. While the ova of one species may be fertilized by another, the reverse may not hold true. Variation in Asterias glacialis.|—Professor Jeffrey Bell describes “ six sets at least” of forms of this species. In the simplest there is never, in addition to the median row of spines along the back of each ray, anything more than a single isolated rather small spine on either side. Passing through forms in which there may be a few of these intermediate spines, or a larger number, we get to those in which there is a distinct row on either side of the now less conspicuous median one: two rows may be indicated on either side, or may be conspicuously developed. AIl the forms selected came from the coasts of Portugal, the Azores, or Madeira. It is pointed out that the character and arrangement of the pedicellarie depends on the distri- bution of the spines, and it is, in conclusion, suggested that in the history of the Asteroidea the next point to work out “is the nature * Comptes Rendus, xciv. (1882) pp. 1203-5. t Zool, Anzeig., v. (1882) pp. 282-4. Ser. 2.—Vot. II. 2M 514 SUMMARY OF CURRENT RESEARCHES RELATING TO of the sea bottom, of the surroundings, of the food, and of their enemies, as determining the strength, size, and disposition of the abactinal spines.” Ccelenterata. Development of Calcareous Skeleton of Asteroides.*—G. v. Koch having observed that between the crystalline calcareous substance which forms the septa of Mussa and the hyaline connective substance that surrounds it, there are cells which form a continuous layer, asked himself whether these cells secrete the calcareous skeleton, and do they belong to the connective substance (mesoderm), or are they ectodermal in origin, and, therefore, a secretion from the primitively external surface, which is only apparently internal ? To resolve these questions he has studied the development of the skeleton in Asteroides, where he finds that the first indications are only to be observed some time after the larva has become fixed. These appear as a circular disk with a cavity in the centre, consist chiefly of carbonate of lime, and are composed of spheroidal pieces, made up of concentrically arranged layers. The spheroids are larger in the centre, and decrease in size as they approach the margin of the disk. This earliest skeletal rudiment lies between the lower layer and the ectoderm of its aboral surface. The cells of the latter, like those of all other parts of the surface of the body, are cylindrical, and no calcareous concretions are to be observed within them. From these facts the author concludes that the first rudiment of the skeleton is neither a product of the endo- derm nor of the connective substance (mesoderm), but that it is a secreted product of the ectoderm. The further development of the skeleton is brought about by the completion and enlargement of this basal disk, and by the formation of septa. The former is effected by the formation of new spheroids, by growth, and by subsequent fusion ; the septa arise from radial endodermal ridges which attain a consider- able size. Later on, the ectoderm enlarges, and there appear cal- careous secretions, formed of small crystals, which fuse with the disk, and form the first rudiments of the septa. In the next stage the septa are higher and begin to branch at their peripheral ends. Growing still more, they broaden out, partly into the form of thin lamelle, get small spinous processes, and fusing at their peripheral ends with one another form the theca. The columella is similarly formed by a fusion of the central ends. While these changes have been going on there is a further secretion of carbonate of lime at the free edge of the young Asteroides. This unites with the aboral disk, and gives rise to a thin lamella. This is the epitheca of authors, and it is important to note that at first it is completely separate from the theca, and that it only secondarily becomes connected with it. Very little now remains to be observed, except the growth of the septa, theca, columella, and epitheca. We may remark, however, that from the primitively twelve septa there soon arise six which are stronger than the rest, and, alter- nating with them, appear to give rise to two cycles; twelve new septa * MT, Zool. Stat. Neapel, iii. (1882) pp. 284-92 (2 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 515 also begin to appear. Still later on, it may be seen that the septa form three or four cycles, which consist respectively of 12, 12, 24, and 48 pieces; the younger always appear between two older ones. Development of Aquorea.*—Prof. C. Claus states that Aquorea forskalea deposits its ova in March. They are without an investing membrane, and are deposited in great quantities. The directive cor- puscle is soon expelled, and just below the point at which it escaped a clear vesicle may be seen in the yolk for a few hours afterwards. The central cleavage-cavity is open at both ends until the 16-sphere stage. Later on, when these become closed, the region of the upper pole may be still distinguished by the greater thinuess of the walls of the hollow sphere at that point. As the cells become smaller, cilia appear on the surface, and the mass begins to rotate. It soon, how- ever, elongates, and becomes narrower near the lower pole, which is now posterior. The cells of this region become much higher, and gradually form a projecting process into the cleavage-cavity. Some of the more internal cells break away, and form isolated spheres within that space. This process goes on until the whole becomes filled with small cells, which represent the endoderm. At first there is distinct continuity between the endodermal cells, and the ectodermal from which they have arisen. On the third day the embryo presents all the characters of a Planula, and swims freely about. Stinging cells appear, and the long axis of the body is marked by a somewhat irre- gular line, which is the optical expression of a cleft in the endoderm, On the fourth and fifth days this cleft becomes wider and filled with dark granules. In this condition the larva swims about freely for some time. Fixation has not been directly observed. This polar ingrowth of the endodermal cells is not any kind of delamination, but has, as the author hopes to show in a further communication, a not distant connection with the other mode of development, which is known as that of invagination. Porifera. Hybridization in Fresh-water Sponges.j—Mr. E. Potts, in ex- hibiting some fragments of fresh-water sponges collected in the Boston Aqueduct, consisting of, it is believed, Spongilla paupercula and a new species, Meyenia acuminata (with others), points out the following exceptional features as marking the collection: (1) that all the statospheres, whether belonging to Spongilla or Meyenia, were smooth, that is, without a granular or cellular “crust”; (2) the apparent absence of dermal spicules in both, and the abnormal character of these belonging to the statospheres. The appearance is not infrequent, but has, so far as known, heretofore been limited to the genus Spongilla. The recurrence of the same feature in the associated genus Meyenia, coupled with the fact that many of the birotulates upon its statospheres were imperfect, the rays being more * Zool. Anzeig., v. (1882) pp. 284-7. t Proc. Acad, Nat. Sci. Philad., 1882, pp. 69-70. 2m 2 516 SUMMARY OF CURRENT RESEARCHES RELATING TO or less aborted approximating their shape to that of the spined fusiform acerates of Spongilla, gave rise to the suggestion that here, possibly, had been, not merely a mechanical mixture by inter- or super-position of species, but an organic hybridization produced by the flowing together of the amceboid particles of which the sponges are composed, or even by a fertilization of the ova of one by the spermatozoids of the other. ; It is important to note that the specimens were collected in February, when the sarcode matter had nearly all been washed away with, probably, accompanying changes in the presence or numbers of the smaller spiculz. Boring Sponges.*—Mr. J. D. Hyatt, referring to papers in the Journal of the Quekett Microscopical Club (in which the question is discussed whether Cliona forms the burrows in which it is found or whether they are excavated by annelids or other animals), is convinced that there is one weak point characterizing all the ob- servations, which invalidated to a great extent the conclusions on both sides. This was, that dried specimens had been used, or, as one author mentions, the live sponge occupying old shells and rocks. It occurred to him that a study of the live sponge occupying the shells ~ of healthy, living molluscs, might present evidence for one side or the other that had hitherto been overlooked, and he therefore procured some oysters, a considerable number of which had shells tenanted by Cliona. An exhaustive microscopical examination of these and similar specimens, seems to him to establish, beyond a possibility of doubt, that the sponge is, in this case at least, the only factor to be held accountable for the burrows. The outer layer of the shells was punctured with numerous holes, often many hundred, varying from the <5 to the z35 of an inch in diameter, generally occupied by the oscule of the sponge. Between the outer and inner layers, and extending laterally, the shell was almost entirely excavated, and the space occupied by the sponge and its numerous spicules; while extending inward from this sponge-mass were innumerable minute, branching and ramifying burrows, uniformly and completely filled with corresponding arms of sponge, many of which extend quite through the interior layer of shell. The contact of these arms with the external membrane of the oyster causes the latter to deposit at such points an additional amount of lime carbonate, and the interior surface of such shells presents the appearance of numerous little prominences caused thereby. The only possible theory that will account for these burrows, if they are not made by the sponge, is that they are the deserted ex- cavations of worms; but this theory is untenable, as it would be necessary to suppose that the shell was once inhabited by an innumer- able multitude of such worms; otherwise the perforations through the inner cell would have been closed, and all of these must have retreated at the same time, so completely that no trace of them could * Amer, Mon. Mier. Journ., iii. (1882) pp. 81-4 (8 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 517 be found, and the sponge must then have extended its growth into the deserted channels with such rapidity as to fill every minute branch before the oyster could bar it out by the secretion of enough new shell to stop apertures z0'55 inch diameter. But this is not all. The burrows occupied by Cliona branch in all directions and diminish in diameter as they extend inward, which would represent a method of boring quite inconsistent with the habits of any known borer. Again, in these specimens, the sponge was found in small spots on the thin lamine, around the sides and anterior edges of the shell which represent its most recent external growth, and in such cases the lamine were perforated from side to side. Protozoa. De Lanessan’s Protozoa.*—This will be found a welcome book by microscopists, as it is copiously illustrated with woodcuts and deals with the subject in a very readable form, while yet being far beyond a merely popular handbook. The author’s leading divisions are Monerans, Ameebans, Forami- nifera, Radiolaria, Infusoria (flagellate, ciliate, and tentaculate), and he claims to have originated a new plan for such a book differing from that of ordinary treatises. He commences in each case with con- sidering in its adult state an individual species chosen as the best type of the group (by its being readily procured, best known, &c.), dealing with all the details of its organization, with its physiological functions, its habits, and the development of its organs, considerable importance being given to embryology. He then describes the other leading forms of the group, and when all these have been disposed of a separate chapter sums up the common characters of the group, its relations with neighbouring groups, and its classificatory divisions. The author considers that a great mistake is made when the converse course is adopted and the characters of the group are dealt with, noticing the peculiarities of the organization of the different types of the group in the course of the general description. By this method, he says, “a Mollusc becomes a kind of abstract entity clothed with characters rendered so vague by the generalization that the student has the greatest difficulty in discovering them in. the specimen given him to dissect.” Taking the Amcebans for an example the following is the author’s arrangement :— 1. The principal forms. (a) Gymno-Ameebans. Under this head are described A. princeps, A. coli, Podophrys elegans, Pelomyxa palustris, Dactylospherium radio- sum, D. polypodium, D. vitreum, Hyalodiscus rubicundus, Petalopus diffluens, Plakopus ruber, Podostoma filigerum, and Mastigameba aspera 9 figs.). (b) DU eee sait “Pactedoabinigs patella, Cochliopodium pel- lucidum, Difflugia oblonga, Quadrula symmetrica, Arcella vulgaris, and Amphizonella violacea (6 figs.). * J. L. De Lanessan, ‘Traité de Zoologie. Protozoaires,’ vii. and 336 pp. (281 figs.) 8vo, Paris, 1882. 518 SUMMARY OF CURRENT RESEARCHES RELATING TO 2. Common characters, classification, and affinity. The author defines Amcebans as Monerans which have acquired a nucleus and contractile vacuoles, and distinguishes 17 genera, a third group of flagellate Amcebans being here formed of the gencra Mastigameba, Reptomonas, and Rhizomonas. Kent’s Manual of the Infusoria—This is now completed by the issue of the 6th part and forms a magnificent monograph of the Infusoria which cannot fail to be of the greatest value and assistance to the microscopist. The concluding part has an appendix containing a notice of species recorded during the publication of the work, a glossary of technical terms, an extensive bibliography of the Infusoria, and a plate illustrating the apparatus employed by Messrs. Dallinger and Drysdale and by Professor Tyndall in their investigations on Monads, &e. The plate also contains a figure of a Microscope and lamp arranged for working with high powers, the Microscope being horizontal and the lamp turned with the narrow edge of the flame towards the condenser. The plan described is by no means the novelty which it is suggested to be; it is, in fact, the one adopted - since the days of Quekett for all delicate high-power work. Flagellata.*—In a previous communication J. Kunstler} recorded the results of researches undertaken on the Flagellata, to which more recent observations enable him to add some new facts. Cryptomonas ovata Ehrbg., after being submitted to the action of acetic acid, appears to be covered with filaments; Biitschli, who has described analogous productions in Chilomonas paramecium Ehrbg., considers that they are trichocysts, that is, organs of defence com- parable to the nematocysts of Coelenterata; the author, however, has never been able to see in this organism the small rods which are so abundant in the integuments of certain ciliated Infusoria, and within which, if the comparison with urticating organs is correct, the attenuated prolongations should at first be enclosed. The filaments, incomparably more numerous than those which have been figured by Biitschli, form a thick peripheral layer, and their length is often enormous, thus there are some ten times the length of the body; generally they take an upward inclination. At the upper part of the body, on the prolongation of the posterior margin of the hollow in the digestive chamber, two or sometimes three of these prolongations may be observed which are thicker, longer, and more rigid, whilst the others are often slightly flexible. Cryptomonas erosa also has these filaments. In the cold season, Cryptomonas ovata acquires special characters. The nucleus only contains the large nucleolus. The cuticle is generally very thick over the whole surface of the body, and the vacuoles in it are very easily visible without the intervention of any reagent ; in certain points this cuticle presents a very considerable development, for example at the lower extremity where it forms a * Comptes Rendus, xciv. (1882) pp. 1432-3. + Ibid., xciii. (1881) pp. 746-8. See this Journal, ante, pp. 62-3, ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 519 prolongation directed backwards, or better at the dorsal rostrum (which is itself prolonged) where it often forms a long point. It also presents, besides the line devoid of green colouring matter, the existence of which on the left face the author has already recorded, another, colourless, tolerably broad, longitudinal line through the whole length of the right face. Finally the starch-grains of the deep mamillated layer are rarer and very thin; but extending over almost every part of their body are seen some irregular more refringent corpuscles resembling concretions, which are perhaps also formed of starch, although they do not turn blue under the influence of iodine. In an infusion that was in an advanced state of decomposition the author has met with Chilomonas paramecium Ehrb. in a sort of palmelloid state; a number of individuals of this species being united in a common transparent gelatinous mass, having a great resemblance to a Zooglea. Cienkowski has observed an analogous phenomenon in Cryptomonas polymorpha, and was confident that it was a mode of reproduction. The author has never observed this phenomenon except in cultures which were more or less putrefied and placed in unfavourable conditions with regard to light; these organisms are always isolated and very active in clear water well exposed to the light. Astasia costata has a muscular, subcuticular layer with spiral fibrille analogous to those in the Euglene. The contractile vesicle of Phacus pleuronectes Duj. has distinctive vacuolar walls resembling those of the analogous organ in Cryptomonas. The terminal flagellum of Monas vinosa Ehrbg. that Cohn considers to be merely the mobile spore of Clathrocystis roseopersicina (a chromogenous bacterium), displays a transverse striation when it has been submitted to the action of reagents that colour strongly. Cell-parasite of Frog’s Blood and Spleen (Drepanidium ranarum),*—-In 1880 we referred f to a discovery made by Dr. J. Gaule of certain Wiirmchen or “vermicles” in frog’s blood, which he considered to be simply protoplasmic portions of the corpuscles separated for a short independent life, and not parasitic organisms. Prof. Ray Lankester now points out that these are, in fact, the minute, sausage-like parasites, discovered by him in 1871 (for which he proposes the name of Drepanidium ranarum), and that they are clearly parasitic organisms, probably the young stage of a sporozoon allied to Sarcocystis or to Coccidium. Some of the chief observations of Dr. Gaule are, in fact, directly favourable to the view that the Wiirmchen are independent parasitic organisms, for (1) they exhibit active movements under circumstances usually favourable to the movements of the Protozoa and Protophyta ; (2) they occur within the cells of the organism in which they are found as well as in its fluids; (3) they are present in some frogs and not in others living under approximately the same conditions ; (4) they vary in abundance in the same frog, examined at different times ; * Quart. Journ. Micr. Sci., xxii. (1882) pp. 53-65 (5 figs.). ¢ This Journal, iii. (1880) p. 232. 520 SUMMARY OF CURRENT RESEARCHES RELATING TO (5) they are abundant in one time of the year and not at another; (6) they are seen on the stage of the Microscope to penetrate and enter cells by means of their active movement ; (7) they are also seen to escape from cells by the same activity; (8) they are localized chiefly in the spleen though not confined to that organ ; and (9) though most abundantly observed in certain specimens of Rana esculenta at Leipzig, yet they have also been observed in Rana temporaria and in Triton sp. : These observations are not merely consistent with the view that Drepanidium is an independent parasitic organism, but are directly in favour of that view, since they are readily explained if that view be admitted, whilst they remain as isolated and unconnected facts, each requiring a special assumption for its connection with any other theory which may be advanced as to their nature, when the obvious one that they are parasitic organisms is rejected. The only fact which Dr. Gaule adduces which is inconsistent with the parasitic nature of Drepanidium is that in some cells, especially blood-corpuscles, these bodies are not present when an examination of them is first made on the field of the Microscope, and that on the addition to the preparation of 0:3 per cent. solution of sodium chloride the Wiirmchen are formed there and then in the cells. Prof. Lankester, however, doubts altogether the accuracy of Dr. Gaule’s statements on this point, the supposed fact being really an erroneous interpretation of an observation. Just as the nucleus in the frog’s red corpuscle is frequently not visible during life and only becomes visible as the result of the first change in blood removed from the blood-vessels, so Drepanidium is invisible in the normal condition of the red blood-corpuscle owing to the identity of the refractive index of its delicate substance and that of the body of the corpuscle. It only becomes visible when a change in the refractive indices takes place. Prof. Lankester suggests that researches should be directed to the discovery of a Gregariniform stage, and of cysts containing spores, or of isolated spores in which several Drepanidia may be enclosed. These phases in its life-history are very possibly to be met with in other regions of the frog’s body than the blood-vessels or the spleen. Development of Trypanosoma.*—Dr. J. Gaule has also re- investigated the remarkable organism of Flagellate character found in frogs’ blood, the so-called Trypanosoma sanguinis Gruby, and puts forward a decidedly new and original interpretation of it, arriving at the conclusion that it is not an independent organism, but is produced by spontaneous modification of the white blood-corpuscles. Its pro- duction is favoured in general by warmth, hence it is found in frogs more particularly at the commencement of the warm period of the year, and it may also be seen to occur during the winter in frogs which have been kept in a warm room. These conclusions are attempted to be supported by the fact that the direct and frequent * Arch. Anat. u. Physiol., 1880 (Physiol. Abth.) pp. 375-92 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 521 conversion of white blood-corpuscles into Trypanosoma (or Kymato- cytes as Gaule proposes to call them) may be observed on the warm stage. The transmutation of the white corpuscles is said to take place as follows :— At one point in the periphery of the corpuscle is developed a vibrating flagellum from which is subsequently but gradually pro- duced a hyaline undulating ribbon; ultimately the whole body becomes flattened out and the flagellum degenerates into a pointed process of the lobate mass thus formed. The fully developed kymatocytes show such exuberant multiplicity of forms that the writer is able to distinguish no fewer than five types among them. Conversely, however, the Trypanosoma have the power of being re-converted into leucocytes with amceboid movements. Gaule, according to his showing, has directly observed the process of re- conversion, which he describes, many times, and he elucidates it by pictorial representations of the successive stages. One circumstance which appears to be of special importance in the matter is not made clear in the memoir, namely that as the white blood-corpuscles of the frog are known to be provided with a number of small nuclei, the Trypanosoma ought also to exhibit them, but neither are they described or do any cell-nuclei appear in the figures. This point seems to Prof. O. Biitschli* the more important, because in the life-history of certain Protozoa (cf. especially Ciliophrys Cienk.), amceboid and flagellate stages succeed one another, so that a similar alternation in the life-history of Trypanosoma proves nothing of itself as against their Protozoan nature. Indeed, the very point whether these amceboid bodies whose transmutation gives rise to the Trypa- nosoma, really are white blood-corpuscles, appears to Prof. Biitschli to be by no means free from uncertainty notwithstanding the present investigations. Prof. Lankester also considers + Dr. Gaule’s views to be “ devoid of justification.” New Gregarines.{—Dr. R. Réssler found in the enteric canal (chiefly the ceca) of the Phalangida, among other parasites, two Gregarines which appeared to be new. Actinocephalus fissidens n. sp. has twelve pairs of cleft hooks on its head, and between each pair there is a simple spiniform process. Stylorhynchus caudatus has the “head” placed on a stalk, and provided with twelve ridges or projections, which extend beyond the margin of the head and then divide. This form is also provided with a delicate caudiform ap- pendage, which is not separated from the body proper by any septum. In some cases these parasites were so numerous that the death of the host may be ascribed to their presence. * Zool. Jahresber. Neapel, i. (1880) p. 165-6. t+ Quart. Journ. Micr. Sci., xxii. (1882) p. 65. } Zeitschr. f. wiss. Zool., xxxvi. (1882) p. 700 (2 figs.). 522 SUMMARY OF CURRENT RESEARCHES RELATING TO BOTANY. A. GENERAL, including Embryology and Histology of the Phanerogamia. Chemical Difference between Dead and Living Protoplasm.—Dr. O. Loew sends us a photograph illustrating his researches on this subject,* from which Fig. 90 is copied. The upper part of the woodcut shows a filament of Spirogyra nitida Ktz., killed by a 0°1 per cent. solution of citrie acid before Fig. 90. treatment with the silver reagent, no blackening being produced, and the spiral arrangement of the chlorophyll-bands being distinct. The lower part shows a filament when placed in the living condition into the silver reagent, the reducing effect of the living protoplasm on the silver-salt having converted the cell-contents into a black opaque mass. Killing of Protoplasm by Various Reagents.t—Loew and Bokorny have applied their test for distinguishing between dead and living protoplasm, viz. its power of reducing dilute alkaline silver solutions, to determine the degree of resistance offered by protoplasm to various destructive agents. After complete withdrawal of light for five days, about 50 per cent. of the filaments of several species of Spirogyra still showed signs of life ; it was not till the sixteenth day that all were completely killed. ‘Twelve hours’ desiccation over con- centrated sulphuric acid destroyed the appearance of life in almost every cell. Triturating in a mortar destroyed life, even where there was no apparent injury. After warming in water of 46° C. for a short time, about 10 per cent. of the cells still showed signs of life, at 55° about 2 per cent.; and a temperature of 60° altogether destroyed life. Exposure of one hour to vapour of ether destroyed life except in some cells containing a large amount of oil and in spores, sugar being formed during the process. After twelve hours in chloroform- water, 5 per cent. of the cells were alive; two days in petroleum * See this Journal, i. (1881) p. 906; ante, p. 67, 361, and 440. } Pfliiger’s Arch. f. d. gesammt. Physiol., xxvi. (1881) pp. 50-9. See Bot. Centralbl., ix. (1882) p. 392. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 523 destroyed all power of reaction, causing copious formation of sugar ; absolute alcohol destroys life in an extremely short time. Exposure for twenty-four hours to a stream of carbonic acid destroys the life of the cells. Hydrochloric acid and citric acid produce an injurious effect almost immediately. The power of resistance to alkalies is much greater. Immersion for one hour in a 10 per cent. solution of sodium chloride destroys most of the cells. Metallic poisons act more slowly ; some cells still show signs of life after immersion for two hours in 1 per cent. solution of sugar of lead, or for twelve hours in 0-1 per cent. of arsenic acid, or for twelve hours in 1 per cent. of zine vitriol. Of organic poisons, gallic acid, pyrogallol, resorcin, hydrochinon, in 1 per cent. solutions, act rapidly, destroying life in a few hours, as also 0°2 per cent. salicylic acid, and 1 per cent. carbolic acid in one hour. Alkaloids, acetate of strychnin, chinin, and very dilute veratrin do not prevent the reaction, although the structure of the protoplasm is destroyed; 1 per cent. sulphuric acid destroys the power of reaction. Apical Cell-growth in Phanerogams.*—In order to determine the much-disputed cause of the want of a special apical cell in flowering plants, G. Haberlandt has closely investigated the process of apical cell-growth in the following instances: the cell-divisions of the cortical parenchyma in the laburnum and in the trichomes of the leaf-stalk of Begonia Rew ; the formation of the stomatal apparatus and neighbouring cells in Mercurialis and in Crassulacee ; the cell- divisions in the formation of the hypodermal bast-cambium bundle in the leaves of Typha latifolia ; the formation of the midrib of the leaf of Elodea canadensis ; and the formation of the leaves and axillary shoots of Ceratophyllum demersum. The general conclusions arrived at are, that in Phanerogams there are tissues and masses of cells of very different extent and significa- tion, which have been formed by apical cell-growth. It may be either rows of cells only that increase by apical growth, as in the first and second of the above instances, or plates of cells, as in the third, or finally masses of cells may exhibit apical cell-growth, as in the two last. Each of the three tissue-systems of Hanstein, der- matogen, periblem, and plerome, grows at first by means of a single apical cell. Development of Bordered Pits.t—E. Russow has carefully in- vestigated the development of bordered pits, and of the membrane of wood-cells, more particularly in the Abietinew. The general con- clusions at which he has arrived are the same as those of Sanio. The growth of the wall of the border points to the interpretation of a kind of secondary division-wall, as if a free membrane were excreted on the upper side of the protoplasm. * Haberlandt, G., ‘Ueber Scheitelzellwachsthum bei den Phanerogamen,’ 29 pp. (2 pls.). Graz, 1881. + SB. Dorpater Naturforsch.-Ges. Sept. 24, 1881. See Bot. Ztg., xl. (1882) p. 182. 524 SUMMARY OF CURRENT RESEARCHES RELATING TO Development of Tissue as a Characteristic of Groups of Plants.*— M. Westermaier thus sums up his conclusions on this subject. The results of anatomical investigations in reference to affinity differ accord-: ing as the physiological idea of the subject is taken into account or not. In the latter case the result is either faise or uncertain, while the former leads to a comparison on a rational basis. This last method of inquiry results in the conclusion that in the Primulacez the presence of a ring of bast may be regarded as an anatomical family character. In Campanula, while one group has in the stem the ordinary ring of vascular bundles with the phloem on the outer, the xylem on the inner side, a second group of the genus has a phloem- bundle in the pith, with or without xylem, a difference connected with physiological functions. Stomata of Polycolymna Stuarti.,—The more or less complete fusion of two or even of three stomata into one, has frequently been noticed as an exceptional phenomenon. In Polycolymna Stuarti (Composite) F. Hildebrand states that it is so common, both on the stem and on the leaves, that it may be regarded as a normal occur- rence. The relative position of the two clefts in these double stomata varies greatly. In some cases they are parallel, in others at right angles to one another, while sometimes again one is behind the other, so that only one pore belongs to the two clefts. ‘The mode in which the guard-cells are formed out of the ordinary cells of the epidermis appears also to be subject to great variation. The author was un- able to determine whether the cells strongly charged with protoplasm divide directly into guard-cells, or whether this is only effected after repeated division ; both processes appeared to take place. The direction of the septum in consequence of which the guard-cells are formed, is also very various; it is sometimes vertical, sometimes parallel to the wall by which the mother-cell of an epidermal cell is cut off. The occurrence of double, and occasionally of treble stomata, may be attributed to these numerous variations in the mode of their formation. The stomata of Polycolymna Stuarti present also other peculiarities. The guard-cells are placed-in various positions as to height in relation to the surrounding epidermal cells. Usually the outer walls’ of the guard-cells are about at an equal height with those of the sur- rounding cells, and this is almost invariably the case with double and treble stomata. But among these are others, distributed irregularly, the guard-cells of which are more or less elevated above the sur- rounding epidermis, this variation being possibly connected with their special function. The number of stomata is about the same on the under and upper surfaces of the leaves; on the under surface they are protected by densely crowded glandular hairs, on the upper side by a dense felt of silky hairs. The stomata with most elevated guard-cells are found * MB. K. Akad. Wiss. Berlin, 1881, pp. 1050-70 (1 pl.). + Bot. Centralbl., ix. (1882) pp. 356-61 (1 pl.) ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 523 on the under surface. They are also very numerous on the upper part of the stem, where they are also protected by glandular hairs. Properties and Mode of Formation of Duramen.*—J. Gauners- dorfer gives an historical réswmé of what is known respecting the duramen, which is distinguished by frequently containing gummy and resinous substances in its vessels or cells, as well as large deposits of carbonate of lime. His own observations he sums up as follows :— The production of duramen takes place in consequence of the elements of the wood becoming filled by derivatives of the solid woody substance; these products being formed to some extent in the part which becomes indurated, and partly in neighbouring portions of the wood; by this means the extent of duramen is increased. These substances must originally be fluid and rich in tannin; but the cells contain also other substances which give to the duramen its great power of resistance. Nitric acid or ‘“ macerating fluid,” and then potash- or soda-ley, remove most of these substances, except in the case of Diospyros. If the induration is carried on suffi- ciently long, the cell-walls are also partially destroyed, and the pro- ducts of decomposition mingled with the contents. The composition of the substances contained in the duramen varies with the species; that of the Amygdalez, for example, contains gum (?), of the conifers resin, of Syringa resinous substances. The purpose of the duramen, at least in the lower parts of the branches, is to furnish a protection for the sound wood against the influence of atmospheric agents. History of Assimilation and of the Functions of Chlorophyll.t— A. Hansen gives a list of the researches and conclusions on this subject from the days of Ingenhousz, Senebier, and Hales. The first scientific explanation of the phenomena he considers to be that of Sachs, between the years 1862 and 1865, that the starch in the chlorophyll-grains is a product of the living chlorophyll, and is pro- duced in the chlorophyll by its power of assimilation. The author criticizes unfavourably the views of Pringsheim with regard to the nature, mode of formation, and functions of hypochlorin. Theoretical View of the Process of Assimilation. — In his investigations on the chemical constitution of protoplasm,§ J. Reinke was led to frame a hypothesis as to the immediate products of the reduction of carbonic acid. He points out that this gas, CO,H,, may be subjected to three degrees of deoxidation. By the removal of one combining proportion of oxygen it becomes formic acid, CO,H,, which he states is always formed in every vegetable cell. The second stage of deoxidation reduces it to formic aldehyde, COH,, a remarkably + Hansen, A., ‘Geschichte der Assimilation u. Chlorophyllfunction,’ 90 pp. Leipzig, 1882. Also Arbeit Bot. Inst. Wiirzburg, ii. (1882) pp. 537-626, { Bot. Ztg., xl. (1882) pp. 289-97, 305-14. § See this Journal, ante, pp. 361-2. 526 SUMMARY OF CURRENT RESEARCHES RELATING TO polymeric substance, two of its isomers being oxymethylen, C,H,O3, and glucose, C,H,,0,. The result of complete deoxidation is the production of methylene, CH,, a substance which cannot itself exist independently, but which again has a very large number of isomeric hydrocarbons, as diamylene, C,,H,), triamylene, C,;H.,, and tetra- mylene, C,,H,,; the highest members of this series being solid and crystallizable. With this process of reduction is associated a process of oxidation in the chlorophyll-grains, and the resulting products are derived from the balance of these two processes. The most common stage of reduction reached is that of formic aldehyde. Reinke believes that this hypothesis is in harmony with that of Pringsheim regarding the formation of hypochlorin. A portion of the formic aldehyde is reduced to the hydrocarbon condition; and the hypochlorin results from a condensation of such groups. Passing from the reducing region of the chlorophyll-grain to the respiring portion of the cell, it is there oxidized into the volatile fatty acids. Both formic aldehyde and hypochlorin are very readily oxidizable, and require the protection of the chlorophyll to prevent their oxidation. First Products of Assimilation.* — A. Mori has performed a fresh series of experiments, chiefly on Spirogyra, which confirm his previous conclusion that the first product of assimilation in chloro- phyllaceous plants is an aldehyde, probably formic aldehyde, formed according to the following equation out of the elements of carbonic anhydride and water :—CH,O, = CH,O + O.,. Absorption of Metallic Oxides by Plants.j—Mr. F. C. Phillips says that the question how far the vital processes of plants are influ- enced by the various mineral compounds presented by the soil to their roots has long been under discussion, but further than to esta- blish the fact that the presence of certain compounds in the soil tends to increase the nutritious elements and promote the growth of particular plants, little has been done towards a complete solution of the problem. It is well known that potash tends to increase the quantity of starch, that silica strengthens the stems of the grasses, that oxide of iron is essential to the production of leaf-green, and that phosphates increase the fertility of the soil for cereals, but even as regards these constant elements of every soil, very little can be positively asserted of the precise influence of any one, in the economy of the plant. Concerning the part played by the rarer elements, cesium, rubi- dium, copper, nickel, manganese, zinc, and barium, in the assimilation of carbon, nitrogen, and the functions of nutrition, and whether they are beneficial or injurious, nothing whatever is known, although modern refinements in chemical methods have led to their frequent detection both in soil and in plants. That so important a problem * Nuoy. Giorn. Bot. Ital., xiv. (1882) pp. 147-55. Cf, this Journal, ante, p. 361. ¢ Journ. Franklin Institute, exiy. (1882) po. 41-9. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 527 should have remained almost wholly unsolved must be attributed chiefly to the very great difficulties which are met in any experimental investigation, but also to the fact that the few investigations published have been carried out, in most cases, for the purpose of proving that vegetation had been injured by metallic compounds traceable to metallurgical works, and with the special purpose of founding a claim for damages, rather than to solve a scientific problem. The study of the influence of metallic compounds on plants has recently acquired great practical importance, from the fact that many manufacturing processes, more especially those employed in the smelting of lead and copper, and arsenical ores of various metals, have given rise to a gradual impregnation of the soil with such metals, and to the conse- quent poisoning of vegetation and animals. The possibility of injury to plants has been denied on the assump- tion that they select such elements of the soil as are nutritious and reject all else. Mr. Phillips has therefore undertaken experiments from which it seems safe to conclude: 1. That healthy plants grown under favour- able conditions may absorb, through their roots, small quantities of lead, zinc, copper, and arsenic. 2. That lead and zinc may enter the tissues in this way without causing any disturbance in the growth, nutrition, and functions of the plant. 3. That the compounds of copper and arsenic exert a distinctly poisonous influence, tending, when present in larger quantity, to check the formation of roots, and either killing the plant or so far reducing its vitality as to interfere with nutrition and growth. In the case of the heavy metals, copper, zinc, arsenic, and lead, it seems to be probable that their oxides may under certain circumstances become deposited in the tissues of the plant. As to the manner in which this takes place, authorities differ. It is supposed by Freytag and others, that plants absorb all soluble matters indiscriminately, through their numberless rootlets; that the absorption of poisonous metals causes no disturbance until a certain degree of concentration is reached, when the plant rapidly withers and dies ; that plants are therefore spared the sufferings of chronic poisoning, but are very susceptible to acute poisoning, which is invariably fatal ; while it is held by others that plants absorb only such elements as are essential and nutritious, refusing to take up what is poisonous or innutritious; metallic compounds found in the analyses are therefore to be traced to atmospheric deposit adhering externally. The theory of Freytag seems to the author to have the weight of facts in its favour, and if it is possible that crops may become charged in this way with poisonous elements of the soil, it becomes a matter of the highest importance that wherever there is danger of such impregnation the most efficient means be employed for its aversion; for soil once impregnated with copper, lead, and zinc, may year after year bear crops poisoned in the same manner. Decomposition of Calcium carbonate in the Stem of Dicoty- ledonous Woods.*—H. Molisch states that the deposition of calcium Pie K. Akad, Wiss. Wien, Ixxxiy. (1881). See Bot. Centralbl., x. (1882) p- 161. 528 SUMMARY OF CURRENT RESEARCHES RELATING TO carbonate in the wood of dicotyledonous trees is not a rare pheno- menon; but that it takes place only in the duramen or in parts of the alburnum which resemble the duramen in properties. In knots and wounded parts it is frequently separated in considerable quan- tities. It is deposited especially in the vessels and tracheides, less often in the libriform, parenchyma, and medullary rays. It occurs abundantly in the pith when the wood that is in immediate proximity — to it assumes the nature of duramen, and becomes filled with lime. An account is given of the different woods in which calcium carbonate was found. Hypochlorin.*—The investigations of Pringsheim + on the nature and mode of formation of hypochlorin have been gone over by A. B. Frank, with the following results :— The hypochlorin reaction is found by Frank to bear the most intimate relation to the presence of the colouring matter of chloro- phyll; and this connection is the only constant one, there being no relation to the presence or absence of conditions of assimilation. Hypochlorin is never present in any other part of the protoplasm than in that which is coloured by the chlorophyll-pigment, and here it appears to be universal, whether the chlorophyll be in the form of grains or spiral bands or in the amorphous condition. The hypo- chlorin reaction manifests itself along with the very first trace of the green colour in the young protoplasm, as was demonstrated in terminal buds of Elodea canadensis, where the cells of the young minute leaves are still in a merismatic condition, long before the differentiation of the chlorophyll into grains, and when it is improbable that any assimilation can take place. Hypochlorin is also found in the cell till the close of the existence of the chlorophyll-pigment, in conditions which exclude the possibility of assimilation. The hypochlorin reaction is invariably accompanied by a destruc- tion of the colouring matter of the chlorophyll. The first effects of acids on chlorophyll-grains is a change of the green colour into yellowish green or yellow, and this is followed by the separation of oily drops of hypochlorin. If, however, the cells are killed, no separation of hypochlorin takes place. Two conditions are therefore necessary for the separation of hypochlorin :—the living condition of the chlorophyll-grain, and the presence of an acid. The reaction may be induced by hydrochloric, sulphuric, nitric, phosphoric, acetic, lactic, tartaric, citric, picric, or salicylic acid, and with very various degrees of concentration. The cause of the change of colour of leaves in autumn is the disappearance of the protoplasm from the cells, in consequenee of which the chloro- phyll-grains come into contact with the acid cell-sap. The same changes take place when leaves become yellow from want of light. The author believes that in this case the chlorophyll is not destroyed directly by the want of light, but only by the secondary action of the acid cell-sap in consequence of the destruction of the protoplasm. * SB. Bot. Ver. Prov. Brandenburg, xxiii. (1822) pp. 11-16. { See this Journal, iii. (1880) pp. 117, 480; i. (1881) p. 479. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 529 In a different communication * J. Wiesner states his general con- currence with Frank’s conclusion, which he would carry somewhat further. From its impermeability to organic acids, Wiesner regards protoplasm as having for one of its functions the protection of chloro- phyll from injury from this source. The same process takes place also in fruits as in leaves. Latex of Euphorbia Lathyris-|—An elaborate examination of the latex of Euphorbia Lathyris has led J. Schullerus to the conclusion that it must be regarded neither as a product of excretion (waste product) nor as a reserve material, but as a substance of actual direct service to the nutrition of the plant. The following are some of the special results at which he has arrived :— The laticiferous tubes of «this plant originate even in the embryo, and exclusively in the cells contiguous to the cortical parenchyma ; no laticiferous cells being formed at a later period or originating in any other way. They are found during the whole life of the plant, and in all its parts, in the root as well as the aerial portion. They may branch, but do not anastomose, either in the nodes or leaves. The growth of these tubes does not depend on that of contiguous cells, but is independent of them and may even be restricted by their growth; they retain, during their existence, their power of apical growth and of branching at any spot. The latex of H. Lathyris is a formative sap, taking part directly in the processes of growth of the plant, and cannot be regarded as a mere reserve material. Its nutritive properties are proportionate to the amount of carbohydrate, especially starch, contained in it. When in an inactive condition it passes over to the state of a primordial latex. This is also the function of the latex of the permanent rhizomes of Euphorbia palus- tris, orientalis, Pithyusa, and trigonocarpa, rich in albuminoids, but containing but little carbohydrate. The absence of this property of storing up reserve materials distinguishes the laticiferous vessels physiologically from the cortical parenchyma. Besides osmotic movement, the latex possesses also a power of movement in mass, corresponding to the general movement of food-materials towards those parts where new formations are taking place, not due in any way to external influences. These facts regarding the physiological function of the latex of E. Lathyris are true also for that of other species of Euphorbia which do not differ from it by any very strongly marked characters. Darwin’s so-called “ Brain-function” of the Tips of Roots.t— E. Detlefsen has investigated in a series of fresh experiments, the peculiar properties attributed by Darwin§ to the extreme tips of * Bot. Centralbl., x. (1882) pp. 260-6. + SB. Bot. Ver. Prov. Brandenburg, xxiii. (1882) pp. 26-93. t Arbeit. Bot. Inst. Wiirzburg, ii. (1882) pp. 627-47. § “It is hardly an exaggeration to say that the tip of the radicle thus endowed, and having the power of directing the movements of the adjoining parts, acts like the brain of one of the lower animals; the brain being seated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements,”—Darwin, Zhe Power of Movement in Plants, p. 573. Ser. 2.—Vot. IL. 2N 530 SUMMARY OF CURRENT RESEARCHES RELATING TO roots, and has come to the conclusion that his statement of these properties cannot in all respects be substantiated. He states that the curvatures manifested by the roots when a foreign body is applied to them on one side, and which Darwin attributes to the sensibility of the roots, are really due to injury suffered by the root from the cutting off of free access of air, all the tissues being found to be destroyed up to the cylinder of plerome. That the cause of the curvature is injury to the root-sap is shown by parallel experiments in which the injury is inflicted in other ways. The statement of Darwin that it is only the apex of the root that is susceptible is also contested. Experiments with roots from which the tip had been entirely removed, showed the same geotropic phenomena as others in which the roots were entire. The author further disputes Darwin’s assertion that the apices alone of roots are susceptible to change in the degree of moisture of the environment; he states, on the contrary, that the whole of the growing part of the root, and not merely the tip, is affected by an unequal degree of moisture in the surrounding air, curving in the direction in which the air is most moist. Aerial Cultivation of Aquatic Plants.*—-E. Mer records the results of a series of experiments for the purpose of determining the effects produced by growing in the air plants which ordinarily grow entirely submerged in water. They were placed in a vessel of water in such a way that the buds were above the surface of the water, and the whole covered with a bell-glass ; others being, at the same time, grown under similar vessels entirely in water. The sun, in July, was powerful during the whole of the experiments. In Potamogeton natans and rufescens the shoots grown in the air were distinguished from the normal ones by the shortness of their internodes, the smallness of the leaves, which partially remained rudimentary, and the presence of numerous stomata, which were also found, but in small numbers, in the newly formed branches of the submerged specimens. The formation of stomata is ascribed by the author to the retardation of growth and to heredity. The accumulation of reserve-materials in the tissue resulting from the retardation may bring about divisions in the epidermal cells, and hence lead to the formation of stomata. The formation of stomata only in the parts exposed to air he attributes to more vigorous trans- piration. Similar causes lead to the formation of stomata on the perianth-leaves of P. rufescens and the foliage-leaves of Littorella lacustris. Hereditary tendency causes the localization of the stomata on the upper side of the leaves in P. natans, as is usual in floating leaves; it also produces the effect in Littorella that, when grown in the air, the newly formed leaves possess a larger or smaller number of stomata, according as the plants grew originally at a greater or less depth below the surface of the water. In Hydrocharis morsus-rane the size of the leaves was greatly diminished, as well as the length of the leaf-stalk, the intercellular * Comptes Rendus, xciy. (1882) pp. 175-8. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 531 spaces and epidermal cells were smaller, and the latter had somewhat wavy outlines. In Nuphar pumilum the leaves were smaller and contained less starch. ; The author concludes that the incapacity of certain water plants to produce branches outside the water depends on their inability to resist strong transpiration, and not on any incapacity to grow and nourish themselves in the air. They thrive in the air if it is only sufficiently moist to reduce transpiration to a small amount. Insectivorous Plants.*—A. EF. W. Schimper gives detailed descrip- tions of several insectivorous plants, natives of North America. In the first place, the structure is more fully described than hereto- fore of the ascidiform leaves of Sarracenia purpurea. It was clearly determined that the products of decomposition of the insects and other organic substances found in the pitchers enter the cells of the leaf, as is shown by the changes which take place in the protoplasm of the cells thus affected. In these cells Schimper noticed a pheno- menon closely resembling that described by Darwin as occurring in Drosera under the name “ aggregation of protoplasm.” In fact, how- ever, in Sarracenia, the aggregations consist of a concentrated solution of tannin, which substance is always present in the cell-sap. There occur in North America three species of Utricularia, land- plants growing in moist sandy situations. Of these U. cornuta was especially examined, and presents several very singular points of structure. The plant possesses no true root, the rhizome branching into several root-like organs, which bear the bladders in great quantities, and which the author believes to be homologous to the floating leaves of the aquatic species. The bladders are similar in form to those of U. vulgaris, but want the “antenne,” as is also their histological structure, which is described in detail. They con- tain, besides inorganic bodies, small animals and Alge, especially diatoms, rotifers, and crustacea; the animals were never found alive, but usually much swollen and decomposed, and this was also the case with the diatoms, the contents of the bladders being apparently poisonous to both animals and plants. The hairs of the bladders appear to act as organs of absorption; and in the contents of their cells similar changes were observed to those described in the cases of Sarracenia and Drosera. As in Dionca, an excess of nutriment is injurious to the plant. Climbing Plants.t—In opposition to the view of Von Mohl, S. Schwendener denies the existence of a special faculty of irritax bility to which the twining of climbing stems and tendrils is due. He considers all the phenomena of these organs to be explicable by the laws of circumnutation and of geotropism. Power of Movement in Plants.{—In J. Wiesner’s work on this subject he goes through the results published by Darwin in his work * Bot. Ztg., xl. (1882) pp. 225-34, 241-8 (1 pl.). t SB. Bot. Ver. Prov. Brandenburg, xxiii. (1882) pp. 9-11. { Wiesner, J., ‘Das Bewegungsvermégen der Pflanzen,’ 212 pp., Vienna, 1881. See Bot. Ztg., xl. (1882) pp. 202-8. See also ‘ Nature,’ xxv. (1882) pp. 578-82; 597-601. 2 NZ 532 SUMMARY OF CURRENT RESEARCHES RELATING TO bearing the same title, and in a great many points comes to a more or less different conclusion, his arguments being in all cases founded on actual experiments. The following are some of the more important points in which he differs from Darwin. As regards circumnutation, Wiesner doubts its existence in roots, attributing this apparent phenomenon to the antagonism between geotropism and the natural tendency to curvature existing in roots, first one and then the other of these forces getting the upper hand, and thus moving the tip of the root backwards and forwards. In the case of stems, also, he considers that there are some plants which do not exhibit circumnutation. Some leaves also, he states, grow in absolutely straight lines without circumnutating, the apparent cir- cumnutation being here again due to the varying action of opposing forces, viz. epinasty, apogeotropism, apheliotropism, and gravitation. Wiesner’s explanation of heliotropism agrees with that of De Candolle, that the convex side grows more quickly simply because it is in shade. The author disputes the value of Darwin’s experiments which are alleged to prove the sensitiveness of the tips of radicles, attributing the observed phenomena to injury resulting from the means em- ployed. Electrical Researches on Plant Forms,*—The absorption of water by porous bodies is accompanied by electric currents. When a porous earthenware cell is partly filled with water, and a current completed through a galvanometer by means of electrodes in the water and in contact with the outer wall of the cell, a current passes. The intensity continually diminishes, until it finally ceases, and then a current begins in the opposite direction from the cell-wall through the water. This reversal of current is due to the incomplete state of saturation of the walls of the cell. These phenomena are employed by A. J. Kunkel to account for various electric phenomena observed in plants. In regard to the electromotive action of the upper surface of green leaves, the difference of tension of the various parts was determined by a systematic method of contact over the whole surface, with the result that the leaf-veins are generally positive towards the rest of the leaf, but the direction of the current is reversed if the spot on the leaf where the electrode is placed is wetted before the other electrode is placed on the vein. Also a spot long moistened is positive towards one freshly wetted. When the electrodes rest on the epi- dermis of a plant and a wound is made near the electrode, then that electrode will be negative to the other. The same result is obtained by bending the plant, and the current formed is the more intense the greater the amount of bending, the electrode near the bend being negative to the other. Sometimes plants also show the existence of electric currents, which when the plant moves cause the galvanometer needle to oscillate. * Bied. Centr., 1882, pp. 28-30. Cf. Journ. Chem. Soe. Abstr., xlii. (1882) p. 638. ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 533 Electromotive Properties of the Leaf of Dionewa.*—Professor J. Burdon Sanderson has investigated the immediate and subsequent electrical results of excitation of the leaf of Dionea, which have pre- viously been examined by Munk, Kunkel, and the author himself. It is found that at the moment of excitation (whether mechanical or electrical) the under surface of the lobe of the leaf is electro-nega- tive to the upper surface, the difference of potential reaching its maxi- mum about half a second after excitation; it then rapidly decreases until the upper surface is ultimately electro-negative to the lower, and this after-effect remains constant for some time. With a current not much more than adequate, excitation occurs at the moment of closing the current, but none occurs on breaking the circuit unless the current be sufficiently strong. The author considers (1) that the difference of potential is due to the electromotive forces which reside in the living protoplasm of parenchyma-cells in contact with one another, and in ditferent states of physiological activity ; (2) that the second phase of excitation is probably dependent on the diminution of turgescence of the excited cells, arising from a migration of liquid; (3) this explanation cannot be accepted for the phenomena of the first phase, the sudden accession and rapid propagation of which show that it is probably analogous to the “negative variation ” or “ action current ” of animal physiology. Influence of a Galvanic Current on Growing Roots.t—F. Elfving has observed the effect of a continuous current of electricity upon the growing organs of plants, especially roots, and finds that it causes a distinct curvature of the organ in the direction of the positive pole. This curvature has not, however, any physiological significance, like those due to geotropism and heliotropism ; it is due to the retarding effect on growth of the current of electricity, especially on that side of the organ which the current meets directly. B. CRYPTOGAMIA. Cryptogamia Vascularia. Schizeacex.t—The second part of Prantl’s work on the Vascular Cryptogams is devoted to this group of ferns, and especially to the morphology of the non-sexual generation. The first section is occupied with the arrangement of the leaves on the stem and the structure of the leaves and stem. There occur both radial and dorsiventral stems, the most remarkable among the latter being Lygodium, which has a single dorsal row of leaves, this arrange- ment originating even in the growing point. A similar structure occurs also in other ferns. The genus Lygodium is also of special interest with respect to the structure of the sporangia. Each sporangium is here enclosed in a pocket, the upper wall of which is composed of the surface of the leaf * Proc. Roy. Soc., xxxiii. (1882) pp. 148-51. + Bot. Ztg., xl. (1882) pp. 257-64; 273-8. - t Prantl, K., ‘ Unters. zur Morphologie der Gefasskryptogamen. Heft ii. Die Schizeaceen.’ Leipzig, 1881. 534 SUMMARY OF CURRENT RESEARCHES RELATING TO itself, while the lower wall is a lamella of tissue springing from the outer part ofa vein. The sporangium springs, as in Anemia, from the margin of the leaf, while behind the sporangium is formed an annular wall, the indusium, which encloses the sporangium like a hood, the Sporangium becoming eventually placed, in the course of develop- ment, on the under side of the leaf. Such a sporangium, covered by an indusium, is termed by the author a “ monangic ” sorus. The apex of the young leaves is occupied by a wedge-shaped apical cell. In the finer veins the structure of the vascular bundles is collateral. No spiral vessels occur in the stem, and the sieve-tubes are very small. The mesophyll does not possess any true palisade- parenchyma, and is very nearly alike on the two sides of the leaf. The epidermis is not sharply separated from the fundamental tissue. In Anemia and Schizea the cuticle is provided with siliceous warts. In Anemia elegans the stomata occur only on the upper side of the leaf. Those of Schizea are arranged in two longitudinal rows on each side of the veins. As regards classification, Prantl divides the Filices into three primary groups, viz. (1) Hymenophyllacex, Polypodiacee, and Cya- theacesw ; (2) Schizeacex, Gleicheniaceze, and Parkeriacex; and (3) Osmundaces, Ophioglossacerw, and Marattiaceze. Ceratopteris he treats as belonging to the Schizeacez ; it has monangic sori, as also has Botrychium. The author regards the Schizzeacez as presenting the closest affinity among ferns to flowering plants. He inclines to the view that the nucellus of the ovule is homologous to the sporan- gium, and the entire ovule to a monangic sorus with its indusium. Muscinese. Branched Sporogonium of a Moss.*—C. Fehlner describes an instance of branched sporogonium in WMeesea uliginosa. From a common seta spring two sporangia, each with normal operculum and peristome. The capsule of Meesea not being regular, but laterally symmetrical owing to a curvature, the two sporangia are placed back to back in the same plane of symmetry, and the mutual pressure causes the surfaces which are in contact with one another to be some- what flattened. Leitgeb regards this and similar recorded cases of branched sporo- gonium as indicating reversion towards earlier forms of Archegoniatz in which the sporogenous generation is normally branched. He states that they do not result from the archegonium containing two oospheres, or from coalescence of two embryos, but from vertical segmentation of the apical cell of the embryo, which therefore branches when it has attained a certain stage of development. Influence of Light on the Thallus of Marchantia.j —A. Zim- mermann contests Pfeffer’s statement that the development of root- hairs from the gemmz of Marchantia is determined only by contact with the surface of the soil; he finds, on the contrary, that in addition * Oesterr. Bot. Zeitschr., xxxii. (1882) p. 185. } Arbeit. Bot. Inst. Wiirzburg, ii. (1882) pp. 665-9. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 to this contact and to gravitation, the absence of light is also a factor in determining on which side of the thallus the root-hairs shall be produced. Precisely the same results were obtained with gemma of LIunularia. The author confirms, on the other hand, the assertion of Pfetier that the organic upper side of the thallus of Marchantia is always the side which faces the light, This was determined by culti- vating the thallus both of Marchantia and Lunularia on the surface of water. He considers these observations to have an important bearing on those of Leitgeb and Prantl* on the bilateralness of the prothal- lium of ferns. Goebel’s Muscineze.{—In his most recent account of the Musci- nex, Dr. K. Goebel introduces no fresh element into the main principle of their classification. The Hepatice are divided into two main groups, the Marchantiacee (subdivided into the Ricciex, Cor- siniez, and Marchantiez) and the Jungermanniacexw (Jungermanniess and Anthocerotez). In the Musci he groups the Sphagnacez and Andreacez together as one type, the Phascacez and Bryinex together as a second type. In each group the various organs are treated in succession :—Firstly, the vegetative organs and the non-sexual mode of reproduction; then the sexual organs, and the development and structure of the second generation, ending with the structure and germination of the spores. A new instance of vegetative budding is described from the calyptra. In their genetic relationship, Goebel regards the Hepatice and Musci as two offshoots from the same stem, the lowest Hepatice pre- senting the nearest resemblance to the original stock. They ma possibly have sprung from the Thallophytes through Coleochete, the hibernating oospore of which presents no great diversity from the sporogonium of Riccia. In the ascending scale the Muscinex have no derivative forms, the series ending with them. Characee. Development of the Cortex in Chara.j—T. F. Allen employs the mode of development of the cortex as a new basis for the classifi- cation of the species of Chara, and distinguishes the following eight methods :— 1. Some species never develope cortex-tubes, and the stems remain naked (C. coronata Ziz.). 2. Some species develope a single cortex-tube, which is so small that it does not join the one from the next leaf (C. inconnexa Allen). 3. Some cortex-nodes develope spines, but no secondary tubes; the primary tubes join and completely encircle the stem (C. crinita Wallr.). 4, Some cortex-tubes show a partial development of secondary tubes (C. evoluta Allen). * See this Journal, ii. (1879) p. 917; iii. (1880) p. 121. + Goebel, K., ‘Die Muscinex.’ Encyklopedie der Naturwissenschaften, Ite Abtheil. 28 Lief. pp. 315-401. ¢ Bull. Torrey Bot. Club, ix. (1882) pp. 37-47 (8 pl.). 536. SUMMARY OF CURRENT RESEARCHES RELATING TO 5. Some cortex-tubes develope one secondary cell only, which becomes as long as the primary cell, but is of smaller diamet>r (C. excelsa Allen, C. intermedia A. Br., C. contraria A. Br. Sect. Tyla- canthz). 6. Some develope only one lateral cortex-cell, which becomes larger than the primary cell and partially covers it, so that the primary cell seems to lie in a furrow (C. fetida A. Br. Sect. Aula- canthee). 7. Some cortex-cells develope perfectly one lateral cell, and im- perfectly another (C. aspera Willd.). 8. Some cortex-cells develope perfectly both lateral cells, so that three complete series of cells arise from each leaf (C. fragilis Desv., C. gymnopus A. Br.). Details of the application of these characters are followed by full descriptions of the following new American species :—C. imconneaxa, evoluta, and excelsa. Fungi. Ustilaginese.*—The fifth part of De Bary and Woronin’s ‘ Morpho- logy and Physiology of Fungi’ is occupied by a treatise on the Ustilagineze by M. Woronin. The first section consists of a complete life-history of Tuburcinia Trientalis Berk. and Br., which attacks the stem, leaves, and rhizome of Trientalis europea. The mycelium consists of sparingly septated and irregularly branched hyphe which permeate the intercellular spaces, and put out haustorial lateral branches into the cells them- selves of the host; these branches, with their short irregular secondary branches, having somewhat the form of a bunch of grapes. On this mycelium are produced two kinds of reproductive organ, conidia and resting-spores. ‘The conidia are always borne on the under side of the leaves of the host, and form a white mould-like coating, the Ascomyces Trientalis of Berk. The hyphe on which they are borne form a more or less dense felt between the epidermis and the meso- phyll; lateral branches then penetrate through the stomata or between the walls of the epidermal cells, and bear the pear-shaped conidia, either first putting out haustoria or not. The conidia germinate readily in water, putting out a germinating filament, which either at once developes a conidiophore, or continues to grow without putting out conidia. Conidial hyphz are also produced by sowing conidia on moistened leaves of Trientalis, These give rise to small patches of mycelium, on which the resting-spores are developed. The resting-spores form brown Sorosporium-like masses, dusky patches $-2 mm. in diameter, on the leaves and leaf-stalk of the host. These spores are produced on much-branched mycelial filaments, which appear usually to be of smaller diameter than the purely vege- tative ones, to be more freely septated, and usually destitute of haustoria. In their youngest stage they have the form of straight or curved, spiral or twisted branches, either singly or in coalescent * De Bary, A., u. Woronin, M., ‘ Beitrage zur Morph, u. Phys. der Pilze,’ Part v. 35 pp. (4 pls.), 4to, Frankfurt a, M., 1882. is ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 5387 pairs. These become septated, and some or all of the cells become vesicular. Soon a number of these hyphe amalgamate into a dense ball, the vesicular cells at the same time increasing in size. In this way is formed a fructification, the interior of which is composed of the spores, polyhedral cells with ultimately thick and brown walls, com- paratively large and numerous (as many as 100). The filamentous envelope of hyphe ultimately gelatinizes and disappears. The process agrees in essential points with that in Sorosporium Saponarie. The resting-spores do not remain dormant through the winter, but germi- nate late in the autumn of the same year on the host, each of the spores germinating separately. The process corresponds to that in Tilletia, each spore putting out a promycelium, which forms at its apex a cluster of cylindrical-fusiform sporidia in groups of from four to eight. While they are being formed the protoplasm leaves the basal part of the promycelium, and becomes separated by a septum from the empty portion, the promycelium thus becoming bicellular. The sporidia are abstricted from the terminal cell, which Woronin calls the basidial cell, and compares with the basidium of the Basidiomy- cetes. Unlike Tilletia, it becomes completely detached from the other cells. Two sporidia frequently anastomose, a process which Woronin regards as one of conjugation. One of the conjugating sporidia de- velopes at its apex a secondary fusiform sporidium ; but this also takes place in those which do not conjugate. They may even produce tertiary sporidia. After the sporidia have become detached, the basal cell, if still containing protoplasm, may put out a germinating tube. The sporidia and conidia bear no resemblance to one another in form. The sporidia are carried to the ground by rain or dew, and in this form again reach the leaves or stem of the host, which they penetrate with their mycelia. In the second section, the author describes the mode of germina- tion of the spores of other species of Ustilaginex, which frequently differs in minor points from that of Tuburcinia, viz.:—Sorosporium Saponarie, Tolyposporium Junci, Thecaphora hyalina, Entyloma Ascher- sonii, E. Magnusii, and Melanotenium endogenum. In the third section these results are compared, and the group classified according to the mode of germination, as follows :— I. No sporidia are formed in germination. a. The spores put out long and copiously septated germinating filaments, which either are unbranched or the upper protoplasmic cell puts out lateral irregularly distributed branches. The terminal cell sometimes becomes detached, and carries on an independent existence—Sorosporium. b. The growth of the germinating filaments is limited, and they form a promycelium. They are septated, but instead of producing sporidia, put out filaments, which usually grow in opposite directions, and which conjugate at their apices, then developing the true germi- nating filament—Thecaphora. Il. The promycelium is septated into a number of cells, from each of which is abstricted one or more sporidia :—Ustilago-Schizonella (S. melogramma DC.), Tolyposporium. 538 SUMMARY OF CURRENT RESEARCHES RELATING TO TII. At the apex of the promycelium is formed a whorl of from two to eight usually fusiform branches, also termed sporidia, which usually conjugate in pairs, developing finally into secondary sporidia or directly into long, slender, simple or branched germinating fila- ments : — Tilletia, Entyloma, Melanotenium, Schroeteria, Urocystis, Tuburcima. The following species, nearly allied to Tuburcinia, are also specially described :—Thecaphora aterrima Tul., Sorosportwm schizo- caulon Ces., S. Miillerianum Thiim., Urocystis Paridis 'Thiim. (Soro- sporium Paridis Wint., Polycystis opaca Strauss, Urocystis Colchici f. Paridis ¥. vy. Waldh.), Tuburcinia Veronice Schrot., T. Cesati Sor., T. scabies Berk. Unobserved Sensitiveness in Phycomyces.*—F. Elfving has ob- served that if a moist disk of gypsum is brought near to growing Phycomyces, the sporangiophores will lose their upright growth and bend in various directions; and this will take place even if the atmosphere is saturated with aqueous vapour. The author suggests that the phenomenon is due to contact electricity. Beltrania, a New Genus of Hyphomycetes.t—Under the name Belirania rhombica O. Penzig describes a hyphomycetous fungus con- stituting a new generic type, found on the under side of fallen lemon leaves in Sicily, on which it forms an olive-coloured velvety coating. It presents most affinity to Fusicladiwm and Scolecotrichum, but differs from them in having sterile filaments in addition to the sterigmata, and the bicellular beaked spores collected in clusters on short basidia. The following is the technical description of the genus :— Cespitulis hypophyllis, stratum fusco-olivaceum constituentibus ; hyphis erectis vel adscendentibus, dense aggregatis, continuis vel 1-2-septatis, subsimplicibus, sinuosis; setulis sterilibus longioribus inter hyphas fertiles intermixtis; conidiis vel in hypharum apice sessilibus vel sterigmate ex apice oriundo suffultis, solitariis vel fasciculatis, 1-septatis, apice rostratis. Chemical Composition of Moulds.{—N. Sieber has prepared a srowth of pure Aspergillus, Mucor, and Penicillium, the absence of Schizomycetes being assured by the presence of free phosphoric acid in the nutrient fluid. An analysis of the alcohol and ether extract, of which the exact composition is given, showed that it consisted entirely of albumen and cellulose. Further experiments show that the form of albuminoid present was not that of mycoprotein. A very small quantity of an undetermined substance crystallized out of the extract. Salmon Disease.S—Professor T. H. Huxley, in his observations on this disease, not only examined the minute structure of both the healthy and diseased skin, but also tried some experiments on the * Bot. Notiser, 1881. See Bot. Centralbl , x. (1882) p. 76. + Nuov. Giorn. Bot. Ital., xiv. (1882) pp. 72-5 (1 pl.). { Journ. f. prakt. Chem., xxiii. (1881) pp. 412-21. § Proc. Roy. Soc., xxxiii. (1882) pp. 381-9. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 transplantation of the Saprolegnia of the living salmon to dead animal bodies. The body of a recently killed common house-fly was gently rubbed two or three times over the surface of a patch of the diseased skin of a salmon, and was then placed in a vessel of water, on the surface of which it floated, in consequence of the large quantity of air which a fly’s body contains. In the course of forty-eight hours, or thereabouts, innumerable white cottony filaments made their appearance, set close side by side, and radiated from the body of the fly in all directions. As these filaments had approximately the same length, the fly’s body thus became enclosed in a thick white spheroidal shroud, having a diameter of as much as half aninch. As the filaments are specifically heavier than water, they gradually overcome the buoyancy of the air contained in the trachee of the fly, and the whole mass sinks to the bottom of the vessel. The filaments are very short when they are first discernible, and usually make their appearance where the in- tegument of the fly is softest, as between the head and thorax, upon the proboscis, and between the rings of the abdomen. These fila- ments, in their size, structure, and the manner in which they give rise to zoo-sporangia and zoospores, are precisely similar to the hyphe of the salmon fungus; and the characters of the one, as of the other, prove that the fungus is a Saprolegnia and not an Achlya. Moreover, it is easy to obtain evidence that the body of the fly has become infected by spores swept off by its surface when it was rubbed over the diseased skin. These spores have in fact germinated, and their hyphe have perforated the cuticle of the fly, notwithstanding its comparative density, and have then ramified outwards and inwards, growing at the expense of the nourishment supplied by the tissues of the fly. This experiment, which has been repeated with all needful checks, proves that the pathogenic Saprolegnia of the living salmon may become an ordinary saprogenic Saprolegnia ; and, per contra, that the latter may give rise to the former, and they lead to the important practical conclusion that the cause of salmon disease may exist in all waters in which dead insects, infested with Saprolegnia, are met with ; that is to say, probably in all the fresh waters of these islands, at one time or another. On the other hand, Saprolegnia has never been observed on decaying bodies in salt water, and there is every reason to believe that as a saprophyte, it is confined to fresh waters. Thus it becomes, to say the least, a highly probable conclusion that we must look for the origin of the disease to the Saprolegnie which infest dead organic bodies in our fresh waters. Neither pollution, drought, nor overstocking will produce the disease if the Saprolegnia is absent. The most these conditions can do is to favour the development or the diffusion of the materies morbi where the Saprolegnia already exists. The results of the last season’s observations on the salmon disease appear to justify the following conclusions :— 1. That the Saprolegnia attacks the healthy living salmon exactly 540 SUMMARY OF CURRENT RESEARCHES RELATING TO in the same way as it attacks the dead insect, and that it is the sole cause of the disease, whatever circumstances may, in a secondary manner, assist its operations. 2. That death may result without any other organ than the skin being attacked, and that, under these circumstances, it is the conse- quence partly of the exhaustion of nervous energy by the incessant irritation of the felted mycelium with its charge of fine sand, and partly of the drain of nutriment directly and indirectly caused by the fungus. 3. That the penetration of the hyphe of the Saprolegnia into the derma renders it at least possible that the disease may break out in a fresh-run salmon without re-infection. 4, That the cause of the disease, the Saprolegnia, may flourish in any fresh water, in the absence of salmon, as a saprophyte upon dead insects and other animals. 5. That the chances of infection for a healthy fish entering a river are prodigiously increased by the existence of diseased fish in that river, inasmuch as the bulk of Saprolegnia on a few diseased fish vastly exceeds that which would exist without them. 6. That as in the case of the potato disease, the careful extirpation of every diseased individual is the treatment theoretically indicated, though, in practice, it may not be worth while to adopt that treat- ment. Formation of Saccharomyces in Nutrient Fluids containing various Proportions of Nitrogen.*—M. Hayduck finds asparagin especially well adapted as a source of nitrogen for Saccharomyces. The mineral ingredients of the nutrient fluid were a mixture of 50 g. acid potassium phosphate, PH,KO, and 17 g. crystallized magnesium sulphate; and the following results were obtained :— 1. The nitrogen contained in a nutrient fluid is assimilated by the yeast only up to a certain degree of concentration ; and above this limit the nitrogen is not used in the production of yeast. (2) In all the experiments an excretion of nitrogen was observed. (3) When formed in very dilute solutions the yeast contains a constant minimum proportion of nitrogen; as the proportion of nitrogen in the solution increases, the amount of yeast formed remains the same, while the proportion of nitrogen in it increases. But beyond a certain limit, the amount of nitrogen in the fluid increases neither the amount of yeast produced nor the proportion of nitrogen in it. (4) The fer- menting power of the yeast depends partly on the proportion of nitrogen contained in it. (5) Yeast containing a large amount of nitrogen can increase in a pure solution of sugar, a portion of the nitrogenous contents of the mother-cells being used in the formation of the daughter-cells. (6) The growth of the yeast may be affected by the formation of one or more products of fermentation, alcohol especially exerting a prejudicial influence upon it. * Zeitschr. f. Spiritusindustrie, 1881, p. 173. See Bot. Centralbl., x. (1882) p- 153. * ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 541 Morphology and Genetic Relationship of Pathogenous Bacteria,* —Dr. T. Haberkorn thus sums up the results of a series of observa- tions on this subject:—(1) The four tribes of Cohn, spherobacteria, microbacteria, desmobacteria, and spirobacteria, cannot be maintained ; these being all forms of a single genus with numerous species. (2) The history of development of the bacteria of malaria, typhus, and acute contagium is essentially the same, including pleomorphy and a definite alternation of generations. (3) Each of these diseases is accompanied by a distinct species of bacterium; typhoid having also one of its own. (4) The various species of bacteria are dis- tinguished by. their conditions of existence, ‘size, colour, habit, movements, and metastasis. Pathogenous Bacteria.j—V. Babes has convinced himself that there are no bacteria in the blood or the tissues of healthy men ; this judgment is based on the personal examination of more than one hundred bodies. He once observed the growth of filaments of Bacillus anthracis from spores in the sexual organs of a woman. Bacterian colonies, and not rods only, were observed in a case of Anthrax intestinalis; other examples of similar phenomena were observed, and weaken the generally accepted doctrine that rods alone are found in the living body. The author has for a long time used aniline green and aniline violet as colouring agents. Bacterium of Charbon.{—The temperature which seems most favourable to the bacterium of charbon, is that of mammalia (37° C.). Birds, having a higher temperature (about 42°), do not take the disease under ordinary conditions. Pasteur, however, has developed it in fowls by lowering the temperature (keeping the feet in cold water). M. Gibier has now experimented with frogs, and finds that they- do not suffer after inoculation in the normal state; but if kept, after being inoculated, in water at about 37°, they may take the disease (five out of twenty did—most of the others died soon after immersion). The bacteria developed were remarkable for their great length, and this is attributed to the slowness of the circulation. Connection of Bacteria with Ferments.§—J. Rossbach finds that the death which ensues in one to two hours after the injection of papayotin into the rabbit is accompanied by the appearance of large quantities of bacteria in the blood. These were ascertained to be entirely absent before the injection; but introduction of as small quantities as 0°05 to 0-1 gramme of this substance resulted, after death, in the presence of a large number of moving globular and “ hour-glass-shaped ” bacteria in every drop of blood taken from the heart. Thus it appears that the presence of a small quantity of an unorganized and purely chemical substance is sufficient to produce in the body conditions which induce the rapid multiplication of micro- phytes already existing there in insignificant quantities. This * Bot. Centralbl., x. (1882) pp. 100-6. t Biol. Centralbl., ii. (1882) pp. 97-101. $~ Comptes Rendus, xciv. (1882). § Medic. Centralbl., xx. (1882) p. 81. Cf. Naturforscher, xv. (1882) p. 224. 542 SUMMARY OF CURRENT RESEARCHES RELATING TO supports the view that chemical poisons or ferments play an important part in the injections connected with organic germs. Lichenes. Life-history of Cora.*—The genus Cora, established by Fries, has been regarded by some as belonging to Algez, by others as belong- ing to Fungi, while Nylander, who detected the true fructification as consisting of apothecia and ascospores, maintained it to be a lichen. O. Mattirolo has carefully examined all the known species, and fully confirms Nylander’s view. In the thallus is a well-defined gonimic layer, the gonidia belonging to the genus Chroococcus. One species, Cora ligulata Kremp., must be erected into a distinct genus in which the gonidia have a Scytonema-form ; Mattirolo proposes for it the name Bhipido- nema. 'The author has not been able to confirm Nylander’s account of the occurrence of apothecia, which probably belonged to a different lichen or fungus. Both Cora and Rhipidonema have on the under side a true hymenium, something like Thelephora or Kneiffia, formed of basidia which are the apices of special hyphe. Hach basidium bears a sterigma, on which is a single spherical spore, as in Kneiffia. The author holds, therefore, that we have in these two genera lichens in the building up of which Basidiomycetes, and not Ascomy- cetes, have taken part. This new group he terms HymEnonicHEnns, and places them among the Basidiomycetes, near to Kneifia, Corticium, Stereum, Thelephora, and Hypochnus. It includes the following species: —Cora Pawonia, glabrata, gyrolophia, and Neesiana, and Bhipidonema ligulata. They are all extra-Kuropean, and abundant in the tropics. Minks’s Licheno-mycological Symbols.j—In his last essay on the structure and affinity of lichens, Dr. A. Minks recapitulates the grounds of his microgonidial theory,{ and recommends Leptogium myochroum as a specially favourable species for establishing the existence of microgonidia. The ascus of a lichen he regards as simply a highly differentiated hypha, the terminal cell of which has the power of dividing so as to produce the spores. Neither in the history of their development nor in their structure do the spores correspond to the ascospores of the true Ascomycetes; and their mode of germination is also different. The portion already published of Dr. Minks’s work includes descriptions of 170 species ; and the whole family is intended to be gone through at the rate of about 200 species per annum. Alge. Symbiosis of Alge with Lower Animals.§—Since so many naturalists have published observations on this subject, Dr. G. Entz * Nuoy. Giorn. Bot. Ital., xiii. (1881) pp. 245-67 (2 pls.). + Minks, A., ‘Symbolee licheno-mycologice,’ Part I. Cassel, 1881. t See this Journal, ii. (1879) pp. 311, 931. § Biol. Centralbl., i. (1881) p. 646. Cf. Naturforscher, xv. (1882) pp. 93-4, and this Journal, ante, p. 241. ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 543 takes occasion to call attention to some results of his own, published in Hungarian in 1876. From a study of the chlorophyll-bodies of Infusoria, he had come to the conclusion that their presence there was not distinctive of any special group of Infusoria. These bodies only occurred in omnivorous species; and those species in whom they occurred in abundance were noticed to take in no solid food, but only to agitate water in their cesophagus. He characterized these green bodies as Alge, and stated their relation to their hosts as being a perpetual source of nutriment to the latter, which in their turn furnish them with a safe domicile; the Infusorian supplies the alga with carbonic acid, while the alga produces oxygen for its host. “We have thus to do in this case with a fellowship or peculiar consort relation between two totally different organisms, which may be compared in some respects to the organization of the lichens, which, according to Schwendener’s interpretation, owe their existence to the association of a fungus with an alga.” Entz has subsequently continued his study of this question, and has been able clearly to see a nucleus in these chlorophyll-bodies, and to determine that the mass is generally invested by a hyaline gelatinous envelope, and thus exhibits all the characteristics of the Palmellacee. He finds that the zoospores of various low Alge and green Flagellates as well may become converted into these ‘‘ pseudo-chlorophyll-bodies.” Division of the Cell-nucleus in Spirogyra.*—I. Tangl gives the following results of observations on an undetermined species of Spirogyra :— 1. The membrane of the cell-nucleus, when at rest, has a reticulate structure; but the author was unable to determine whether this was the result of local differences in density, or of actual perfora- tion. 2. The nucleus contains, as a rule,only a single nucleolus, and includes, when at rest, besides the nucleolus, a finely granular mass, very poor in substance, and only slightly tinted by colouring re- agents; the nucleolus is bounded by a membrane which is not tinted. 3. The nuclear spindle, the formation of which is preceded by demonstrable changes in the contents, is of the type described by Strasburger, and consists of equatorial rod-like elements which are not separated. 4, The portion of the original contents present in the “ spindle- stage” of the nucleus, and only slightly tinted by reagents, is subsequently resorbed during the formation of the daughter-nuclei. 5. These facts appear to corroborate Strasburger’s view that the spindle-fibres are derived from the protoplasm which is forced into the nucleus. 6. During the separation of the two halves of the nuclear plate a uniting tube is formed, proceeding from the membrane of the nucleus which is already perforated at the two poles at the “ spindle- * Anzeiger K. Akad. Wiss. Wien, March 30, 1882. See Bot. Centralbl., x. (1882) p. 189. 544 SUMMARY OF CURRENT RESEARCHES RELATING TO stage,” and the enveloping membrane of the nucleolus, the inner surface of which is closely applied to the uniting threads. 7. This combining tube constitutes the lining of an internal cavity of the mother-cell, which is relatively very large at a certain stage of the division, and which is closed outwardly by the rudiments of the daughter-nuclei. The further behaviour of this tube corre- sponds to that of the uniting threads in the species described by Strasburger. Batrachospermum.*—G. Arcangeli describes in detail several species of Batrachospermum, among them one new one, B. Julianum, found in thermal waters near Pisa. He describes the genus as pre- senting, in the same species, two modes of multiplication of cells, by segmentation and by gemmation. The former occurs in the terminal cell of the stem and of the primary branches, and is the mode by -which these organs lengthen, also in the cortical branches; while the verticillate branches are formed and lengthen by gemmation. Ata short distance from the terminal cell of the stem and of the primary branches, the rudiments of the verticillate branches make their appearance in the form of hemispherical protuberances, which separate themselves from the mother-cell by means of a tangential septum. B. Julianum differs from the other species in the mode of develop- ment of the female organ, presenting a considerable resemblance to that in Nemalion; and the author considers that it establishes an intimate relation between the mode of fertilization in Batracho- spermum and in the Florides. Although the thermal water in which B. Julianum grows, produces also a species of Chantransia, he was unable to detect any genetic connection between these genera, as stated by Sirodot. New Beggiatoa.t—A. Engler has observed the barren salt ground in the neighbourhood of the harbour at Kiel to be densely covered with the dusky white filaments of several species of Beggiatoa, especially B. alba Vauch. var. marina Cohn (B. Cirstedii Rabenh.). Attached to the legs of crabs in the deep water of the same harbour he finds a new species, not corresponding completely to any hitherto described, which he calls Beggiatoa multiseptata. Associated with it is another form, resembling Cladothrix, but not belonging to the Schizomycetes, which Engler regards as the type of a new genus, and names Cladomyces Mebiusii. It must be placed near Stigeoclonium. Vampyrella.t—J. Klein attempts to answer the question whether this organism is animal or vegetable, and has for this purpose examined four species, three of them new, Vampyrella variabilis, inermis, and pedata. In the resting condition Vampyrella forms, according to the species, stalked or sessile capsules, attached to various fresh-water Algz. A more exact description is given of V. variabilis, which occurs in * Nuov. Giorn. Bot. Ital., xiv. (1882) pp. 155-67 (2 pls.). + SB. Bot. Ver. Prov. Brandenburg, xxiii. (1882) pp. 17-20. + Bot. Ztg., xl. (1882) pp. 193-200, 209-17 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 545 the form of globular, ellipsoidal, or irregular cysts in the empty cells of fresh-water conferve. When ripe the contents are reddish, orange- yellow, or bright red, including a dark spot. The endochrome sub- sequently escapes in two, four, or more masses, which, as they gradually escape from the cyst, are clothed at the edge with a fringe of cilia, the dark body remaining still enclosed within them. The escaped ciliated bodies must be regarded as zoospores, and are provided with pseudopodia, moving about slowly with an amceboid motion. When two meet, and their pseudopodia come into contact, they slowly coalesce, and this the author regards as a kind of conjugation. The resulting bodies appear to be of the nature of plasmodia, are endowed with a creeping motion, and may again coalesce. These larger bodies attach themselves to certain alg, ultimately become encysted, and then again go through the same course of development. Those zoospores which do not conjugate also become eventually encysted. Attached to the conferva are also found cysts of the Vampyrella of a different kind, resting cysts which remain for a time in a dormant condition before any further development takes place. Vampyrella pendula and inermis agree with V. variabilis in essential characters, while V. pedata differs in some important points, and may, perhaps, be the type of a distinct genus. It is found, like the two last species, attached to Cidogonium; its zoospores have neither cilia nor pseudopodia, but a long projecting colourless beak, which is in front during the motion of the body, and appears to guide its movement by bending in different directions, finally becoming encysted, apparently without conjugation. These bodies have been described by zoologists as rhizopods (Hyalodiscus rubicundus Hertwig and Lesser, and Plakopus ruber F. E. Schulze). A full description follows of seven distinct species of the genus ; and the author concludes, taking all the points of structure into con- sideration, that Vampyrella is most nearly allied to the Chytridiacez and Myxomycetes, and must be regarded as a plant; but that it exhibits in some respects a transitional character to the animal kingdom. Schizophycex.*—W. Zopf has undertaken a fresh examination of the lowest forms of Algz, with the special object of determining whether the filamentous forms Scytonemee, Oscillaries, &c., and the non-filamentous or Chroococcacee may be different stages of develop- ment of the same organism. Pure material was obtained by allowing the filaments of the alga under examination to creep along the wall of the vessel, and collect above the level of the water in tufts or pellicles. These were then cultivated in boiled water or on disks of porous clay, which had also been exposed to a high temperature, and placed in large glass vessels in moist boiled sand. The dead cells of water-plants, as Lemna, Utricularia, &c., and the shells of certain of the lower animals, like Cypris, were also used as nurseries for the filamentous Schizophycee, and in them the formation of chroococ- caceous forms was especially well followed out. * Bot. Centralbl., x. (1882) pp. 32-6. Ser. 2.—Vot. II. 20 546 SUMMARY OF CURRENT RESEARCHES RELATING TO The author describes in detail the development under these circumstances of nine different filamentous species; and arrives at the following general conclusions:—(1) That the relationship between the Schizophycee and the Schizomycetes is much closer than has hitherto been generally believed, confirming the classification adopted by Cohn and Sachs of including these two families in the same group of Schizophyta. (2) That a new impulse is thus given to the study of the Schizophycee. (8) That the formation of zooglea is a more widely spread phenomenon than has hitherto been supposed, as is illustrated in Cienkowski’s observations on Ulothriz, Cylindrocapsa, and Gleothamnion. The results obtained tend also to the conclusion that many other members of the group of Chroococcacee are merely stages of development of filamentous Schizophycee. Motion of Diatoms.—Prof. Hamilton L. Smith considers* that Mr. C. M. Vorce’s paper on this subject t is marked by careful, well- matured statements, and that the conclusions at which he has arrived are quite correct. He has not the least doubt that the diatoms are enveloped by a membrane, out of which the stipes, tubes, &c., are formed. “'The movements, so curious and so varied, are yet con- nected with the structure of the frustule, and we must not ignore this in attempting to explain them, e.g. the Nitzschie, which have a con- tinuous raphe, that is, without median nodule or break, move in the most lively manner, they are also long and slender; the stalked forms move when free, Cocconema, for example, in a long curve, Gompho- nema, straight ; the Navicula group move in straight lines, but not in so lively a manner as the Nitzschiw. All these, except the last named, have a median nodule. The Surirellew, which have the raphe along the four expansions, or ale (two for each valve), move more sluggishly, rolling over frequently, and the Amphiproree and other twisted forms rock or twist as mentioned by Mr. Vorce, while the circular forms, like Coscinodiscus, which have the raphe probably all round the margin of the cingulum or connecting zone and edge of the valve, do not move at all, or if so, very sluggishly. The movement then is more or less regulated by the structure of the frustule, and in any explanation we must not forget this. The careful observation of facts meanwhile should not be neglected, and the publication of them may give the clue or hint that will guide some other observer, possibly, to the true solution of a phenomenon as marvellous as it is at present inexplicable.” * Amer. Mon. Micr. Journ., iii. (1882) p. 85. t See this Journal, ante, p. 394. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 547 MICROSCOPY. a, Instruments, Accessories, &c. Lossner’s Tele-microscope.*—O. M. Lossner has patented an instrument under this name. The objective forms a reduced image of a somewhat distant object, and this is enlarged by an ocular of four lenses. The construction of some is in hand, and “if suc- cessful this instrument, even if only for small enlargements, will, without doubt, be a welcome tool for the observation of living insects, &e.” Prazmowski’s Micrometer Microscope.— This Microscope (Fig. 91) was designed by M. Prazmowski for investigations in Fic. 91. “teen th Sl ——-+ ai en iis 1 iat te Rix, = —— er which measurements are to be recorded, and when it is also required to note precisely the angle of the illumination, &c., for purposes of repetition. We believe that it was made upon a special order (and not subsequently reclaimed), so that M. Prazmowski must not be * Centr.-Ztg. f. Opt. u. Mech., iii. (1882) p. 108. 0 548 SUMMARY OF CURRENT RESEARCHES RELATING TO considered as endorsing any practical value in the instrument as a whole. The principal micrometric movement is controlled by the gradu- ated milled head A working on a fine steel screw against springs, by which the rectangular framework carrying the optical body is moved in a direction at right angles to the vertical main limb and parallel with the stage. The optical body, with rack and pinion for coarse adjust- ment, fits loosely into this carrier ; it can be adjusted concentrically with the rotating stage by the action of side screws together with the micrometer-screw at A, and can be clamped in position by a screw- collar beneath. The fine-focussing is effected by the micrometer-head B working on a screw against a spiral spring on the main limb; the whole of the optical portion is thus moved together in focussing, as 1s usual in Continental Microscopes. ‘The eye-piece has a goniometer circle C attached, and is provided with a movable disk of glass with crossed lines in the usual position of the eye-piece micrometer, by which accurate determinations of angles in azimuth can be made while the object is stationary, &c. The rotating stage is of simple construction, similar to that on ordinary “turntables”; it is held in position by an indented key-piece (metal knob shown under stage) that slides into a circular rotating groove beneath, and can be removed at pleasure—the main rectangular stage is then only =3,th inch in thickness, and is fitted with a wheel of diaphragms, also removable. The mirror D is mounted in a gimbal sliding on a bar with lateral motion ; the three axes of motion are each provided with a graduated disk and pointer, so that exact record of the position can be made. The condenser E. is mounted to slide on one of the feet, and can be adjusted variously to direct the light upon the mirror. The two back feet close up against the front one for convenience of packing. Simplified Reading Microscope for horizontal and vertical circles.*— Herr Hensoldt, of Wetzlar, claims to have made a great-im- provement in the application of the compound Microscope toinstruments of medium size, such as theodolites of from 12 to 20 em. in diameter of limit. Whilst universally used for the larger, especially astrono- mical instruments, a Microscope has been found to be inconvenient for others, principally on account of the projecting micrometrical screws and the length of the body hitherto found necessary. The author says that he “has succeeded in reducing the length of the Microscopes to a most considerable extent by the selection of favourable qualities of glass, and by suitable construction of the lenses. With a power of from 45 to 50 diameters, they only possess a length of 5 cm. and an outer diameter of 16 mm., reading up to 12, and between the objective and the division there is suffi- cient room to affix a little illuminator, which throws a more than sufficient amount of light on the division. The latter appears very clear and distinct, and if the limb is provided with a glass cover, the objectives of the Microscopes are constructed accordingly, so as not to lose in definition. * Zeitschr. f. Vermessungswesen, viii. Transl. in Eng. Mech., xxxiv. (1881) pp. 83-4 (1 fig.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 549 “The Microscopes are provided with adjustable eye-pieces, to render the division of the micrometer distinct for every eyesight, and at the lower end is a short draw-tube, by means of which a small alteration in the magnification can be effected, whereby the intervals of the micrometer (previously determined by calculation) can be brought to accurately harmonize with the division of the circle. “ As the field of view, though as extensive as possible, cannot be so large as to always include figures of the divided circle, an index with a magnifying lens must be fixed at any desired point, by means of which the reading of the angle up to the nearest division of the circle is obtained, while the determination of the excess is effected by the Microscopes.” The divisions of the circle with which the Microscopes are used are not carried to any great degree of minuteness. The degrees are, for instance, divided into sixths, or 10',and the micrometer consists of ten equal divisions, representing, therefore, minutes, and the latter can then be mentally subdivided with great facility. An important advantage is, the author considers, obtained by the small number of graduations of the micro- ate ae meter, which permits an ae easy, rapid, and accurate reading, which does not occupy so much time as in the case of verniers. Swift's. Tank Micro- scope.—This, Fig. 92, con- sists of the stand of a bull’s- eye condenser to which are attached two additional short arms, the upper one carrying the microscope- tube and the lower a re- volving cork-holder and forceps for flowers or other objects suitable for low powers. The tube has a rack-and-pinion movement and the arm to which it is attached can be raised or lowered on the standard —_— and clamped in any posi- == tion. The tube can also be rotated on the arm so as to be either vertical or horizontal, or it can be removed from the arm altogether. Teasdale’s Field Naturalist’s Microscope.—This (Figs. 93 and 94) is made by Messrs. Field of Birmingham, and was designed by Mr. W. Teasdale with the view of providing the working microscopist with a really cheap and efficient dissecting Microscope, and it may be readily certified that it fully accomplishes these objects. “It is so simply and substantially made that it * - 550 SUMMARY OF CURRENT RESEARCHES RELATING TO im . Fic. 93. i) ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 551 may be used by an intelligent child, as well as by the experienced microscopist. It was termed a ‘Field Naturalist’ rather than a ‘Dissecting’ Microscope to disarm the suspicion with which some people look upon an instrument with the latter name as a rack or means of torture for frogs, &e.” The woodcuts render any detailed description of the instrument unnecessary, and we need only call attention to the sloping rest for the hands and that there are three lenses, a condensing lens, forceps, and live-box. The lenses drop into the arm which carries them, and also into each other, so that they may be used in combination, producing seven powers in all. Marshall’s turntable can also be used with the instrument, the spindle passing through a hole in front of the stage, and its point revolving in a brass socket below. Steinheil’s Achromatic Eye-pieces.— These eye-pieces (?in. and } in.), exhibited and described by Mr. Ingpen at the June meeting of the Society, are shown in Figs. 95 and 96 in section. They are especially adapted for micrometry. They consist of a double convex lens of crown between two meniscus lenses of flint, all cemented together. Grooves cut in the edge and blackened, form diaphragms as in the Coddington lens, New Combination for Objectives.*—The following is the whole of the note by C. V. Zenger under this heading published in the ‘ Comptes Rendus’ :— “The author proposes to obtain an amplification equal to 2000 with a large focal distance. It would then be possible for anatomists and physiologists to carry on their dissections and preparations with a very considerable amplification, at a distance from the objective equal to 4 mm. or 6 mm.” Fluid for Homogeneous Immersion.t—Professor Abbe finds that pure cedar-oil may be prepared so as to render it much less fluid than in its ordinary condition. By spreading it out in thin layers and exposing it for a long time to the influence of air and light, it becomes of the consistency of castor-oil, and without any increase in dispersive power, its refractive index is raised to 1°518-1°520. If desired, the index can of course be reduced to 1-510 by the addition of olive or castor oil. Dr. L. Dippel considers that this fluid unites in itself all the properties required for such a fluid, and that it makes all others superfluous. Shurley’s Improved Slide for the Examination of Gaseous Matter.t—Dr. E. L. Shurley describes an apparatus for the examina- * Comptes Rendus, xciv. (1882) p. 1542. + Bot. Centralbl., x. (1882) pp. 224-5. t Proc. Amer. Soc. Micr., 4th Ann. Meeting, 1881, pp. 65-8 (1 fig-). Fic. 96. 552 SUMMARY OF CURRENT RESEARCHES RELATING TO tion of aerial or gaseous material, with the higher power of objectives, without subjecting it to any previous manipulations, thus enabling one to collect and immediately examine with any objective, “even a ss or perhaps a = inch.” The apparatus consists of a rubber bag (Fig. 97) with a tapering, hard rubber nozzle, into which is inserted a perfectly tight fitting stopcock. A piece of soft rubber tubing } inch in diameter and about 2 feet long is furnished at one end with a metal collar, to be inserted into the outer end of the brass canule of the slide; while the other is to be slipped over the nozzle of the bag. The larger extremity of a small canule about 13 inch long, is fixed by a binding screw into the upright B on the glass slide, while its small end is inserted into the minute hole at the side of the cell. The larger extremity is smoothly ground, to receive the metal-finished end of the conducting tube. The slide has an ordinary cell A (of rubber). The cell has its middle portion built up from the bottom by a piece of glass, so as to bring it within the working distance of the objective, allowing depth enough at the sides, which may be com- pared to two. ditches, for the introduction of a canule of reasonable Fic. 97. calibre. This, the author says, is an important point, inasmuch as a cell shallow enough for the adjustment of its bottom to the focus of a first-class 4-inch objective, could have a depth of only about a fortieth of an inch, and of course for higher powers less, altogether too shallow to allow of the introduction of a canule of practicable size. But, upon this plan, the cell may be built up ever so much, even for adjustment of a ;!,-inch objective, while yet at its sides will remain the same depth of ditches, or sulci, for the ingress of the gas. The cover-glass may be cemented on, or laid on loosely. In the former case the opposite side of the cell must be perforated to allow ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 553 the gas to escape, while in the latter case it escapes by itself lifting up from time to time the cover-glass. As all objects or particles contained in the air or gas must be at rest when examined with the higher power objectives, it will be necessary to coat either the bottom of the cell, the cover-glass, or both, with something to which the material will adhere as the gas passes through. One of the best methods is to coat both the bottom of the cell and under side of the cover-glass with a thin layer of glycerine—somewhat after Beale’s method of collecting aerial germs. This coating is easily accomplished by previously moistening the glass with alcohol. The rubber bag and connecting-tube may be cleansed by drawing alcohol into them, and after expelling this they may be easily dried, if desired, by drawing and expelling air for awhile. All the parts being in proper connection, by opening the stop- cock of the receiver, and gently pressing upon it, the cell may be supplied at will. As before stated, any gaseous material can be collected and kept any length of time from the access of air, and when desired, directly examined under the Microscope without any intermediate manipulation; ‘‘a great desideratum and one which cannot be attained so far as I have been able to learn, by any other slide or apparatus hitherto in use. Those most used are the ‘Stricker’ and ‘ Hunt’ gas slides, the Holman ‘life slide,’ and the animalcule cell or cage, none of which is applicable in examinations with the higher power objectives; and none of which, excepting one, is arranged so as to allow of the direct introduction in small quantity of gaseous material. The advisability, nay, the necessity, of more perfect means for the examination of aerial or gaseous matter, must have been felt by every one who has ever attempted any work in this direction : and it is obviously only by patient investigation with high- power objectives that we can hope to discover the nature and habitat of those infinitesimal organic poisons which are supposed to originate in some unknown way the so-called zymotic diseases.” Hardy’s Compressorium.*—Mr. J. D. Hardy’s object in con- structing the compressorium shown in Fig. 98, is to remedy, to some extent, the defects of existing compressors as regards the difficulty Fig. 98. of regulating the pressure with exactness, the imperfect parallelism, and a deficiency of freedom of action, which causes great risk of losing or damaging the object under observation. * Journ, Quek, Micr. Club, i. (1882) pp. 35-6 (2 figs.). 04 SUMMARY OF CURRENT RESEARCHES RELATING TO A is a brass plate, 3 inches by 14 inch, in the centre of which is a round hole. At one end is a bent spring B, of thin brass, to which is hinged a second brass plate C, also with a central round hole, and bevelled on the upper surface for high powers. This second plate will, when turned down, overlie the plate A, and the two apertures will correspond. At the other end of the plate A, a button D is mounted so as to turn freely, and to rock on a short stud pind. The outer extremity of this button is bored and tapped to receive a small thumb screw e. A similar thumb screw / is also fitted to the plate C, near its hinge joint. A thin cover-glass is cemented to the upper side of the plate A, so as to cover the central hole, and the under side of the plate C is similarly provided. The mode of using this compressor is as follows:—The plate C is first turned down into place, and the distance that it is desired the glasses should be apart roughly adjusted by means of the screw /. The plate C may then be turned back, and the object placed on the lower glass; the covering-plate is then again turned down and secured by turning the button D over it. By means of the two screws d and f, the pressure can now be regulated with the greatest nicety without any risk of damaging or losing the object under examination. The arrangement admits of the glasses being easily cleaned and readily replaced by new ones when broken. Bulloch’s Diatom Stage.*—Mr. W. H. Bulloch has made a supple- mentary stage for use in arranging diatoms. It fits into the substage ring, and a stem projects up through the hole in the main stage. Upon the stem there is an arrangement like a double nose-piece, which carries two glass slips. One of the slips is intended for the material from which the diatoms are to be selected; the other for the prepared slide upon which they are to be mounted. The two slips can be moved about independently upon their supports. The hair or bristle is mounted on the mechanical stage. The slide carrying the material is first focussed, the diatom picked up, and the supple- mentary stage turned until the clean slide is in focus, when the diatom is placed in position. Substage Fine-adjustment.—At the suggestion of Mr. HE. M. Nelson, Messrs. Powell and Lealand have recently applied a fine- adjustment to their substage specially for use with their achromatic condenser. Fig. 99 shows (half-size) the under side of the substage with the new fine-adjustment in which A is a milled head controlling a screw-spindle terminating in a steel cone B. On rotating A, B turns and with a very slow motion forces up (or releases, as the case may be) a pin C inserted in the base-plate E of the substage. This motion of C carries with it the condenser. At right angles to, and forming part of H, at the back, an inner sliding plate works against a spring at the upper end between bearings F' at each side, which are fixed upon the usual racked slide D of the substage; this inner * Amer. Mon. Mier. Journ., iii. (1882) p. 97. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 555 sliding plate is the essential addition to the usual racked slide in the application of the new fine-adjustment to the substage. The range of motion is about } inch — the difference in radius between the smaller and larger ends of the steel cone. eS Ore Mr. Nelson states that he has * yi found the fine-adjustment on the fx ; substage of service in difficult in- ilk | qo vestigations with the condenser | in the axis. By this means he can readily exhibit the transverse lines of A. pellucida without any diaphragm. Sidle’s Centering Substage. —We gave a figure of Messrs. Sidle’s “ Iris” diaphragm in Vol. IIT. (1880) p. 1053, and briefly alluded to the centering arrange- ment of the substage as “a short bar working with a loosely fitting slot, that can be clamped beneath,” which is characterized as a somewhat primitive contrivance. Messrs. Sidle now adopt in their “Acme No. 2 Binocular,” the method of centering shown in Fig. 100, the special feature of which is that the substage motions are controlled by Fre. 100 two milled heads (right and left) on mie ES the arm or bar-attachment at the back of the substage carrier, racking on the swinging tail-piece. By this system the usual outer substage-ring, with its projecting centering screws (so generally adopted in America), is done away with. The forward mo- tion is given by the left-hand milled head acting on rackwork ; the lateral motion by the right-hand milled head acting on a pointed screw against a U-shaped spring that presses the slide towards that side, the fixed end of the spring being attached to the main base- or angle-plate racking on the tail-piece. We have not yet seen this mechanism, but with good workmanship we should anticipate the plan to be practical—certainly much better than the former system of centering by the rough process of pushing, pulling, and clamping by hand, which did not suggest the possibility of accurate centering. Mounting for the ‘‘Woodward” Prism.*—Dr. J. Edwards Smith recommends the form of mounting the “ Woodward” prism shown in * «How to Work with the Microscope’ (Svo, Chicago, 1880) p. 171 e¢ seq. 556 SUMMARY OF CURRENT RESEARCHES RELATING TO Figs. 101 and 102 (where in Fig. 101 A is a vertical view, and in Fig. 102 B a sectional view, and C the prism three-fourths full size). He states that this accessory is easily placed in position in the well- hole of the “ Acme” stand, and that doubtless with slight modifica- tions this system of mounting the prism may be applicable to other Microscopes. Provision is made for centering in a lateral direction Fig. 101. Se 2B SSE: GLU by means of the milled head at A. The prism can also be revolved by the milled head shown below so as to use either face, the faces being cut at different angles. Regarding the angles of the prism- faces, he thinks 98°, 41°, and 41°, as suggested by Dr. Woodward, are good ; but that 93°, 47°, and 40°, which he has himself adopted, are especially adapted for the general run of modern wide-apertured objectives. He gives detailed instructions for the use of the apparatus and thinks that it “bids fair to come into general use.” Prisms versus the Hemispherical Lens as Illuminators.—In various catalogues issued by American opticians, references are also made to sundry forms of mounting for the “Woodward” prism. It appears to us that much ingenuity is being wasted in such efforts, for whatever may be the angles of the prism-faces, the hemispherical lens — must necessarily entirely supersede it, having in fact an infinite number of facets through which normal light may reach the common centre. There may of course be cases where a small beam of parallel rays ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 557 directly transmitted by the plane prism-face may be thought to produce the purest effect of oblique illumination; but in our ex- perience wherever oblique light is required for the resolution of strie, &c., the slight condensation of rays produced by the curved surface of the hemispherical lens is no detriment, but rather the contrary, whilst for facility of manipulation the lens is greatly to be preferred. Mounting the hemispherical lens on a plate to be put immediately beneath the slide is not to be commended, for every movement of the slide then carries the illuminator with it, and the direction of the light requires continual readjustment. No better plan of applying the lens has been suggested than that adopted by Tolles and Ross, in which it is mounted to slide or screw into the stage-aperture from beneath. This plan is applicable to nearly all the modern Micro- scopes having mechanical stages. For the Microscopes generally used on the Continent, without mechanical stage-movements, the hemispherical lens may be mounted, as suggested by Professor Abbe, in a disk of metal made to drop into the stage-opening from above so that the plane face is flush with the level of the stage. Radial Tail-pieces—Since the introduction of the Zentmayer swinging tail-piece or swinging substage in 1876, several opticians have carried out the same principle, but instead of the pivot motion of Zentmayer a disk is applied at right angles behind the stage in which a movable zone is fitted to carry the tail-piece. In all the Micro- scopes we have inspected in which this plan is adopted, we remark that the attachment of the tail-piece is so slight as seriously to inter- fere with the firmness of the substage. This is a great inconveni- ence in all manipulations of the substage ; the rackwork, centering- screws, diaphragms, mirror, or whatever may be attached to the tail- piece, cannot be touched whilst the eye is directed through the Microscope, without the flexure of the tail-piece causing the illumina- tion to move from the field of view. Of course this applies only to the use of high powers, but all such Microscopes are supposed to be made specially for high-power work. Electric Light in Microscopy.—Referring to his previous paper on this subject,* Dr. Van Heurck sends us the accompanying Fig. 103, showing the Regnier battery which he has adopted in place of the Tommasi; the sulphate of copper being placed in the small basket at the left-hand side of the cells. The Regnier accumulator is also shown in Fig. 104. Dr. Van Heurck adds that the Regnier battery can be placed in the laboratory of the microscopist, as it does not give off any vapours. It will remain charged for at least a month if sulphate of copper is added as required. Sixty-four Regnier elements (each = 1:07 volts), charging sixteen accumulators, lighted a great part of his house for six weeks. They can be used with only one accumulator, to act as a * See this Journal, ante, pp. 418-20. 558 MMARY OF CUR RENT RESEARCHES R ELATIN G TO Fic. 108. I Mas > Fes ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 559 regulator of the current. If expense is not an object four accumu- lators may be used (requiring sixteen elements), the accumulators thus serving both as regulators and reservoirs, and allowing several lamps to be used at a time. The particular Swan lamps he uses are the ‘‘24-candle” lamps. Still later Dr. Van Heurck says that he is experimenting with some new accumulators of M. de Kabath, which seem likely to give good results. Black Backgrounds.*— Mr. Tuffen West on principle very much dislikes to see objects mounted with an irremovable black back- ground. When it is desirable to view objects as opaque, there are so many other ways of doing this; e.g. the diaphragm, the dark-well, a piece of dead-black paper, cloth, or velvet placed behind the slide. The object can then still be viewed as a transparent object also. Otherwise it is the mounter saying to the observer, “ You shall see my slide as I will, and in no other way.” Micrometrical Measurement by means of Optical Images.t—A paper on this subject was published some time since by Professor Abbe in German, and we at once had it translated with a view to its insertion in this Journal. We must frankly confess, however, our inability to put the paper in proper form for publication here, and as Professor Abbe is much taxed in various ways we have not thought it right to ask him to undertake the matter. We therefore content ourselves with a translation of a German abstract of the article. + “Hi. Abbe has turned his attention to the study of the Microscope as used with a micrometer, and finds that the sources of error belong- ing to the present methods of measurement can be obviated by using ‘telescopic’ systems of lenses instead of the ordinary objective with a finite focal distance. Such a glass is made up of two separate lenses or systems, whose focal planes are turned towards each other and coincide. It has an unlimited focal length, and the focal points lie at an infinite distance; all objects are reproduced with an enlarge- ment which may be determined at will, but is constant; so that this magnification remains independent alike of the distance of the object, that of the image, and of the length of the tube.” Malassez’s Improved Compte-globules.—Professor L. Malassez in 1880 published § a detailed paper on corpuscle-counters in which the various devices of himself, Hayem and Nachet, Gowers and Zeiss were fully referred to with a statement of their respective advantages and disadvantages, and in which he described an improved apparatus suggested by himself. An epitome of the paper by Mrs. Ernest Hart with critical observations has also appeared in English,|| so that it is unnecessary to refer to it otherwise than briefly here. * Journ. Post. Micr. Soc., i. (1882) p. 94. + SB. Jenaisch. Gesell, f. Med. u. Naturw., 1879, p. xi. t Jahresber. (Virchow and Hirsch) for 1879, p. 27. § Arch. de Physiologie, 1880, p. 377. | Quart. Journ, Micr, Sci., xxi. (1881) pp. 132-45 (3 figs.). 560 SUMMARY OF CURRENT RESEARCHES RELATING TO The improved apparatus is shown in Fig. 105. It is made by M. Vérick, and consists of a thick brass slide, having in the centre an © © 2 @® © (9) *71@ @| 6 © S @o ~ ® 6 @|9 © OE Wons tome © 3 5s 0° 4% e 2 9 Cele. @2 © &.|.2 © ~ FOO aperture, into which is fixed a circular glass block about a centimetre in diameter, with its upper surface level with the top of the slide, and ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 561 surrounded by a groove about half the thickness of the slide in depth. Outside this groove are three pointed metal screws equidistant from each other, the elevation of which above the surface of the slide is exactly } mm. Im the centre of the glass block the squares are drawn in which the corpuscles are counted. The sides of these are sly mm., and they are arranged in groups of twenty, as shown in Fig. 106 (x 200). To facilitate lowering the cover-glass so as to be exactly horizontal, M. Malassez devised the frame (Fig. 105) to the underneath part of which the edges of the cover-glass are attached by a little water or saliva. The frame is supported on two arms attached to one flange of Fic. 107. a hinge, the other flange being secured to the slide by a clasping screw. The frame with the cover-glass is raised or lowered by the longer of the two arms, and the operation may be quickly performed. A small spring clip keeps the whole down so that there is no danger of the cover being raised or displaced. Fic. 108. The mixing of the blood is effected in the “ Mélangeur Potain,” shown in Fig. 107, and the whole apparatus, with triangular knife for making incisions, cover-glass, and a bottle of diluting liquid, packs into a small pocket-case 13°5 x 8x 2°5 em. (Fig. 108). Ser. 2.—Vot. II. 2p 562 SUMMARY OF CURRENT RESEARCHES RELATING TO AsBE, E.—The Relation of Aperture and Power in the Microscope. This Journal, ii. (1882) pp. 300-9. Engl. Mech., XX XY. (1882) pp. 374-5. “ Akakia.”—Microscopy—Wide-angle Objectives. Engl, Mech., XXXV. (1882) p. 283. ss Microscope Power. [Reply to “ Antares,” infra, as to the non-increase of aperture of some oil-immersion objectives over the figures shown with Abbe’s Aperto- meter when water is used as the immersion fluid. An oil-immersion, if of only 1:25 N.A., will show that aperture with water, as it is below the maximum 1°33. Substituting oil cannot increase the reading, as the maximum aperture of the lens has been already measured. | Engl. Mech., XXXYV. (1882) pp. 309-10. American Society of Microscopists. [Review of ‘ Proceedings’ of 4th Annual Meeting at Columbus, O.] Amer. Natural., XVI. (1882) pp. 343-6. [Circular of the President, Dr. G. E. Blackham, as to the Elmira Meeting in August 1882, and Letters from him and Dr. Up de Graff. Also circular as to proposed Quarterly Journal of Microscopy, &c.] The Microscope, II. (1882) pp. 47-8, 85-7, 94. “« Antares.” —Microscope Power. [Partial statement . . . of the details of magnifying power provided by an ordinary well-furnished instrument of full size.” ] Engl. Mech., XXXYV. (1882) pp. 261-2. ull The Apertometer—Lantern Objectives. [Reply approving of the explanation given in “ Akakia’s” letter, supra, and account of further experiments with objectives. Also remarks on the Apertometer and Aperture-measuring. A query to Mr. Shrubsole as to Lantern Objectives. ] Engl. Mech., XXXY. (1882) p. 429. Baur, W. M.—On Recent Improvements in Microscopy. [Deals with objectives, illuminating apparatus, stands, stages, swinging tail-pieces, this Journal, &c.] Southern Science Record, Il. (1882) pp. 75-80. BEALE’s (L. 8.) Microscope in Medicine. 4th ed. (Review, with extended remarks on the germ theory of disease. ] Amer, Natural., XVI. (1882) pp. 500-4. Bowman, F. H.—The Structure of the Cotton Fibre in its relation to Technical Applications. 2nd ed. [Contains description of Microscope and Micrometers, pp. 7-14, and note on the “ Limit of Microscopic Vision,” p. 157.] 8vo, Manchester, 1882, xvi. and 211 pp. (5 figs. and 12 pls.). Boys, C. V.—Measurement of Curvature and Refractive Index. Engl. Mech., XXXV. (1882) pp. 469-71, from ‘ Philosophical Magazine.’ Brappury, W.—The Achromatic Object-Glass. I-VI. [Deals with “the theoretical conditions that must be satisfied in the formation of an object-glass.’’] Engl. Mech., XX XV. (1882) pp. 297-8, 344, 371-2, 393, 418-9, 440-1. Brirrain, T.—The Beginnings of Microscopic Study. [Brief general history of the simple and compound Microscope and Leuwenhoeck’s observations. j Field Naturalist, I. (1882) pp. 7-8. Buttocu, W. H.—Iris Diaphragm for Use above an Objective. [Claims to have been the first to introduce it, and refers to his Catalogue of 1878. J. W. Sidle subsequently writes referring to Dr. Royston-Pigott’s previous description of such an apparatus. | Amer. Mon. Micr. Journ., III. (1882) pp. 99, 117-8. Butiocu’s (W. H.) Apparatus for Measuring the Magnifying Power of Oculars. [Post.] Amer. Mon. Micr, Journ., III. (1882) pp. 103-4 (1 fig.). The Microscope, Il, (1882) pp. 83-4. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 563 Butiocn’s (W. H.) Improvements in Microscopes. [Supra, p. 554.) Amer, Mon. Mier. Journ., III. (1882) p. 97. CHARDONNET, de —.—Sur la transparence actinique des verres d’optique. (On the Actinic Transparency of Optical Glass.) Comptes Rendus, XCIV. (1882) pp. 1468-70. Curvatier, A.—L’Etudiant Micrographe. Traité théorique et pratique du Microscope et des préparations. (The Microscopical Student. Theoretical and _ practical treatise on the Microscope and preparations.) 3rd ed. 8vo, Paris, 1882, xvi. and 591 pp. (179 figs., 7 plates, and portrait). Coz, A. C.—Studies in Microscopical Science. Vol. I. No. 1 (pp. 1-8).—Yellow Fibro-Cartilage—Long. Vert. Sec. Pinna of Ear of Cow, double-stained in logwood and eosin. Plate x 333. No. 2 (pp. 9-20).—Trans. Sec. Dicotyledonous Stem — Copper Beech (Fagus cuprea), stained carmine and iodine green. Plate x 25. No. 3 (pp. 21-8).—Human Bone—Trans. Sec. Compact Tissue of Shaft of a Long Bone (Clavicle). Plate x 50. : No. 4 (pp. 29-32).—Trans. Sec. Monocotyledonous Stem — Umbrella Plant (Cyperus alternifolius)—Closed Fibro-Vascular Bundle, stained carmine and iodine green. Plate x 400. No. 5 (pp. 33-40).—Human Skin — Vert. Sec. Sole of Foot, stained carmine and sulph-indigotate of soda. Plate x 65. No. 6 (pp. 41-8).—Section of Pikrite (Inchcolm, Firth of Forth). Plate x 25. No. 6a (pp. 49-64).—Same continued with Analytical Chart. No. 7 (pp. 65-74).—Trausverse Section of Spinal Cord of Cat—dorsal region. Plate x 20. No. 8 (pp. 75-78).—Transverse Section of underground portion of Rachis of Frond of Bracken Fern (Pteris aquilina). Plate x 333. No. 9 (pp. 79-86),—Vertical Section of Human Liver, stained logwood. Plate x 233°3. No. 10 (pp. 87-92).—Transverse Section of Thallus of Fucus vesiculosus with Antheridia and Oogonia. Plate x 154. No. 11 (pp. 93-102).—Vertical Section of Liver of Cat, injected (hepatic vein red, portal vein blue). Plate x 50. No. 12 (pp. 103-8).—Transverse Vertical Section of a Leaf (Rhododen:Jron ponticuin), stained logwood. Plate x 333. Reviewed in Journ. of Sci., [V. (1882) pp. 374-5. Sci.-Gossip, 1882, pp. 138, 160, and 186. Knowledge, I. (1882) p. 609. Nature, XX VI. (1882) p. 89. North. Microscopist, II. (1882) pp. 163 and 193. The Microscope, IL. (1882) p. 93. Cox, J. D.—Measurement of Microscopic Aperture. [Abstr. of article, ante, p. 422.] Amer, Natural., XVI. (1882) pp. 532-3. Crisp, F.—Notes sur l’Ouverture, la vision microscopique et la valeur des objectifs & immersion & grand angle. (Notes on Aperture, Microscopical Vision, and the value of wide-angled Immersion Objectives)—contd, . [Transl. of paper I. (1881) pp. 303-60. ] Journ. de Microgr., VI. (1882) pp. 246-51 (2 figs.), 299-303 (6 figs.). CrumepaucH, J. W.—The History of the Microscope and its Accessories, I. I. The Microscope, II. (1882) pp. 33-8, 65-9. Davis, G. E.—Practical Microscopy, 2nd ed. 8vo, London, 1882, viil. and 335 pp. (258 figs. and 1 pl.). Ist ed. reviewed in Amer. Natural., XVI. (1882) pp. 432-3. Nature, XXV. (1882) pp. 502-3. Sci.-Gossip, 1882, p. 112. 3 “ The Limiting Diaphragm or Aperture Shutter. [Comment on the statement, ante p. 407, that objectives of wide aperture cannot be made to do duty as narrow-angled ones also, so as to dispense with two classes of objectives. ] North, Microscopist, II. (1882) p. 194. 2Pe2 e 564 SUMMARY OF CURRENT RESEARCHES RELATING TO Desy, J., and F. Kirron.—A Bibliography of the Microscope and Micro- graphic Studies, being a catalogue of books and papers in the library of J. Deby. Part III. The Diatomacee. (Part 3 in advance of Parts 1 and 2.) 8yvo, London (privately printed) 1882, 67 pp. Dieret, L.—[Review of Dr. H. Van Heurck’s paper on homogeneous-immersion objectives and finids (cf. this Journal, ante, p. 264), preceded by a statement of his reasons for objecting, in opposition to Dr. Van Heurck, to correction-adjust- ments with such objectives. See also supra, p. 551. Bot. Centralbl., X. (1882) pp. 222-5. Epuunps, J.—See Wenham, infra. ENGELMANN, T. W.—Appareil Microspectral (Microspectroscopie Apparatus). [For experiments on the disengagement of oxygen by vegetable cells, post. ] Rev. Internat, Sci. Biol., TX. (1882) pp. 465-7. Fa.LkinpurcG, W. S.—Hints to Amateur Microscopists. [How to make a bull’s-eye condenser from an old-fashioned bull’s-eye watch-glass filled with glycerine and closed with plate glass. | Amer. Mon. Wicr. Journ., 111. (1882) p. 92. F.R.M.S. and “ Another F.R.M.S.”—See Wenhan, infra. Go.tzscu, H.—Binoculares Mikroskop (Binocular Microscope). [Post.] Zeitschr. f. Instrumentenk., Il. (1882) pp. 225-6 (1 fig.), from Carl’s Repertorium fiir Experimental-physik, xviii. (1882) pp. 27-32. GUILLEMARE, —.—See Lutz, EH. - GunpLacH, E.—Oblique Illumination, with a special consideration of the capabilities of Immersion Condensers, and a note on Symmetricai Illumination. [ Post. ] Amer. Mon. Micr. Journ., III. (1882) pp. 85-8 (1 fig.). Haut, L. B—An Eye-protector for use with the Monocular Microscope. [Post.] The Microscope, 11. (1882) pp. 88-90, from Vedical and Surgical Reports. Hevrcg, H. Van.—The Electric Light applied to Microscopical Research. (Transl. of paper, ante, p. 418.] North. Wicroscopist, 11. (1882) pp. 141-7 (1 fig.). See also Rev. Wycologique (1882) p. 199. Hick, —.— Microscopic Tank. {Inquiry how to make a small tank for microscopic use (10 x 8 x 2), opaque ends and bottom.] [Reply by J. A. Ollard—* crystallized dishes of about 7 inches diameter.” ] Sci.-Gossip, 1882, pp. 142 and 160. Hincenporr, F.—Apparat fiir mikroskopische geometrische Zeichnungen. (Apparatus for Microscopical Geometrical Drawings.) SB. Gesell. Nat. Fr. Berlin, 1882, pp. 58-60. Hitcncock, R.—Numerical Aperture. [« A plain statement of what numerical aperture is.”] Amer, Mon. Micr. Journ., IIl. (1882) pp. 95-6. si 5, The Microscope Trade. [Protest against underselling.] Amer. Mon, Mier. Journ., II. (1882) p. 97. x » Newspaper Science. [Quotations of “ conglomerations of error and deliberate falsehood” in an article in the Mechanical News on the ‘ Power of the Microscope.’] Amer, Mon. Micr. Journ., TIL. (1882) p. 98. J., T. R.—What is the meaning of the sign x? [Reply to E. Holmes, ante, p. 423, and insisting upon the correctness of his former view. ‘‘The idea of amplification alone does not cover the meaning of the sign x as used microscopically . . . . not algebrai- cally or mechanically.”} Sci.-Gossip, 1882, p. 159. Kirron, F.—See Deby, J. we ee ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 565 Lancaster, W. J.—See Sturt, T. J. LANDsBERG, C.—Ueber den Antheil der Proving Hannover an der Entwick- lung der Feinmechanik. (On the Share of the Province of Hanover in the Development of Fine Mechanical Work.) [The pages noted contain a correction of Harting’s statement in ‘ Das Mikroskop,’ that S. G. Hoffmann (who made Microscopes in the second half of the 18th century) was a Hanoverian—he in fact lived in Leipzig. 2 ek eR f. Optik u. Mech., III. (1882) pp. 159-60 (foot-note). Lossner, O. M.—Telemikroskop (Telemicroscope). [Abstract of Patent—see ante, p. 424 and supra, p. 547.] Centr.-Ztg. f. Opt. u. Mech., III. (1882) p. 108. Lovett, E.—Dark-ground Illumination. {Incorrect heading—relates to white or porcelain backgrounds and slips of glass to be put under the slide, either of pale blue (for modifying the light), opal porcelain or china (for viewing dark objects as opaque, such as seeds), dull varnished on one side (for most opaque objects), or ground glass (for Foraminifera). | Journ. Post, Micr. Soc., I. (1882) pp. 94-5. Lutz, E.—Microscope scolaire (School Microscope). [Designed by Professor Guillemare, post. ] Journ, de Microgr., VI. (1882) pp. 233-5 (1 fig.). See also Rev. Mycologique, IV. (1882) p. 199. M‘A.uister’s (T. H.) Protector for Objectives. [Copy of the Richards’ Protector. ] Amer. Natural., XVI. (1882) p. 618 (2 figs.). Merz, 8.—Ueber Dispersions-Verhaltnisse optischer Glaser. (On the Dis- persion Relations of Optical Glass.) [Discussion of the best combinations of flint and crown glass to remove the secondary spectrum. } Zeitschr. f. Instrumentenk., 11. (1882) pp. 176-80. Microscope by Culpepper and Scarlet, formerly in the possession of Sir A. Lever, exhibited and briefly described at meeting of Manchester Microscopical Society. North, Microscopist, IL. (1882) p. 189, Moorsz, A. Y.—Something about Objectives. [Post.] The Microscope, II. (1882) pp. 8-11. Moss, J. M.—See Wenham, infra. Mounting Micro. Lens. [Directioas by W. J. Lancaster. See also ante, p. 424.] Engl. Mech., XX XV. (1882) p. 335. Mcnro, J. M. H.—Battery power for Swan Lamps. [40 Grove cells were found to be necessary for 3 Swan lamps of 25 to 50 candle power—8 to 10 cells will probably be sufficient for lamps of 5 candle power. ] North. Microscopist, II. (1882) pp. 150-1, from The Vechanical World. Netson, E. M.—See Wenham, infra. es a Tuberculosis. [Contains reference to a 3.-inch oil-immersion objective 1:38 N.A. “ speci- ally constructed for me by Powell and Lealand for the purpose of investigating micro-organisms, and may fairly rank as the greatest achievement in the science of microscopical optics ”—also to a fine adjustment to the substage of the Microscope which * will be found most bck by those engaged in observations with wide-angled high powers.” Engl, Mech., XXXYV. (1882) p. 378 (2 figs.). OxuarD, J. A.—See Hickin. i » Tadpole Slides. [Description of Schultze’s, ante, p. 110, and of the following. “Forma groove or cell on an ordinary slip of glass with folded blotting-paper 566 SUMMARY OF CURRENT RESEARCHES RELATING TO saturated with water; lay the tadpole in between on the glass, tail flat ; cover the body over with saturated blotting-paper, the tail Gf necessary) with thin glass. Keep the whole well saturated, and the tadpole will live for many exhibitions.’”] Engl. Mech., XX XY. (1882) p. 284 (1 fig.). Ouuarp, J. AA—The Microscopist’s Companion. [Description of a support for pocket lens with forceps and Forrest’s Compressorium. | Engl. Mech., XXXYV. (1882) p. 330 (2 figs.). PELLETAN, J.—[Announcement of an intended publication of papers on (1) The theory of the Microscope ; (2) The theory, construction, and use of Objectives ; (8) Microscopes. ] Journ, de Microgr., VI. (1882) p. 206. See also Rev. Mycologique, IV. (1882) p. 198. Postal Microscopical Society’s Journal. [Notice of Nos. 1 and 2.] Amer, Natural., XVI. (1882) p. 533. Sci.-Gossip, 1882, p. 186. President’s Address. [Abstract in part and note, ‘‘ As a whole it is one of the best, most clear, sensible, and intelligible presidential addresses that it has been our good fortune to read for some time.’’] Amer. Mon, Micr. Journ., III. (1882) pp. 106-11, 116. Proctor, R. A.—The Eyes of Science. [Deals principally with the extension of the power of human vision by * photographie processes and methods—brief reference to the Telescope, Microscope, Spectroscope, &e.] Knowledge, II. (1882) pp. 54-5. Reppinc, T. B.—The Microscope : its revelations, with some of their bearings upon Christian Evidences. Acton Lectures. 8vo, Indianapolis, 1881, pp. 129-48. Reynier, E.—An Electric Battery for the Laboratory and Dvwelling- house. [Translation from La Nature, describing the battery mentioned ante, p. 418-9. ] : North. Microscopist, 11. (1882) pp. 147-50. RovumEGtERE, C.—Le Microscope populaire en Amérique. (Popular Microscopy in America.) [Note as to the rapid progress made in the New World by micrography, with special reference to the Michigan University and Ann Arbor Soirées. | $ Rev. Mycologique, IV. (1882) pp. 199-200, SrrBert, W.—Anwendung des Tépler’schen Schlieren-Apparates auf Mikro- skope. (Use of the Tépler Apparatus in Microscopy.) [ Post. ] Zeitsohr. f. Instrumentenk., 11. 1882) pp. 92-6 (3 figs.), Abstr. in Centr.-Zig. f. Opt. u. Mech., TIL. (1882) p. 105 (2 figs.). Sipiz, J. W.—See Bulloch, W. H. Srpix’s Iris Diaphragms and “ Acme” Stands. [Brief description. ] North. Microscopist, II. (1882) pp. 190-1. SrEINHEIL’s Eye-pieces. See this Journal, supra, p. 551. Engl. Mech.. XX XV. (1882) p. 458. Sroxzs, A. W.—A Tadpole Slide. [Objections to the plan of ‘‘ Volvox ” (ante, p, 438), as it prevents the use of a higher power than the 4 in.; it never ensures the tail lying flat from end to end, and the use of chloroform retards tle circulation. Description of his own Tadpole Slide (ante, p. 110).] Engl. Mech.. XX XV. (1882) pp. 237-8 (1 fig.). (ts Se a ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 567 StoweEtt, C. H. & L. R.—Editorial Notes. [As to the first vol. of ‘ The Microscope "—Bausch and Lomb’s “ 3 homo- geneous,” homogeneous-immersion condenser, mechanical finger and turntable, &e.—Arnold’s Photomicrographs—Teichmann’s Hemin Crystals—Prof. A. Y. Moore’s Resolution of “ Amphipleura pellucida with a 2 homogeneous by Central Sunlight” — Ward’s Pigeon-post Films—&e.] The Microscope, II. (1882) pp. 18-20. [Elmira Meeting of the American Society of Microscopists—&c. ] The Microscope, II. (1882) pp. 50-4, Stvurt, T. J.—Microscopic. [As to using a bi-concave spectacle lens fitted to the draw-tube for table purposes, so that “‘a 2 in. can be used to magnify to the same extent as a 3 in.”—also further query by “ Handy-Man,” and reply by W. J. Lancaster. ] Eng!. Mech., XX XV. (1882) pp. 282-3, 339, 385. Tuoms, W. A., Election of. Amer, Natural., XVI. (1882) p. 621. Wate, G.—See Wenhan, infra. Weap, C. K.—Studies with Micrometers. [(1) Results of comparisons of Rogers’ Micrometers and Fasoldt’s test- plates. (2) On the effect of the cover-correction in changing the magnifying power. (3) Measuring the thickness of cover-glasses by the correction-collar, post. The Microscope, II. (1882) pp. 69-73. Wenuan’s New Microscope. [Further letters by F. H. Wenham, (2) J. M. Moss, Dr. J. Edmunds, and * Another F.R.MS.,” “F.R.MS.,” G. Wale, aud E. M. Nelson, as to the priority of design.] Engl. Mech., XX XV. (1882) pp. 282, 309, 330, 356, 356-7. Wicanb, O.—Verbessertes Skioptikon (Improved Sciopticon). [Post.] Centr.-Zig. f. Opt. u. Mech., III. (1882) pp. 101-2 (1 fig.). Wooster, W. H.—On an Impromptu Bramhall Reflector. (The mirror removed from the Microscope and placed on the stage with the slide on it, condensing the light with the condenser. ] Journ, Micr, Soc. Victoria, I. (1882) pp. 100-1, Zencer, C. V.—Sur une nouvelle combinaison des lentilles du Microscope. (Qn a New Combination of Microscope Lenses.) [Supra, p. 551.] Comptes Rendus, XCIY. (1882) p. 1542, 8. Collecting, Mounting and Examining Objects, &c. Cutting and Mounting Microscopical Sections.*—Mr. A. G. Bourne describes some modifications of older processes, which he considers constitute the latest stage of development of the section- cutter’s art. Hardening.— Any of the ordinary hardening methods may be used, but it is essential that all trace of acid should be removed in order to obtain good staining results. Corrosive sublimate is an exceedingly useful hardening reagent, and tissue treated with it stains as readily as if treated with alcohol only. The solution used is a concentrated one. The fresh tissue or living animal is placed in it for fifteen to thirty minutes, according to its size; it is then washed in water and transferred to alcohol of 50 per cent.—a large relative bulk of this must be used, and the tissue well permeated by it, otherwise some * Quart. Journ. Micr. Sci., xxii. (1882) pp. 334-7, 568 SUMMARY OF CURRENT RESEARCHES RELATING TO corrosive sublimate is left in the tissue and is thrown down in needles when strong alcohol is added. After 24 hours the tissue is trans- ferred to alcohol of 70 per cent., and after 24 hours to alcohol of 90 per cent., and then to absolute alcohol. With large pieces of dense tissue this should be changed once or twice. After two or three days the tissue is ready for staining, If time is an object, and no acid has been used in the hardening, the tissue may be transferred directly from alcohol of 70 per cent. to the staining fluid; but it is advisable, and in the case of delicate tissues necessary, to complete the hardening process before staining. Staining.—Grenacher’s alcoholic borax carmine is used. Pure carmine (2°5 per cent.) is added to the solution of borax (4 per cent.), in water ; this is allowed to stand for two or three days, and occasion- ally stirred—the greater part of the carmine will dissolve. To this solution is added an equal bulk of alcohol of 70 per cent. This mixture must stand for a week and then be filtered, when it is ready for use. If on keeping more carmine is deposited, it should be refiltered. The tissue is placed in this solution, and allowed to remain one, two, or three days according to its size; it is hardly possible to over- stain, and there is sufficient alcohol in the solution to prevent injury to any but the most delicate tissues. For such tissues a solution can be prepared containing more alcohol, but of course less carmine. The tissue when removed from the staining fluid is placed in alcohol of 70 per cent., acidulated with hydrochlorie aeid (8 to 6 drops of the acid to 100 cc. of spirit). This dissolves out all excess of carmine and fixes the rest. The tissue, 2 dark purplish-red when taken out of the borax carmine, should be left in the acidulated alcohol till it aequires a bright transparent look (3 to 6 hours), it may then be transferred to absolute alcohol and afterwards to tur- pentine. When thoroughly permeated with this latter (the time necessary varying as the size of the lump of tissue) it is ready for imbedding. Imbedding.—This is: done in paraffin, and it is exceedingly im- portant to obtain a suitable paraffin. It shouid melt at 100° or 115° F. Paraffin of various melting points should be kept in the laboratory ; they may be purchased at the dealers. The tendency to curl up on the part of the section may be reduced to a minimum by obtaining a paraffin of the proper consistency, but this seems to vary according to the temperature of the room in which the sections are cut. The paraffin must be melted in a small covered vessel in a water- oven, great care being taken to keep it in a dry atmosphere. The temperature in the oven should never rise more than two or three degrees above the melting point of the paraffin used. When the paraffin is melted the tissue is removed from the tur- pentine and placed in it, and this must be kept at its melting point for some hours until the tissue is thoroughly permeated ; it may then be poured into a paper trough, watch-glass, or any other vessel, and allowed to cool. = ae ZOOLOGY AND BOTANY, MICROSCOPY, ETC. _ 569 Cutting.—There are two forms of microtome suitable for cutting sections in series. In one the tissue is raised directly by a fine screw, and the sections cut with an ordinary razor: in the other form, now so largely used, the tissue in its holder is moved up an inclined plane, and the sections cut with a large knife which works backwards and forwards in a horizontal slot running parallel with the inclined . plane. In both cases the machine is fixed to the table or heavy enough to remain steady, so that while the razor is worked with one hand the other hand is at liberty to hold a little paper spatula—a small piece of paper run on at the end of a small scalpel—to prevent the sections curling. The paraffin block is pared down to the smallest size possible, and, as the razor is drawn along, the edge, which com- mences to curl, is caught by the paper and prevented from so doing; the section is then transferred to the slide. Preparation of the Slide.—The slide is smeared with a strong solution of shellac in anhydrous creosote. Care must be taken to have as little as possible on the slide. By this method the sections are stuck to the slide, thereby saving the most delicate objects from falling to pieces after the paraffin is removed, and enabling one to mount numerous sections on one slide. The importance and value of this treatment cannot be over-estimated. It enables one to mount with absolute certainty whole sections of the most friable objects, such as an insect, without a single fragment of the section becoming displaced. Mounting.—The slide bearing the sections is now placed in a water-oven or on a tin box containing water at a temperature two or three degrees above the melting point of the paraffin used. The slide is left here for at least half an hour. The object of this warming is twofold, to evaporate the creosote and to melt the paraffin. The slide is now taken up, and while the paraffin is still molten is flooded with turpentine dropped from a small pipette. This dis- solves melted paraffin instantaneously, and precipitates the shellac fastening the sections to the slide. The turpentine is allowed to flow off, and replaced by new until all the paraffin is removed. The slide is then allowed to drain, the edges wiped, and the cover-glass put on. The Canada balsam, which should be very fluid, is placed on the under surface of the cover-glass; this is turned over and quickly lowered. The balsam dissolves the shellac, and if the cover-glass is not put on very quickly the sections may shift or delicate sections come to pieces and float off the slide. It being necessary to use the balsam in such a fluid condition, and a certain amount of turpentine always remaining upon the slide, the slides should be looked over the next day and more balsam added at the edge of the cover-glass if necessary. ‘These methods, especially that of fastening the sections to the slide with shellac, although suggested and elaborated by zoo- logists for the purpose of mounting serial preparations, will, no doubt, come into very general use in ordinary histology for such tissues as placenta or spleen where very thin sections have always been found liable to fall to pieces, and the most important pieces to fall out and be lost. 570 SUMMARY OF CURRENT RESEARCHES RELATING TO Preparing Blastoderm of the Chick —C. Koller,* who has taken up this subject in order to decide some disputed points in the embry- ology of the chick, thus describes the method by which his prepara- tions were made. The egg was subjected to the hatching method recommended by Kélliker. At the proper time it was opened and its contents carefully transferred to a glass; as much of the albumen as pos- sible being removed by the fingers or otherwise. In order to keep a note of the exact direction in which it was wished to take the sections, it was generally found necessary to make an indication on the egg while still fresh, as in the earlier stages the appearances in the surface of the yolk are rendered indistinct by the process of hardening; to this end, Koller has been accustomed to insert with forceps a small triangular pointed slip of paper into the yolk im- mediately behind the germinal disk in such a way that it indicates the extreme posterior margin of the blastoderm, and lies at the same time in the median plane of the future embryo. The yolk is now submitted for twenty-four hours to the action of a +, per cent. solu- tion of chromic acid, and then for another twenty-four hours to one of 1 per cent., and thus increasing the strength daily up to 4 per cent. If the yolk is sufficiently hardened, the segment on which the blasto- derm lies, together with the central mass, is detached with a fine scalpel and immersed in distilled water for twenty-four hours to remove the superfluous chromic acid. The yolk-membrane may he very readily removed from the hardened germ without injuring the latter. The blastoderm is stained entire with weak ammoniacal carmine (length of staining twelve to twenty-four hours), then washed by twenty-four hours’ immersion in distilled water and placed in absolute alcohol. It is ready for cutting in from one to two days. After lying for a few minutes in oil of cloves it is imbedded in a mixture of wax and oil. Sections are made by hand, using turpentine to moisten the object. Preparing Embryos of Insects.t—In a paper on the embryonic development of the Bombycide, Dr. §. Selvatico describes the methods he has made use of both for the preparation of entire embryos and for sections. The species employed were Bombyx mori, Atiacus Mylitta, and Saturnia py7t. The eggs are first coagulated by plunging them in water at 75° C. With a pair of fine-pointed forceps a small piece is removed from the shell, in the case of Bombyx, without disturbing the underlying parts. With a little care this is easily done, because on the eggs becoming cold their contents are somewhat contracted and do not teuch the shell. In the case of Attacus and Saturnia the eggs have a harder shell but are larger, and a razor was employed by the author. They are then hardened by leaving them for twelve hours in a -002 per cent. solution of chromic acid, and for twelve hours more in a ‘005 solution. Then with a little care the shell can be easily * Arch. Miky. Anat., xx. (1881) pp. 181-2. + Journ, de Microgr., vi. (1882) pp. 220-1, ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 571 removed by employing the forceps or cutting it round with a razor. The entire contents having been removed the egg is freed from chromic acid by leaving it in 30 per cent. alcohol for a day, the alcohol being renewed until it is no longer coloured yellow. For staining, the egg is placed in picrocarmine for twenty-four hours and washed in 30 per cent. alcohol to remove the picric acid. When it has been well washed it may be kept in 30 per cent. alcohol until sections are required. Previous to cutting sections the egg should be placed in absolute alcohol for half an hour, and then for a few moments in essence of bergamot. Dry and imbed in a mixture of 4 parts of spermaceti and 1 of cacao butter, to which is added, according to the temperature, some drops of castor-oil. The knife should be moistened with olive- oil and each section washed with a mixture of 4 parts of oil of turpen- tine and 1 of creosote to dissolve the imbedding substance surround- ing the section. Mount in Canada balsam. To preserve the embryo entire, the shell is to be removed as above described, after coagulation. The egg is then placed in a drop of water on the stage, and with a low power the embryo is extracted from the vitellus. It is cleaned as much as possible, so that no portion of the vitellus adheres to it, and mounted in glycerinated gelatine, previously coloured with methyl-green. By this method the embryo takes from the gelatine an excess of colour, and is thus stained after the preparation is made. If it is coloured first and then placed in colourless gelatine it will always lose colour (sometimes completely) if the gelatine is only a little greater in volume than the embryo. Collecting, Staining, and Fhotographing Bacteria.*—Dr. G. M. Sternberg in “a contribution to the study of the bacterial organisms commonly found upon exposed mucous surfaces and in the alimentary canal of healthy individuals ” (which contains much interesting matter), states that he has found the following to be the most satisfactory method of collecting bacteria for examination with high powers and for photography. The slightest possible smear of the material to be examined is allowed to dry upon a thin glass cover, and to secure a sufficiently uniform layer, it is usually best to spread it while moist with the end of a glass slide. Material is obtained from the mouth by scrap- ing the surface of the tongue, or of the teeth, with a clean instrument ; from the female vagina by a speculum or: digital examination; and from the male urethra, by applying a thin glass cover directly to the moist mucous membrane at the extremity of the canal. A five-cent bottle of aniline violet ink furnishes an ample supply of staining fluid of the best quality. Two or three drops of this - placed upon the thin cover will very quickly—one to three minutes— give the tacterial organisms attached to its surface a deep violet colour. The cover is then to be washed by a gentle stream of pure water, and is ready for immediate examination, or may be mounted * Stud. from the Biol. Lab. Johns Hopkins Univ., ii. (1882) pp. 157-81 (19 photomicrographs). 572 SUMMARY OF CURRENT RESEARCHES RELATING TO for permanent preservation over a shallow cell containing a solution of potassium acetate (Koch’s method), carbolic acid water (2-5 per cent.), camphor water, or simply distilled water. To make satisfactory photographs of the smallest bacteria, it is necessary to use a staining fluid which will give a stronger photo- graphic contrast, as the violet is transparent for the actinic rays. For this purpose aniline brown (recommended by Koch) may be em- ployed, or iodine solution (iodine 2-5 grains, potassium iodide q. s. to dissolve, distilled water 100 grains). A recent writer (Soubbotine *) advises the use of osmic acid as a fixing solution to be used in advance of staining. This is doubtless desirable when specimens of blood or thin sections of tissue containing bacteria are to be examined, as the normal histological elements are better shown, but the method possesses no special advantages so far as the demonstration of vegetable organisms is concerned. It must be remembered that aniline solutions often contain a granular precipitate which might be mistaken by a novice for deeply stained micrococci. Ehrlich’s Method of Exhibiting the Bacteria of Tuberculosis,t— Dr. Ehrlich, Prof. Koch’s assistant, has lately explained { a new method of preparing tuberculous bacteria, which is a great improve- ment on the original process of Koch. It renders the demonstration much easier, and its results are so certain, that it may be applied to establish the diagnosis of the disease in doubtful cases. The pre- parations made according to the method recommended by Koch in his first paper (i.e. double staining by alkaline methylene-blue and vesuvin §) have left doubts in the minds of some observers, which they could not have had if they had seen the preparations obtained by Ehrlich’s process which Koch himself has now adopted in prefer- ence to any other. Tuberculous bacteria as well as all the micro-organisms, bacteria, or micrococci, have a great affinity for aniline colours, and are strongly stained by them. Koch’s researches have shown that the bacteria of tuberculosis have special and characteristic properties, and that their cellular membrane is very easily penetrated by alkalies. It is upon this experimental fact that Koch based his ingenious method, which consists essentially in impregnation by an aniline colour, rendered alkaline by the addition of a small quantity of caustic potash. But this alkali exercises a modifying action on the different histological elements and on the bacteria themselves. Under its influence the albuminoid corpuscles swell to excess, and the coagulated layers of morbid matter are easily detached from the cover-glasses. Ehrlich, therefore, sought for another base, acting in a less powerful manner, and found it in phenylamine or aniline. Other alkaloids, perhaps even vegetable alkaloids, which can be transformed into colouring matters by means of various reagents, might be equally useful. * Arch. de Phys., viii. p. 479. + Bull. Soc. Belg. Micr., vii. (1882) pp. exvii—cxxii. { See Berl. Klin. Wochenschrift, 6th May, 1882. § Cf. this Journal, ante, pp. 385-8. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 573 The following is Dr. Ehrlich’s method of procedure, which does not present any technical difficulty, and does not require more than an hour to make a dozen preparations. By means of a dissecting needle a particle of expectorated matter, about the size of a pin’s head, is taken up and spread between two cover-glasses, * in two exceedingly thin layers on each. The cover-glasses are then separated by sliding one on the other, and left to dry protected from the dust. After a few minutes they are dry, and the fixing of the albuminoids and mucin is proceeded with. For this they can be warmed for an hour at 100° or 120° C., or which is simpler, rapidly passed four or five times through the flame of a spirit-lamp. To colour the prepara- tions a saturated solution of phenylamine is to be made in distilled water, by shaking with the water the excess of aniline which floats on it, and carefully filtering the whole. To the transparent liquid thus obtained add, drop by drop, a saturated alcoholic solution of fuchsine or methyl-violet until a slight opalescence is produced. The preparation should not be immersed in the colouring bath, but be placed in such a manner as to float on it, and to have the surface which is covered with the tuberculous matter in contact with the liquid. After a quarter to half an hour the staining is complete. If examined in this condition it is seen that the preparation is of such an intense colour that it is impossible to distinguish its elements, and Ehrlich happily thought of trying to decolorize it by means of a strong acid ; colourless salts of aniline are then formed, which are very soluble in water and disappear by washing with distilled water. The bacteria, not being penetrated by the acids, preserve their colour. In order to secure that they alone shall be coloured, therefore, it is only necessary to immerse the cover-glasses in nitric acid diluted with twice its volume of water. Nitrous vapours are at once disengaged, and the preparation becomes absolutely colourless in a few seconds. Under the Microscope the bacteria are seen to be very clearly coloured red or violet; but by reason of their extreme delicacy they often escape the eye and require the most accurate focussing. It is therefore better to study them in prepara- tions which have been slightly coloured blue or green (when fuchsine has been used for the first bath), or yellow (when methyl-violet has been used). They are afterwards mounted in Canada balsam in the usual way. The advantages of Ehrlich’s method are summed up by Dr. E. Van Ermengem as follows :—I1st. The aniline alters the form of the histological elements much less than Koch’s solution of potash. 2nd. The process is much quicker, and does not occupy more than an hour. 3rd. Its principal advantage is to produce a more intense staining of the bacteria, so that they appear larger, and can be recognized with a lower power, even with 250 diameters. ‘A question of the highest interest from a medical point of view * Ehrlich chooses cover-glasses whose thickness is appropriate to the objectives to be employed; those from 0°10 to 0°12 mm. he considers the most suitable. + The water dissolves about one part in thirty-one at the ordinary tempera- ture, 12° C, 574 SUMMARY OF CURRENT RESEARCHES RELATING TO has been raised by Ehrlich with reference to his method. The pro- perties which the membranous envelope of the bacteria of tuberculosis seems to possess, prove that the sole disinfectants or antiseptics which can be used to combat this disease, by acting on the bacteria, should be alkalies and not acids, which have hitherto been employed for this purpose. At the May meeting of the “Société Belge de Microscopie,” Dr. Van Ermengem exhibited a series of preparations of tuberculous bacteria obtained from expectorated matter from five patients suffering” from pulmonary phthisis of the second and third degree. In each of these cases a few particles of the sputa sufficed to give at least one preparation in which the characteristic bacilli were found. The first series of preparations were made according to Koch’s method. The bacteria were few and difficult to find. They were feebly coloured (a pale blue), and were very small. ‘To show them clearly a very bright light, obtained by means of an immersion con- denser, and the use of a good immersion objective were necessary (1080 diameters). The second series were partly made by Ehrlich’s process. The bacteria were coloured a bright red by fuchsine, the rest of the pre- paration being completely colourless. In one of the preparations the typical bacteria were very numerous, in groups numbering from four to eight within large cells, or disseminated in pairs here and there, and it was not difficult to recognize the spores: often also they were placed end to end in pairs. The organisms corresponded well with the description given by Koch, and were perfectly recognizable without a condenser and without a high power (750 to 800 diameters.) A few good preparations were also shown in which the ground had been coloured blue. The bacteria were more easily found than in the others, and stood out clearly by their fine red colour from the rest of the preparation (450 diameters). — Specimens of these bacteria prepared by Koch (on his old method) were exhibited by Mr. Watson Cheyne and Mr. E. M. Nelson at the two soirées of the Royal Society on the 10th May and 21st June, and also at that of the College of Physicians, and attracted consider- able attention, not only from the interest which attached to Koch's discovery, but also for the excellent way in which they were shown. Preserving Infusoria and Amcebe.*—E. Korschelt refers to the method described by M. Certes for colouring and preserving Infu- soria,t in regard to which O. Biitschli in his abstract of the paper expressed a hope that it would be possible to find a more suitable pre- serving method as he could not place reliance on preservation in glycerine. The author considers that the following method (which he devised without knowing that of M. Certes) will enable prepara- tions to be made which leave nothing to be desired in regard to durability. The water in which the Infusoria are placed upon the slide must * Zool. Anzeig., v. (1882) pp. 217-9. + See this Journal, ii. (1879) p. 331. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 575 be as small in quantity as possible in order to prevent the animals swimming away during the process, which is entirely carried on under the cover-glass. After the cover-glass has been put ona drop of a 1 per cent. solution of osmic acid is added and sucked through from the other side, then water, 70 per cent. and 90 per cent. alcohol, and finally water again. For the colouring of the now sufficiently hardened and fixed animals, Weigert’s picrocarmine process* is recommended. This should act an hour and a half to two hours, the preparation being placed in a moist chamber in order to prevent drying. After removal of the colour 70 per cent., 90 per cent., and absolute alcohol, oil of cloves, and finally Canada balsam are added. This process, which in reality takes only a short time, gives very excellent results for many Infusoria. In the case of others, however, the use of osmic acid is not so good, and with Amebe it is entirely without result. For these organisms, therefore, a 2 per cent. solution of chromic acid is preferable, which must act for two to three minutes in order to harden them sufficiently, otherwise in washing they readily swell up and burst. The remaining process is the same as the previous one. The duration of the action of the agents varies of course for different animals, depending upon their size and fineness—the most different Infusoria and Flagellata have been preserved in this way without manifesting the slightest shrinking. The cilia and vacuoles are quite life-like, and show the nucleus and nucleoli with an intense red colour. By far the best result, however, of the method is, the author considers, in its use for Amabe, the preserving of which had hitherto not succeeded. They are fixed in the position in which they are at the moment of the chromic acid being added. Even in the fine pseudopodia the vacuoles are easily to be recognized. The nuclei are also distinctly coloured. In a postscript the author adds that Dr. A. Gruber, of the Frei- burg Zoological Institute, who had previously found the process very useful for Rhizopoda and allied organisms, has since tried it on Heliozoa and found it to succeed excellently. Preserving Protozoa.t—Referring to the preceding paper, B. Landsberg considers that it is a disadvantage that all the operations have to be performed under the cover-glass. It is scarcely possible, therefore, to prepare clean slides, as foreign bodies once under the cover-glass cannot be removed. It is also to be doubted whether the osmic acid can act with the necessary suddenness and in sufficient concentration, and finally there is the danger of the object swimming away. He therefore proposes a method which obviates all these incon- veniences, and which even a beginner can soon learn. A small quantity of water being placed in a watch-glass or on a slide (without a cover-glass), is observed under the Microscope, and when an object is seen which it is desired to mount it is sucked up by a fine pointed capillary tube, taking care to have a little * Arch. f. path. Anat. u. Physiol. (Virchow) Ixxxiv. t Zool. Anzeig., v. (1882) pp. 336-7. 576 SUMMARY OF CURRENT RESEARCHES RELATING TO water in the tube at first, so that the animal may not be destroyed by too strong a rush of water. The water is then emptied out of the tube into a drop of 1 per cent. osmic acid on another slide, and the acid allowed to act for about ten minutesasa maximum. The animal is then stained with Beale’s carmine, washed with water, and after gradually hardening in alcohol transferred to oil of cloves. Another process is to be recommended for small quick-swimming Protozoa. After it has been ascertained that the water in the watch- glass contains many Protozoa a sufficient quantity of osmic acid is poured in, and the subsequent processes of staining, washing, and transferring to alcohol and oil of cloves are all performed in the watch-glass. The animals are so fixed in the sediment that it is rarely any are lost in sucking off the fluid. Then a drop of the oil of cloves is taken up under the Microscope in a wider tube, and the organisms brought away isolated by the capillary tube and put at once into Canada balsam. Although Canada balsam preparations have the advantage of greater durability, yet glycerine is to be preferred for many Protozoa. In particular, Actinospheriuwm Hichhornit is much more beautiful in glycerine than in Canada balsam. The frothy condition of the ecto- sare is shown most clearly, and the contractile vacuoles remain, as in the living state, prominent at the surface of the animal. Staining the Nucleus of Living Infusoria.—We are sorry that by the interpolation of the word “erroneously ” at p. 281 it was made to appear that M. A. Certes was not justified in claiming as a “ new fact” the staining of the nucleus of living Infusoria. The author of the interpolation, to whom we have referred on the subject, informs us that the fact of the note dealing with the living animals had momentarily escaped his attention. Double Staining with Carmine and Anilin Green.*—Mr. T. W. Taylor obtains very beautiful results from the following method of using preparations of carmine and anilin green { together. The section is immersed from five to ten minutes in the green, and then passed at once into the carmine, in which it remains from one to three minutes, the process being carefully watched in order that the carmine may not stain too deeply. It is then thoroughly washed in absolute alcohol, passed through oil of cloves, and then mounted in solution of balsam in benzole. The use of the benzole- balsam is important, as it has a decided action in fixing the stain, due to the presence of benzole. Two or three drops of each liquid suffice, and the whole operation is performed upon a glass slide, or in a, watch-glass. The woody parts of the section take a rich carmine, shading into orange, while the pith and light cellular tissue are stained a bright * Amer. Mon. Micr. Journ., iii. (1882) pp. 92-3. + Carmine stain: carmine 15 gr., ammonia 15 gr., distilled water 2 oz.; dis- solve carmine in ammonia over the flame of a spirit-lamp, add the distilled water and filter. Green stain: anilin green 5 gr., absolute alcohol 1 oz. dard ZOOLOGY AND BOTANY, MICROSCOPY, ETC. BTY orange-yellow. In a section (transverse) of the leaf-stem of the sago-palm, the outer cells, which are smaller and more compact than the more central ones, were dyed a rich orange-yellow, and their nuclei a bright carmine. The curious large ducts in the central portion of the stem, which, as a system, form in a transverse section a figure like the Greek capital omega, take a pleasing variety of shades, the cells around the edges being a bright orange, the central cells shading down to deep carmine. These sections of the midrib of the sago-palm are beautiful objects stained or unstained, and one of the best examples of curious cell arrangements to be found anywhere. The action of the dyes made from the above formula is quick and certain, and the effects very satisfactory. Cutting Sections of Coal.*—Some discussion has taken place as to the feasibility of the method mentioned in the ‘ Micrographic Dictionary, of macerating the coal in a solution of carbonate of potash, several authors finding that the coal still remained quite hard and impossible to cut. OC. L. Lord finds the following method to be easy and successful when tried on the particular kind of coal men- tioned by Huxley as containing macrospores and microspores in such abundance, viz. the Better-bed coal of Bradford and district. Grind achip of coal to a smooth surface on an ordinary school-slate. Then cement it to a glass slide, either with shellac or Canada balsam. If balsam is used, it must be evaporated until it is of such hardness that a dent can only just be made in it by pressure with the thumb-nail, then remelt it and fix the smooth surface of the coal to the slide. The coal may then be ground on the slate to such a thinness as to show the spores. The coal-matrix containing the spores cannot be ground sufficiently thin to be transparent, and if it could be so ground, it is doubtful whether there would be any organic structure perceivable. J. Walker selects from soft Iowa coal, some hard heads, so called (that is, hard lumps of coal in various stages of transition from good coal to charcoal), and well-preserved wood mixed with sulphide of iron. Breaking up these lumps and cutting out with a chisel the wood from the coal, which is the same as the coal without the bitumen, and breaking this in the proper direction, sections can be got both ways of the tissue, and when ground down thin make a good transparent object, or opaque with the condenser, when the sulphide of iron glistens like gold-dust among the woody tissue. W. H. Harris has tried repeatedly to get a good slide of ordinary — coal, and the outcome is one section only that shows any structure, and this was cut from ordinary marketable coal from [linois, U.S.A. A piece of the coal was cut about a quarter of an inch in thickness with a fret saw, placed in pure turpentine for some considerable time, and then in dilute Canada balsam, until it was saturated. The turpentine was allowed to evaporate, and by a gentle application of heat the balsam the section had absorbed was gradually hardened. One side was then ground flat, polished and cemented to the slide ; * Sci -Gossip, 1882, pp. 89, 136-7. Ser. 2.— Vot. II. 2 Q 578 SUMMARY OF CURRENT RESEARCHES RELATING TO when completed the other side was a simple repetition of careful erinding on a water-of-Ayr stone, just as an ordinary rock section would be treated, only with more care when the critical point was approached. Finally, Dr. C. H. Griffith, one of the editors of the ‘ Micrographic Dictionary,’ says he is “greatly amused at the discussion,” and suspects the writers “have been experimenting with the refractory anthracite coal too common in our coal-scuttles; but this being nearly all mineral matter, of course, does not yield to the action of the potash. Neither would it show much if so cut. They remind me of a former sapient microscope pupil of mine, who took to himself much credit for soaking a nail from the ‘ Victory, in the hope of making a section of it for the Microscope to show the structure. The coal for which this process is recommended, and which yields the best objects, is that which is more of a lignite character, and when so treated and digested with heat, is cut readily. Tomy own knowledge Professor Henfrey cut hundreds of sections in this manner.” Sections of Mica-schist.*—In a paper describing the methods he originally adopted for rock sections, Dr. H. C. Sorby says that it is possible to prepare thin secticns of mica-schist perpendicular to the foliation, although it is so friable that at first sight it appears im- possible. Having got a fairly thick portion and reduced it to about 1 inch, it must be wetted well with turpentine so that it may penetrate into the pores of the rock, and then covered over with Canada balsam and kept hot inside the fender. The balsam penetrates into the loose material, and thus supplies artificially what nature has failed to supply in not having hardened it sufficiently by infiltered quartz. It is well to repeat the process after a little time. By this means the weak points of the mica-schist and the planes of discontinuity are filled with hard Canada balsam so as to make it thoroughly hard throughout, and enable it to be rubbed down and the section left of the desired thickness. Paper Cells.;—Mr. W. H. Walmsley, in an article (the third of a series) on Dry Mounting, considers that the remedy for the appearance of moisture in cells is to be found in “ saerificing artistic cells of wax, with their pretty coloured rings of varnish, and being content with those of humbler and far more useful qualities. Paper, from which such dissimilar articles are now manufactured as love-letters and car- wheels, is our friend in need in this emergency,—not sized, or glazed, or calendered, but soft, porous paper of various thicknesses to suit our needs ; a thick blotting pad being exceedingly useful for cells containing objects sufficiently thick to require such a depth.” Wax Cells.t—Mr. T. Whitelegge proposes “a very simple method of making wax cells. A piece of glass tubing is first drawn out to a point so as to form a pipette, and this is filled with melted * North. Microscopist, ii. (1882) pp. 1384-5. Cf. also Mr. Rutley’s process, this Journal, iii. (1880) p. 849. t+ ‘The Microscope,’ ii. (1882) pp. 1-8. t North. Microscopist, ii. (1882) p. 194. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 579 white wax. The slip upon which the cell is to be made is placed on the turntable, and while it is spinning, touched with the point of the wax pipette, previously heated so that the wax may flow out readily. A wax ring is thus made quite as easily as one of varnish, and if the ordinary pharmaceutical white wax be employed, it will adhere very tenaciously to the slide. It is obvious that many varieties of rings may be made by modifying the temperature of the wax or even by warming the slide, and as an operation of this kind generally requires some little practice in order to obtain the best results, a few failures at the outset should not discourage the operator from further attempts.” Miller’s Caoutchouc Cement.—Mr. R. Miller, while not claiming to have discovered any new substance, has hit upon a new method of combination by which a material is obtained easy and quick to work and reliable in its results, and available both for making and sealing cells. It has stood a test of eighteen months. The following are his directions for using it :— To turn Cells. —Centre the glass slide on the turntable, and with a camel’s-hair brush previously charged with sufficient cement, mark off the foundation of the cell in width and size required, the turntable being somewhat rapidly revolved; dip more cement and apply directly before the first layer can set, and so on, always touching the top of the stream only, until the cell be raised to the height desired, then lay the slide aside in a level position to dry, Slight cells dry in a few hours, deep cells, say } of an inch, in two or three days. One hundred perfect cells may be turned in an hour by a beginner, and nearly twice that number by an adept. (Keep the brush clean and the bottle tightly corked.) To mount in Glycerine, Oil, Canada Balsam, or other Fluids,— Take a cell perfectly dry, apply or turn a sufficient layer of the cement round the top of the cell, slightly overfill the cell with glycerine, and put in the prepared object, place on the glass cover (previously tested to fit), press down the centre and edges of the cover until it is firmly in position, and with a damp brush gently remove the expelled glycerine ; test again by slight pressure that the cover is on the cement, and lay aside to set. A few hours afterwards the slide may be immersed in a basin of water and thoroughly cleansed with a camel’s-hair brush, wash again if necessary, and when thoroughly freed from all traces of glycerine and quite dry, turn a layer of the cement over the cell