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JKNNJNGs tbM. » full k,„„vto,l Jif ", , '' "'^'":'"«« ""'I «.« law, „.„ '1 !;"'"",,'""• """ " «'"1v an n...ler,U„ui„, „"n:;. , ^ - ^,^" -e of „„e Pm:™', ^^1, ';:;.■; .''I '"" ""i* to those of hi,ri,er aniii..,?« rl, "^ "^''^''" "lembers oC tho ».. ^ '"""sli .1 key t« Want, the other broadTuVp X 1^""'""''«1'-' -''^"ai w ^ J;:??" "' ""' '"'"^^ a'oiigone side of the bo.lv n m ""'" ^'''^ '»'»"t «"<1 i J, "' "'"■•"«' '"'<! which the ,uoutluuL"„ r "^ ""^'"«'«'»'I'-"gthe,c . H '' ''"'•'^^•^ ^'l>"<iudv «iUe (on Which tl c r:in '! """, ''^ •''■•^^'•''«»^f.'' J .^'^r""/- '^''- -'« on tl^e u„i„,al iscovored uSl « ! ?'""" '''^^ "'^ '''« '"'oral s ,' 't. '"'' *'"' ''"'>'-'-t« '» the direction of thrnlv I' 'T;""'"''^"'«'"<^I' it n,ove a. ,-,''" ""^"'^ ■^"'•'a-'e "f other the posterior e^^/"'"^"'^'' ''''"•^«'- «'''^ that nu/,:;!;,'^ , I" what u,ight I e oalJe,! H • ' ^""''■'■"'" ^"'^^ *''« •'"•-•kward, so that the a2 ! , ""™''' '^"'"'•"on of ail-u.s .,, . '^-'«. Now, When a cl' "« L"'? '"'"'^'•^'' ^^ the san e t ,e it "' "'' ''"••'» ^^^ike ''« »>y it striking again ^^' '. T"^"'"''^ '" ^'"' ^'"vironnK.nt /, n''"^''""^ "" '^« ^ong tion of ptrC„,!V''r'-'«« -"•" l'a«e.l on i„v r :^°* ^''^ '""'y ^ease their lOiJ 106 HULLKTIN OF THK UNITKD STATES FISH COMMISSION. movement, while those in the oral fjroove and the gullet continue active. Aa anon- 8e(|uence locomotion ceanes; the animal comes to rest against the solid body, while the cilia of the oral groove continue to drive a stream of water to the mouth. This reaction to a solid body may be callet; thigniotuxis. If the loose solid body is a mass of bacterial zooghea, the stream of water carries iniinbers of bacteria to the montli, where they pass into the internal iiroto])Iasni of the animal and are digested; thus Paramecium gets its food. But the animal conducts itself in exactly the same way toward other loose tlbrons bodies, such as bits of (;loth, paper, sponge, or the liiic, the presence or absence of material that will serve aa food having nothing to do with the production of the reaction. On the other hand, the substances held in solution in the water have a marked effect on the tendency of tiie Paramecia to react in the manner above described. If the water is faintly acid in reaction, the Paramecia are much more inclined to come to rest as just described. This is especially noticeable in water containing carbon dioxide. The presence in the water of an alkali in solution has, on the other hand, precisely the opposite ettect, tending to inhibit the thigmotactic reaction. 2. Any other change in the conditions, of such a nature aa to act as a stimulus, causes a definite change in the nmveinents, which is of a stereotyped character, being of the same nature for almost every stimulus. When stimidated, Paramecium swims backward, turns toward its own aboral side, then swims forward again. The same reac- tion is produced by stimuli of the most varied kinds — by acids, alkalis, and neutral salts, by heat, by cold, by mechanical shock. The reaction is the same wlietlier the stimulus first affects the anterior end, the posterior end, one side, or the entire surface of the atumal at once. The direction in which the animal swims has thus no relation to the localization of the stimulus. If the stimulus comes from the anterior tMi«l, swimming backward of course carries the animal away from it; if the same stimulus comes from the posterior end, swimming backward carries the animal toward it. If an injurious chemical substance diffuses in such a way as to first come in contiM;t with the posterior end of a resting Paramecium, the latter therefore swims backward directly int«> the substance and is killed. The turning is likewise without relation to the positi<m of the stimulus. The animal always turns toward its own aboral side, so that the absolute direction ill which it turns depends npoii the chance position of the aboral side when the turning begins. As the animal contiiinally revolves, both when swim- ming forward and when swimming backward, it is impossible to predict in which direction the aboral side will lie after the animal has swum backward a distance from its position when stimulation occiiis; and observation shows that when Paramecium strikes on one side against an obstruction, it is fully as likely to turn toward the obstrnction, after swimming backward, as to turn away. In the former ease it of course strikes the obstruction again; the whole reaction is then repeated. Owing to the continual rotation on the long axis, the aboral side will probably be in a new position next time, so that the animal will turn in a new direction, if this repetition is continued, the Paramecium is certain finally, by the laws of chance, to avoid the obstacle. The factors determining the direction of motion in ParaniiLjcium are thus internal; the direction of its movements has no relation to the position of external objects. This result is of fuiid.imental significance for interpretation of the movements of these creatures, and throws a flood of light on many of the phenomena of their life. Study of some other Infusoria in the light of the result on Paramecium has shown that the same ward, glass j poster morphi forwan of the certain He; e.vlendt into a ] snbstan leave it 8"bstan( niecliaiii attracteti edge of f Ibit J'an that man •t'iict, but produce t o'lfer tiuh *'t^»nmlns ( tl'o outer turns towi scheme of] more; leac boundary r many Par; appear to h In case shows that «s produced are prevei)t( It was i the one han the Paramec that they do I'> these the toward them, soon as the P "ll of these ti,„ Ufnonorelntion "'"8 on t|,„ „t,, tlie locttJizati,,,, 'interior end n«i liowever. tin, „h, NiiniuluH w.iH ,1... reflexes of (ho J] Tin: PROTOZOA OF LAKK KRIR. 107 saiiiti is true for tliese. Sinnmtimtutn (tmlthjuuni when stiiiiulatcd coiitnictH, Hwinis h;uk- ward, turns toward tlio aboral sido, iind swims forward. U'touclii'd with a spicuh' of glaas at its antorior ciul it swims backward, aicay from the glass; if touched at the posterior end it likewise swims backward, therefore toward the glass. Stciitor poh/- morphun when stimnlated contracts, swims backward, turns to the right, then swims forward, the direction of motion having, as in theother cases, no relation to hx^alization of the stimulus. Similar results, not yet jmblished in detail, have been obtained witii certain Flagellata, as well as with other Ciliata.* Hesidcs determining the general mechanism of the reactions of raramecium, an extended study was made of the elVects upon its activities of ditl'erent chemicals. If into a preparation of Paramecia mounted Jipoii the slide a drop of some chemical substance in solution is introduced, the Paramecia may either collect in the drop or leave it entirely empty. In the former case they show i)osi(ive chemotaxis to the substance; in the latter case, negative ehen\otaxis. As to what might bo called the mechanism of (rhemotaxis, the following was made out. The Paramecia are not attracted by the drop of substance into which they gather. They may };raze the very edge of the drop without swerving a particle from tlieir course so as to pass into it. 15ut I'aramecia when lirst brought upon the slide swim ra])i«ny in every direction, so that many will quickly come by chance against the edge of such a droj). They do not react, but swim straight ahead— the substance in tln^ drop not acting as a stimulus to produce the motor reaction abctve described. I»nt on i»assing across the drop, the outer fluid does, after the Paramecia have been in tlie drojiof the chemical, act as a stimulus to jtroduce the motor reaction. The Paramecium therefore, on coming to the outer edge of the drop, swims backward, thus returning into the drop. It then turns toward the aboral side and swims forward (in accordance with the general scheme of reaction above dcscribe'l). It thus comes to the outer edge of the drop oiwxt more; reacts again, and this being kept uj), is continually prevented from crossing the boundary of the drop into the surrounding water. The same process is repeated for many Paramecia, until in time tiie drop swarms with the Infusoria, so that they appear to have been attracted into if. In case of a substance in which tlie Paramecia do not collect at all, observation shows that the motor reaction fswimnung backward, turning, and swimming forward) is produced when the Paramecia come against the drop from the outside; hence they are prevented from entering and the drop remains empty. It was found possible to classify chemical compounds thus into two classes. On the one hand may be placed together those whiih do not produce the reaction when the Paramecia enter them, but throw the animals into such a physiological condition that they do react when they i)iiss out of a drop omtaining the substance in ([uestion. In these the Paramecia, therefore, gather and are said to be positively ehemotactic toward them. On the other hand are substances which produce the motor reaction as soon as the Paramecia come in contact with them, so that the aninnds do not enter • Th« reactions of i\ larcu luiinlHU' i>t' I'loto/oii liii\ e lu-uii stnilied since tlio above wns written. In all of tlieHB tliu (lircrtioM ot tiiniin;; \\i\a loiind to Ixt (leterniincd entirely liy internal fiietori', iind to ba\e no relation to the po.sition of tlio Nonrce <if stiniiihiH. The direction of motion ulon;; the body axis, on tli<^ otbor hand, was found in a nunibci' of imkch, for mechanical Htiinnli, to bo detcnnincd by the locali/ation of the HtiinnluH. I.oxodfn rontnim, for cxaniple, when tonched with a h1'''n8 ''od at the anterior end swiniH backward ; touched at the posterior end it swims forward. Kor chemical Ntimuli, however, the h/mcmci! of any Nuch de|ienilonce of the direction of movement on tliii localisation of the HiiuinluM wa^4 deuioiiRtrated. For details, see a ))aper by the author on "The n\ovenients and motor reflexes of lh& Flagellata and (Jiliula," in the American .lourual of I'bysiolo^y, January, I'JOO. 108 HlLLI'/riX nl' Tlir. IMIKl) SI'ATKS KISII COMMISSION. Hohitioiia of tliPHo (;onii)onii(ls at all, and may 1k^ said to bo iiefjatively diemota<;tic toward them. In the foriinu' j^roiip (siil)stun(;e8 toward which tho Piuainocia show poHitive chciii- otaxis) belong all acids, and salts whoso solutions have an acid reaction or contain hydrogen ions, as in salts of the heavy metals. In the group of substances toward which the Paramecia are negatively chemotactic belong all alkalies and substances having an alkaline reaction, as well as almost all compounds which contain ions of the alkali and earth alkali metals in their solutions. Certain substances take an int4.>rmediate place. Containing the ions of an alkali or earth alkali metal, they ^.o- <luce the motor reaction when the Paramecia enter a drop of tinid containing them; but having likewise hydrogen ions, they also cause the animals to react when they leave the drop. Kxani|)les of such substances are potassium and ammonium bichromate. In these cases the hydrogen ions seem to be active (in their characteristic way) in a more dilute solution, and, therefor", farther from the center of a diffusing drop than are the ions of the metals. Tiie I'aramecia, therefore, enter the outer margin of the droi» and are unable to lcav<^ it, while at the same time they are unable to pass to the center of the drop. They thus gather in a ring about the drop, leaving the center emi)ty. The cl.assification of substances into those toward whi(!h the Paramecia are positively chemotactic on the one hand ai' I those toward M'hich they are negatively chemotactic on the other, thus follows the lines of a chemical classiflcation; the former including acids, the latter alkalies and salts of the alkali and earth alkali metals. I'iXperimentsvtion showed that the relative injuriousness of solutions has compar- atively little to do with the nature of the chomotaxis. Paramecia are repelled strongly by many substances that are scarcely injurious at all, while they enter without hesitation other substances in which they are at once killed. The repellent powers of difl'erent chemical compounds are in no way proportional to their injurious effects. The rc»searches on chemotaxis have thus far been restricted almost entirely to Paramecium, but the general laws obtained for this animal promise to throw much light on related phenomena in others. As described above, positive and negative chemotaxis, or the collecting in or avoidance of certain chemicals, takes place through the mechanism of the general motor reaction first described. The only activity of the Paramecia concerned in it all is tlie swimming backward, turning toward the aboral side, then swimming forward, Wiien stimulated. The (|iialitative differences that seem a)>parent in their reactions toward different substances depend merely ni)()n what does and what does not act as a stimulus. The mechanism of c(»lle«;ting in or avoiding agencies or conditions, other than chemical, is exactly the sa:ne as that just described. In the case of tenijterature, for example, certain grades of heat or cold prodn<;o motor reaction, so tliat the Paramecia do nut enter these; or, if already within a zone of sucli temperature, they continue moving about violently till a chance movement carries them into a region where the temperature is not such as to cause a reaction; there they remain. In general, there- fore, the I'aramecia gather and remain in substances or conditions which do not cause the motor reaction, while they leave emi)ty sucdi substances or (conditions as do cause their one motor reaction. It follows that they collect in regi(tns of a certain tempera- ture, avoiding great heat or c<»hl, and that they collect in water holding in solution substances of an acid character, avoiding alkaline solutions. I'nder natural c(Hi- ditioi theiui in del togetl to qui thePti the P,i Tl in the course, in the amount cbangef backwa random reactit)!) stimulus niaypasf carbon c M» carboi Or, if it ( to be acti '■« by (;hai "loutb of Piiraniecii .joined by (c-vcreted This r ature, by ( tciHl to pn chance dir Thus 1 leaction to while undei It is ob out of cert! I)reserving ( show no iui '"^aine niaum their needs. conditions ai soon die. 'i similar anwu covering evei of the water s'i«:ht change though a few P'ants, the pr THK PItOTOZoA OK •'AKK Kiirj.;. 109 rf---=?F~^^^^^^ - amounts of certain ,.|.«m! "^''"''" *"• '"«"'■ ttMn.uM.h .'''■'' "''^'' •'''''''^'e.s cbun.es arc «/^h^ r S:^? J^ ''"' •"" ^'^" "^--01;:;.::^^ ^ '-« backward a short disfa,. 1 ! '^ ''' *' sf''"<Wus, the p. ^'""■'- ' ' these random one so far ^2' T '""'""'^ ""•^' -^'0 ( n a •,•;'*'''"?'. '''^''''"P'''' '^win.s reaction is reneafedl^r"' ''^•*"'*^ '"« c""cerne a ." "'''"''' ''^ "" ♦^"tirely stimulus. cS.l .1'""*'^ "•« ^•^^«'««-"mro es':',::;^'';"'''^ """''^•'- '^^"is -aypass b. chj:;t:';::;-;;;;;on« cause no i::,!;;:. "^^i r^j-^ ^--^^•^ "^' carbon dioxide, which th«v j ^ ^^'' ' ^ra.necia, where tli« JT ^ '^•■«"'«<-inni '"> carbon dioxide cle m ' ''''''^'''^- ^"^> ^ 'e nr o n T"' '' '^''"•^^'^ «''*'' Or, if it con.es „ co, tac m '?'"""' «« "'« i^t an ec u ? "'^ ''''''' ^""tni-in,. to be active tLT '"' '' '^"«'^' ««ft body it stol '"'"" ^''*'' ^^e others - by cha^: a b^ ;rr"^ --^ '^ «trean, onS^;;^ « -«' ciiiacontinnin, "'outh of the anhna sothrH '""*^^"'"' ""'^^ «trean. can- 1 Z I '"" '^" "'^' '^""d I'aramecium uZrlt? ^^'^^ '^''^'^ «-^ food. B, t , , "^ ^"'"^^'''^ '"t" the fined by oth^r;^ - r-^;^;-|e«nitei, ..i;:::t",r ^^^^^ '"'-''' '"« •eaction to Ite eoldi;.' ''"'T'' '' ^'^^'^'^cly s ,np e t v"! "''' '' " ■^^''°'""«- wbiieundero er on ;rT^:""'"^ backwTv ^t„ X''"^".'^''^ «'- '"ode of 't is Obvious t,::" e" , ;r ^:.^'"'^^ '-•«-'>' -'ea^es""""^^' '^"•""""•»«' i-vanl.-_ «bow no Lli^S'f i ;:"^'"'"''''-*«" -^1 cha ^" ;:.;;j^ r^ ^ -'c,uate ibr saM.e manner, if t ey r " -f f 'ir "' ''^'«" "^" cboi.l, ;,X ' ' '• "'^ ''"^'""-•'h " "'c»- needs. Cha ce ' , '''^^' "'^^'« "o po v^r^- '^ f,'\^'^^^^^^ the conditions and ffivin'i ft, r "'''"!/«ctor i„ brin^in/tVe P 'i. "'^: '^'^^'■'' "ct'ons to soon die. This .., ' ""*^ '^ the chances are ,J,r «'a«necnn« into nroner covering- everything J7,^,tL>' """'^'""■^ '"« cxac iy ' t'Tl "'" *'"^^*^ '•"'^' "f the water entir.t h,:^*, ^' ' 'J'-'^ncc.a can not n,iss i u d "" ;""^""^' ^""^''"'-'^ ^bffht change occnr si. triM^-^''^' '""""''« ^warn, and „' u ti ) ""'"'''" «"""'■^'■- tbough a ih^y hoars 1 «7'''t><"Ks, an.l soon scarce v ' ^ ^'^ thousar.ds. a ^"""■"■""»""'-«'-ti Ltsrf no BUl.LKTIN (IF THK rMTKI* S'lAI'i'.S KlHIt COMMISSION. those infusoria uppeiir iiiid diHaitpear in tin; tMiiture jar about hh the lower alf^iH do. The power of inoveinent, re);uhit«'d in the simple manner above described, is <;orrehited with tlie fa<;t tlnit, nniii^e phuitH, tliey live upon solid food (baeteria) and are therefore more liliely to get ttiis food if tiiey (;an move about here and tlierc. But tiie bacteria must be abundant in any ease, for the I'aramecia have no power of searching; for them, or of choosing them rather than any other substance. In future work it is hoped to determine how far the residts gained on Parame- cium are apjdicable to the Protozoa as a class, as well as to extend these researches to higher groups, building upon tlie foundation obtained by a study of these lowest organisms. In tiiis way it is hoped that the laws whicli govern the movements and migrations of animals, the causes of tiieir appearan<-e and tlisappearance at certain places or under given conditions, and in fact mncli of their relations to the conditions surrounding then) in the lake, may in time be made out. It is the belief of the writer that this is the most direct and certain way of unraveling the complicated network of relations which make up the life of the lake. In addition to the study of the reactions of the animals above suninuuized, some faunistic work was carried on. An examination was made of the waters on and about South Ilass Island, with the purpose of determining the abundance and general char- acter of the Protozoan fauna. The swampy waters of this region were found to swarm with Protozoa of all sorts, <dlering unlimited supitlies of material lor work on the group in experimental or other lines. Unfortunately, the literature was not at hand for complete identification of all the species observed, so that critical systenuitic work, of the soi't done on the Rotatoria, could not be cairied on for the Protozoa. Only those could be positively identified that agreed completely with species described in the standard works on the Protozoa — Leidy's lihizopoda, Kent's Manual of the In/iiKorid, Biitschli's Protozoen, Eyferth's lUe ciiifachstcn Lt'biHH/ormtn den Thier-und PftnnzenreiehvH^ Blochniann's lHv mikroskopinclie Thiencelt dett *'««« /<•««««•«, Pritchard's Infusoria, Khrenberg's Die I ii/imonNthierchen als rolhommein; Organ iiimen, etc. The following list therefore (lontaius the names of such species only as could be fully identified, and comprises thus but a fraction of the Protozoan fauna of the region. It is given in order to show something of the character of the abundant Protozoan fauna of these waters, as well as to jioint out forms that are of cspe(!ial interest as favorable objects for investigation. Especial attention was paid to forms which from their size, or fnmi the possibility of securing tlieni in great abundance, promise to be particularly favorable for experimental work. lioU folio a. ▲ 3. Ai 4. Pa 5 Co 6. DM 7. Dlfl 8. om 9- Dlffl, 10. Dim, I 11. Arce t 12- Centi 13. Bugij 1*. Acani Jill 15. Oikom nor 16. Anthoj iiaa 17. Oinobr 18. Bugleni wesi tlie t 19. Buglena 20. Buglena 21. Amblyo] 22. Colaciut 23. Colaolun Lake 24. Traohelo 25. Tracheloi THE PROTOZOA OK UAKK KH.K. Ill LIST OF SOME OF THE PRnTn7n. r 3- --t,:^;i^j, Ktrr -F"- ■"'- '■"- "■' "--'» - ■■■■ "■•• - ■• »»' or s„„„, ..,,..,,,,,, 2 ;,° "■""'"" "-•' II..",. -7 ";' ," "" "'""•" '"'"".I. ^^S=~?:£iS-"^':'- -,., II Co^ac^um steinu Kent. On S^T*"""' '''"'"' "»«« I«Ia".l. s .2SSfiS£^^^^^^ 112 lULI.KTIN OK TIIK INITKI) STATKS KISM (OMMIKHloN. 26. Traohelomoiiaa aapera Klir. Hwaiiip on .Soiilli IIuhn InIuimI. 27. Traohelomoiicia arinata Klir. [n ai|iiittio vi>;;otiiliiiii from I'.uhi i (arbor, l.nkn I'.riu, nnil from Kaat H\vaiii|i on South KaNN iNlaiul. 28. Phacua lohgicaudua Klir. From Kant lliirlioi'. I.akr Krif, ami from M\vaiii|iH on .Sontli IIuhm Inland. 29. Phacua trlqueter Klir. Kaxt llurlior, l.iikit Krio, ami JjiHt .Swami), Soiitli HaxN Nlauil. 30. Aataala triobopbora Kbr. On HliHlm trom KaHl llarbnr, Lakit Kriu. 31. Bntosipbon aulcatum iMi.j. In ,jar of <|i'ca,vinK Xiliuubu liilra from KhhI llarlior, Lako Krie. 32. Syiiura uvella Kbr. KiMt Sw»ni|i, .South ItiiMH IhIhikI. 33. Chilomoiiaa paranieoium Klir. Alnnnlant in tlHcayiiif; watrr-jilantM from any |>art of Lake Grin or tlif Nwaiii|>H on .South Hiihh lHlan<l. 'I'IiIh Ih ono of IId- Bpt'cicH that I'lin alwayn lio |iruciiru<l in iinlluiitcil (|iiantiti<>H at any tiiiio. 34. Moiioalgu ateliiii Knit. Ou Htciim of KpinUjUii plicatiliii from KaHt .'<\vuiii|i, .South llaNN Ulunil. 35. Peridluitim tabulatum Khr. In water-hottie collection from ii|i{iur H fi-t-t of f.aki^ Krie, I mile wi'Ht of South IhiHM iHlaiid; alito iu aqnatio plants from KaHt Harbor, I ako Krie, and from the Hwamp.H on .South ilaiM Inlaiid. CILIATA. 36. Traohelooeica olor O. K. M. In rtricitlarin from l'ortngi> River, Ohio. 37. Colepa birtus Khr. Swamp near liHli-hatchcry on .'^oiitli lla.sH litland. 38. Ampblleptiia meleagrla Khr. In ai|natic plants from Ka>tt Harbor, Lake Krii'. 39. Ampbileptus margaritifer Khr. In a<iuatii' vegotatiuii from I'lit-in May Ilarbtir and Kaal Harbor, l.ako Krii«. 40. Llouotua faaoiola Khr. In ai|uuti<' plantH from Kast Harbor, Kake Kriu. 41. Loxopbyllum meleagria Khr. On Myniiiihjilhiiii from Kast Harbor, Lake Krie. 42. Tracheliua ovum Khr. On I'triciilnria frutn I'ortagr Wivcr, Ohio. 43. Dileptua anaer <>. F. M. On ai|natic pluntH from Pnt-iu liay Harbor. Lake Krie, and the swatupa nrar the iUh-hutchery on ijoiith Ha.ts iHlaud. 44. Naaaula oruata Khr. Kast Harbor, Lake Krie; Furtaf^e Uiv()r,Ohio; Kast iSwamp, South linsH iHlaml. 45. Olauooma aciutillaua £hr. Common in uulttireH of decay iU}; lake plants. 46. Colpidlum oucuUua Kcbraiik. Abundant in iufuHiuim of docayin}; (JemiophyUum from the bottom of I'lit-iu Hay Harbor, Lake Krie. 47. Parairecium caudatum Khr. Abiindimt in cultures of deoayinj^ lake plantH from the bottom of I'ut-iu Kay Hurbor, Lake Krie. See pp. 1U5-11() for au accouut of the laws of the movemeutH of tbia animal. 48. Urocentrum turbo O. F. M. Abundant in decuyiiiK ('eiaU)pUyllum from tlie hot tain of Put-iii Buy Harbor, Lake Krie; also in water from Kast Swamp on South Kass iHlaiid. 49. CyoUdium glaucoma Khr. Iiijar of (leeayiug Ae^ini/(o luiea from Kast Harbor, Lake Krie; many. 50. Spirostomum ambiguum Kbr. ICoat Harbor, Lake Krie, and LIk- i^vvumpH on .'^outh MaHS litland. 51. Buraaria truncatella Miiller. This cuorniouH infiisorian wa.s common in the Hwanip near the tish- hatchery on South Ita-ss l.sland. 52. Stentor ceeruleus Khr. In aiiuntie vogvtatiou from Kast Harbor, Luke Krie, from I'ortuge Uiver, Ohio, and the swamps on South Hasa Island. 53. Steutor igneus Khr. In KUnha from Kast Harbor, Lake Krie. 54. Strombidium turbo C. and L. In docayiuK SiliUa from Kast Harbor, Lake Krie. 55. Halteria graudinella Miiller. Many in L'triniltiria from I'ortagu Kiver, Ohio. 56. Tintiniiopsia cyliiidrica Daduy. An empty shidi of what appears to be this Bpecies, recently descrilied by Daday, was taken in the water-bottle collecticm from the upper 3 feet of Lake Krie, 1 mile west of .South Itass Island. 57. Codonella cratera Leidy. In towings from I'ut-in Itay Harbor, Lake Krie. This seems to be the same as the Knroiieaii CodotivUa laciiHtrig, but L'-My's name has the priority. 58. Holoaticba myatacea .stein. In the water'nottlu (<.i:i> (ion from the upper 3 feet of Lake Krie, 1 mile west of South Bass Island. 59. UroleptUB muaculus .Miiller. Few in decaying Mtei' , ;i >m Kast Harbor, Lake Krie. 60. Oxytricha fallax Steiu. Common iu decaying; >'trali i'.iUum from the bottom of Put-in Bay Harbor, Lake Krie. ' \ \ '"■■>. \i \ TIIK PIWjTOZoA of lake KUIK. 118 61. Trlohodina pedloulua Klir. On IHatilomuii fioin t<iwiii);H in i'lit-iii Hiiy llnrlior; mi llgHrtt (Vnm Kuat liftrbor, I..uk<i Krlt 62. VortlcelU oouvullaria I.. Voryalninilunton uIkh' rroni I'.iutt .Swrniip, .'^nnlli Hiihh iNlaiiil. 63. Vortloella ohloroatigma Klir. rnrininK liirKu ^riMMi lutttlioit viHiUlii to (lif naktul )•><•, on tlii< y«KOt>^llon from Kimt ''.tvnin|i, Hontli Mamn UIiiuiI. 64. Vortloella rbnbdoatyloidea Ki<llirott. (.'ointnon on .Itttihunit in tiiwlnf;ii rrtnn l.itl<ii Krio. 69. Zoothainnium arbuaaula Kbr. In aurfiti^otowiiiKH in I'litin llity Marbur, Litko Kritt, utlurtiiil tn lloulinK inuttur. 66. Eplatylia plioatllia Khr. Abmidiiut uii Chaia froui Koat Bwump, Kontii I(i.>«m InIuikI, in ('<ini|iiiny with Megalotroeha aUiofltiricaui. 67. Va^ioola oryatalllna Khr. On iii|iiiiti(! phintH Troni Kiutt Swiunp, .Sniili Miihh !Nian<l. Wlmt ae«<iiu tho hiimio form iH oiton found iiii t'ragiUaria in tuwiuga truui Lake ICric; tl'eNU8|ii!ciuK'n« are ulwaya uiiu^h muuiler, however. . t* SUCTORIA. 68. Aoineta myataolna Khr. On floating llovroHe material taken with the t<iw not in !'ut-in Kay Harbor, Luke Krio. Wbilo the fauiiii iiibabitiii{( the plaiitH of tlio bottom and ulioiit thu ttlioroM of this part of Lake ICrie is vory rich in Protozoa, both in the number of HpocicH and of individuals, the open waters of tho lake contain very few. Thouj^h 'I'i <pei'i*'H are included in the list, us taken from the waters of the lake itway from shore, most of tlicsu were present in very small numbers, and none were iibundant. The si>ecies of the fore<;oing list found iu the open waters of the lake, and on that account apparently to bo considered limnetic, are the following: A mirba prolfitn. J can tkoc.iigtit vhatoplioira. Aimrbti rilloia, IHkomonaii termo. Amiiba rariioon. Eiitjlena riHdis. Coliirinm uleiuii. Colariiim veniciilognm. J't-ridiiiiitm tahu latum. Tintinnopgin oylindrica, Vodonella tral<:ra. I'amphaguH hyaliiiuB. Cocklioiwdium bilimbosum. IHfflui/la curoiia. lHfflu(ii(i ijtobitlosa. Jrcella rulijaria. IfoloHlicha iii!)ilacea. 'JVivhodiiia pidioaliiii. I'ortk'elta rhahdoHlyluidtg. Xoolliamitiiim arhiisciila. faginicola crijutaUlna (f). Acinela myttaviua. This list includes a number of species not usually recorded from open-lake waters; these are chieHy due to Professor Keighard's collections with the water bottle, which were made as follows: A large corked bottle was sunk in the lake to the desired depth, the cork pulled from the mouth, and the water allowed to till ihe bottle. The water thus secured was then filtered, so as to i)revent the escape of even the most minute organisms. Collections were thus made from the open lake 1 mile from any land, where the water was fathoms deep. Water was taken fro.>. the surface layer not more than 3 feet below the surface. Collections so made contained regularly a number of minute Protozoa not usually accounted limnetic, namely: Aiiiitba iiroteui. Amuha eillusa, .Imirba radiosa. Cochliopodium bilimbosum. Viffliujia globuloaa. Eugleiia viridia (unoe). I'eridinium labiilatuiii. Tintinnopsis vyiindrku (only onco). lloloativka myatavea. The list is remarkable especially for the three species of Amcrha and one of Cochliopodium. These rhizopods are very minute, and would be lost jy the usual methods of collecting. Contiuuad thorough plankton work of the sort carried on by Professor lleighard maf show that these are proper members of the limnetic fauna, Difflugia (ilobuloita was one of the very commonest limnetic forn)s in all sorts of coUectious from the open lake. V. C. B. 1890-8 I! BUM 114 BULLETIN OP THE UNITED STATES PI8M COMMISSION. The passive limnetic forms incladed in the preceding list are: Oikomonas tcrmo, on floating lloccose luatoriul. Colaciiim steinii, on IHdptomus, Colacium reiiieuloiium, on Cyclops. f'ortiveHa rhabdostyloides, on Jnabirna, /oolhamnium arbiiscula, on l)oatin<; ninterinl. Vaginivola cryatatlina (f) on I'VaniUaria. Aoineta mystavina, on flouting floccosu material. The following species may be noted as of special intiTcst because of their titness as objects of investigation in experimental or other lines: ^ Vhilomonas parameciitm is a flagellate form tliat can always be procured in unlim- ited numbers by simply allowing the aquatic plants to decay in Jars. The necessity for large numbers in carrying on experimental worii needs no emphasis. The ease witli which a Protozoan can be cultivated in the laboratory is almost the most important element in its availability for investigation. The species of Euglena, Vhaeun, and Trachelomonaa are always to be had in large numbers from East Swamp, South Bass Island. Tracheliiis ovum, Dileptus anser, and Nasaula or«rt/rt are ciliates which are valuable for certain sorts of work on account of their large size. Tlie same is true to a more pronounced dsgree of Spirostomum avibigiium, and especially of liursnria truneatella. The latter is an enormous creature for a unicellular animal, being a millimeter or more in diameter. It could thus be handled in the same individual way as many of the large Metazoa. This animal was always procurable in small numbers from the swamp near the fish-hatchery on South Bass Island. Doubtless a little experimentation would discover a means of cultivating them in large numbers. Perhaps there is no other Protozoan that would be so favorable an object for an investigation into the effects of localized stimuli and into the question of the localization of functions in the Protozoan body or related problems. Other ciliates that could always be procui^ed in large numbers are Glaucoma scintillann, Coljndium cucullm, Varamecium caudaUim, Urocentrum turbo, Cyclidium glaucovia, and Vorticella convalUiria. For Khizopoda, three species of Difflngia — D. globtdom, /). lobosfoma, and D. corona — are particularly abundant and might be used for work on this group. Cul- tures properly managed usually resulted in obtaining large numbers of various species of Amoeba. Species of Volvo.v, Eudorina, Fandorina, etc., swarm in Knat Swamp, South Bass Island; they are not included in the foregoing list. A study of the ph^-siology of these creatures, transitional as they are between Protozoa and Metazoa, promises much of interest. Dartmouth Oolleue, Hanover, N. IL, May 25, 18!)'J. 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