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DIiBRA HY. OF THE MUSEUM OF COMPARATIVE ZOOLOGY ASKS GIFT OF ange nA CN, ae oul A a: alte oT IM Ge ; ba a Te Cla cn ihet ed “i DL ies Te ak i m4 . ; ia - eo Og A LABORATORY MANUAL INVERTEBRATE ZOOLOGY BY GILMAN A. DREW, PH.D. PROFESSOR OF BIOLOGY AT THE UNIVERSITY OF MAINE; IN CHARGE OF ZOOLOGICAL INSTRUCTION AT THE MARINE BIOLOGICAL LABORATORY, WOODS HOLL, MASSACHUSETTS WITH THE AID OF MEMBERS OF THE ZOOLOGICAL STAFF OF INSTRUCTORS OF THE MARINE BIOLOGICAL LABORATORY, WOODS HOLL, MASS. PHILADELPHIA AND LONDON W.B. SAUNDERS COMPANY 1907 a ” ae 4 a C.F 7 i y eye Rey “) Px “2 ie. an Toner PISS ee loan . Ne Ar ae Area, “ ‘a - 7 ee i ¢ ets « ‘ | CHA AL | a: AENIDOS COG Cab CAM SE0IKEN A: Copyright, 1907, by W. B. Saunders Company : F = : ‘ . PRESS OF 54 W. G. SAUNDERS COMPANY ie -,4 PHILADELPHIA & — = ~ . ef he + ae & é a oem = e ¥ a PREPAGE, THE present manual has for its basis a set of laboratory direc- tions prepared by members of the staff of instructors to meet the needs of the class in general zoology at the Marine Biolog- ical Laboratory of Woods Holl, Massachusetts. Those who were associated with me in the preparation of the first notes were Dr. Robert W. Hall, Dr. James H. McGregor, Mr. Robert A. Budington and Dr. Caswell Grave. Other members of the staff who have either aided me in modifying the original notes or who have added others are Dr. Winterton C. Curtis, Dr. D. H. Tennant, Dr. Otto C. Glaser, Dr. Grant Smith, Dr. John H. McClellan and Dr. Lorande L. Woodruff. Each year for the past six years the directions have been changed where experi- ences indicated changes should be made. Probably few instructors will find it desirable for their stu- dents to follow closely all that is given in this manual, but it has seemed better to arrange the matter in a logical order, and in some of the forms to call attention to only the important points of anatomy or adaptation, than to try to make the directions for each form complete in themselves. To make the directions for each form complete would necessarily add much labor for the student and would, by the repetition of well-known facts, tend to blunt some of the new and important points to be gained. The type method of laboratory study has for many years been the prevailing method, but care needs to be exercised to keep students from making everything conform to type, and in lead- ing them to see the wonderful adaptations that fit the different animals for their particular lives. The manual is not’ intended to lead students to a knowledge of comparative anatomy alone, but to an appreciation of adaptation as well. It has fallen on me year by year to see that desirable changes were made in the directions, and it has finally been my lot to put them into their present form, but much of the credit be- longs to the men who have been associated with me in the instruction work at the Marine Biological Laboratory. Tur AUTHOR. May, 1907. iii CONTENTS. PAGE mR NS NS gio ass Bo ses. SS gece a hetend oa cee a enn WN 1 oT DO he Be aS hae hee a en a OY» LLY Wiehe SNE) 3 PUREE IOAMEINOUCULS 23 277 both unin e2.) 0 25.5 ee ae ae 3 SUCRE APIATTNRRE TH) ot Cony tn ee et eo kb ti Re ne Re ie 4 mevnospherium.or Actinopnrys .... 0: sence se ehone soe e- 5 SRR MIE eS PHTOEUAY 0 Ape Ete ecvtn tata rise hurt ant Mae Nm, ene ey oe 6 PREPS Gh ol Ned SA ewe Si rn ee ic tyes eh ee Oe SN et 6 MUA PsP ee Ra a cco BC. SA ae bli ee Oe OS d “CT ETE TRIICLT EES Se gp Sit eS Re tel RRA SEE EAS BO lt C3 Tig Png 8 be ETT EVE te I iS ie a RCE ee eke tL aoe 2d 8 ERE PERMONT RE ORES erie scm a ee PR he fay eeu Me 8) ere IMI Me EN eyo ts eh, ets rs Batia e ks Va a aes aaa RESET NG ee tT re ary CPS SS cybhe Gy mee RS ty SN PLL. 10 SPOS ELITE) SPiN ee ae Pt EOD hd Ba caer AML Dt 10 Seema APRBEEA Seat SE Fcc, wee tee eee glee oe oe 11 na Pale teste cae Sete cee ie © eye a Pg uke Me rahe a) ) ny eR ae fat OE TELE G8 15 a a a ce ea eee aang a PPR || 13 ED Cer Mitre Sais na sts ole ey oo ee 14 RerremA MEE tay et ar. eng il See ngae th eg ees Is ae Roe 15 MTR 8 x he ny lanl Be ean uy Phir. ay Rees oe ee 18 RR TMCIE NORA PhP Re ae Ie Nk em og nl vk Md wa 6k lee OO 20 Pence resn- water Pole py. oi. su cee yan ete 20 VESTER LS ee SEI ae OSG ea ge NT er Wal CR a 8) 2 22 ETE ELE DS ts Eek Re a BR oe cen RTT SOR TS Pa 24 Seana TTESERAL eer pcs oot Ee ia bt ks od aaa 25 STOTT 0 2 || ee ag Pee een es) TS MT ea aL 27 TITEL ESEECY CLES iy ISS geese ae ee ire Soka eeaMaie o=2e0 ONE a 27 UMEDA te acti aca ic ey Root nek, Nghe i 7S in awd Ca aT PAN ee Llyn Bib oho aeee ns cea ita 5" eee eae 27 os SEES oR SR lg oa ne i eer el PS ae EN ee 30 PACT tha | SCR AMPIIONE) oo: 3.-s oS. 5 coh 5 i, eas 30 AME MTUVEL A Shc eet ra Ne cee ee Se ON pies) e 32 MIPS TAMMIsn etA Bae Se MES OAM OUND SoS oe OY 32 eM UTE NC EDEN 6 Sc. coi occ oes Res oe a he Sie oT Pek 35 SURE TEMRCI NETO E IES ily oy 22 ory ee ec hee ee iar Ls 36 rem E RU PRICLOCTULALAS ooh So hd LS ks RE eg ek NG Ln 36 InGcionra or Sy nccelidiim Fs. ek 2k athe ae Ss caea es s EY Lo STE SLC WPT SONS of SIRE al crcl ee Se seit aad Ruane get inhale CNC Se 39 Enema olcecids (Piston) .ec.65 ss icles ox p aeenishee’s cists oe 2c 39 SPORES eet ot, iach ats re eS ee ee bey ee 41 Proccemoniriiii: ACMIAbUOE b, > <.o55 36-6 anv ea wre cleek aw erce hak 41 vi CONTENTS. PLATYHELMINTHES (Continued). PAGE. Wee TIA ta 2 oo hee bie hed ss Se ae 44 Petenstenwaa . os. fo a ce Seo we oe - sade 2 2 ee 44 NE MATHELMIN THES.) occ. 025 toes tea i 46 ane ARRE ores ae iv Soke Ss Lee Bea OE eas Be eS Oe 46 rel sa Se, Oe lee Sn y's Wa ees 47 TROCHMULMUN PRES... so fois bees os tot eb. he 5 os. he 48 Happen 2 oo eee ek See OI aa 48 Brachionus (A. Rotiier):.. 2 svelv22t. 222 =. >... Se 48 BTA AULD A. ee ee ee wate IRS 1 Sk 5 eo bole os, 50 POU cls) oh 4. odo Pe Ree ne eas Sod orn 50 Bra, 32 6. Gea eas tee ew awe oe a 50 Phimatella 3 Soh 8 ho es oo 52 RENEIOPODE:. 6. 544006 (0s a! sa ee a eee En 52 Tereiratialina. «2.00 ace 45 < oe so os oe eae nee ee 52 BOHINOMERMATA « boc: sus oo. Re ES OR ee 54 ASTERGIDEA™ oo s:c 0. oS oaks Soe hoe een 4 os ee 55 Asterias (Starlish) 220. ix. <2. ae neda- 2: oe 55 OPHTIBOIDEM. (40522. oe 2 dS ee oe eo 60 Ophiura (Serpent-Star) .-..-... 0... +. +++ +. +> + ee 60 FUCTINGIDEA ©. 0a5 20 oo = Kr debs oe one Gece ee er 61 Arbacia (Sea-Urehin) ...... 5... 5.2.0. os: - ne 61 FIGLOTEURGIDEA......0. 25526 02 ns bea Da on ee 67 Thyone (Sea-Cucumber)::....-.4.- ¢-.55. i. 6: 40 2 67 PU TOTON VIDA: ee he foe oe dw baleen oe ee ae ne ae ee 70 CraeTorObA.. =). 600 lois soho amas oe Le 2 71 Nereis virens (Clam-Worm)>...¢. 2... <... 1: 5. 4.342, 71 Lumbricus (Karthworm) .....:... 22... 202.2 ee 74 Autolytus cornutus 2...) 2... o. <2. 922+ ee ee 80 Lepidonotus squamatus ... 2... .. 2. 2.2.26) 33s 81 Diopatra cupreas... 25/2. .<%. 22 Jae 2% El eee 81 Chetopterus .. 25s 62 2 oe a OS le 82 Amphitrite ornata:. 0...) 0s02-25 V2 oie ee 83 Cistenides gouldit <2... 2. 22. de ee 84 Clymenella-torquata s- 2.2). as ae ee aes 84 Arenicola cristata... 2.2.5 62 4. ease sa 3s eee 85 Sabella microthalima ........... 5. 72 «+ sale ee 85 Hydroidés. . 222 ews on s'. See 3 Se ae ee 86 Spirorbis borealis ...... . 2.2.0... 3/25. Se 86 GEPHVREA . 2)... J. ee oc Pe eee See 86 Phascolosoma... 2.36. vcs 5 seis 62k 2 Oe ae ee 86 MOLITUSCA |... ce bd as 22 ee Oe 89 LAMELLIBRANCHIATA .. 2.60 oo ob nee Ae ee 91 Venus mercenaria (Quohog) ...... -... -.¢)55.+--- >> +- = ee 91 ¥ oldia limatula... 3...) 542T 2. Uae 99 Mytilus or Modiola (Mussels)..2>. oc. ..0) 2: 37 >. 100 Pecten itradians (Scallop) ....2... 2. 22S 3.-8- 2s See 101 Ostrea virginiana (Oyster). 20.6... 4 eae 103 Dolenomysa «oo... ws se Se a ee ok 2 ee 1038 Mya arenaria (Long Clam) ... 2: i..03.< 27 2 se 104 Ensis direetus (Razor-shell Clam) .:......... 22s. sag)... spe CONTENTS. Vil Mouuusca (Continued). Pace. oe DRE ie, Sane eats ek SN arte ee a RO 106 SU MRMEONIRCET eM Geete ox cy Ce EY har tg Ae xs rile 106 SLE EA tite Soa Sih Gh OR alr SR hei So RS es en 107 Pema ye Liane es oY LS. x See ge Aceh ab e's wht cine bn 107 MNP MarR GLENEEN) 52 Goo sock nee Merscere Ha ccie «se oe mle Dae 115 EN Fact ones 5 Ph ole Fk as oA De tlw sie adn 4 ae Ao 124 A SRMRINEE Sa Cpe ee Sn ES lath ores Gigs wea tee a ive SAA, Oe ee ee 128 onmiares amenecanns.(LObSter).. <--> «0... «ea dkms paeeedee ialmecves nastatus¢(iiie Crab) i... .0.02<. 000 oo ee ee ee ee Papacuras (liermn Gra)... 226 es ooo cece see OO ee ee 138 MRE PENG Sane occ 52 2's 15. oko s nice eaten te de Spe 139 ETE | Te Ry Ba ERATE a i pA RO Perr at en er gre LRT OTE AE 139 LS SCE RO ier tO Rat On ee Mee OR ead eT Lorine ent sor 141 alorenestia (eachah lea rst ace) Gala soo sa eee 141 Porceiho or Oniseus, (Sow-Bug) . 5... 00.7. e252 2c eee BAS (WET DEE] [Pan eat ii aie ae an eee ool mananre i Same onece eS Waa ate ge 143 Drancaipus (lary Sirimip)s:. os.) 4). okies. sien oe EC HIAS nega Son piso Naa te Oey SU Re ee eee ee 144 LOGUP TSS eee 2 or ea a oar ge ce Pema ae 145 Peereerae PENI MOISE a. oe og 5 oe 2 ak nite ae oe ee oa 146 Mepasat eee Pear NACle) 2502-25 cists sc heen ewe seake ees 146 PMR ETUAERSR vente, fry Oh nate re: eee gs HU See eae Pe et 147 Marmsiine (larmesiioe Cra). 2. .en Fs as oie se ees He eds ane 147 Pee ARERN SIRE FIRED oh 2 ccs teres eon sa Craie ey eee, DR 149 ipeira Cr OUHE- WER Opler) 22. toes ca Ss ome Pee SE ea eee 150 EDU TUES ER SO gene Pa eg eo a ae 152 MYRIAPODA.. Sty EON rca ee Meme Say ts 2 Lithobius (Centipede, Earwig). . IE SE Sn OE Re eH ge Ne 152 RE ET OUSARE IES i aes oo )-s ae ue wane eee cee ae oo eee 153 OR en ica as ge Bit hai ote en eae nat coe wo Sg eke 154 Peerig Hii (tTASBiGpPPe’) s.408 "San ain sca ee ae cs oe os 154 Peas melitieds (HoneyBee). oo: oa. ss" age nc oe ai ee 159 Pe ORE ee oe Shs Perce ee ig, Ue oats wn ged Baha PE eel ae DS 164 Demet Mey a ets ec saa x Sk ey yee RR ens od a ee 165 ives mame UEMOIS fc 6 nt ck Sa bh oe SSS Oe 165 REPRE Ss otic act re as crag ime ee Sagat: 2 Soy one cee 168 Rab nat cho Sgr ch Pe caer 1 Pee eon inl < SR EE 169 PEMIATOSCUIM (CAE OPK). 2.5 x sot Stas es gees 2s Oa tee ee 170 STUNDE, COOPAN LONI rok ta 5 2 acc 1 2 -0is Stags cc She oy Mies + Peotone somes 172 RURER MRT AR A 2 8 enn Wate et Be 8 abe NS Cone aa di No Ie ARE 173 te Wie) ol Si tasg) tol 28 ite ea ffs Bier gies eg mo REC ene ac ee oe SLB 173 a FOR GUIDANCE IN MAKING PERMANENT PREPARA- $e REIS Se ar ig OA NR ne Ae Seer ST oe er ROR ar eo Sag aad ER 175 DEEN gto. co On ahs ok Soe aed ee ea eee eee ar a id aio rw oad 181 MNOS Se Se Sane whinge akg he a eR wae es s hehtate Sond = 195 INVERTEBRATE ZOOLOGY. PROTOZOA. Unicellular Animals. Cuass 1. Sarcodina. With changeable pseudopodia, during adult life. Reproduction by simple division and by spore- formation. Subclass 1. Rhizopoda. With lobose or reticulate pseudopodia. Order 1. Amoebida. With lobose pseudopodia. (Amoeba, Arcella, Difflugia. ) Order 2. Reticulariida. With fine branching and anastomosing pseudopo- dia. Shells, when present, usually calcareous. (Microgromia, the Foraminifera.) Subclass 2. Heliozoa. Typically spherical in form. The pseudopodia, which radiate from the entire surface of the body, are ray-like, seldom changeable, and usually pos- sess an axial filament. (Actinophrys, Actino- spherium, Clathrulina.) hile 3. Radiolaria. With ray-like pseudopodia, and with a chitinous capsule inclosing the nuclei. The skeleton, when present, is formed of silica or acanthin. All are marine. (Thallassicolla.) Cuass 2. Mastigophora. Motile organs in the form of flagella. Repro- duction by longitudinal division. Colony forma- tion is frequent. Subclass 1. Flagellidia. With a definite anterior end on which there are 1 1 2 PROTOZOA. one or more flagella. The members of one order (Choanoflagellidia) have one or more collar-like processes about the base of the single flagellum. (Mastigamceba, Proterospongia, Euglena, Pera- nema. ) Subclass 2. Dinoflagellidia. Usually with two flagella, one encircling and the other directed away from the body. (Peri- dinium, Ceratium.) Subclass 3. Cystoflagellidia. With two flagella, one of which is modified into a “tentacle,” while the other is short and con- tained within the gullet. (Noctiluca.) Ciass 3. Sporozoa. Without flagella or cilia in the adult period of the life-cycle. Reproduction is by spore-forma- tion. All are endoparasites. Subclass 1. Telosporidia. Reproductive phase of the life-cycle is distinct from, and follows the trophic phase. Order 1. Gregarinida. The young stages are intracellular parasites, while the adults are free and motile in the digestive tract or body-cavity of the host. Sporulation occurs within a cyst during the free period of the life-cycle. (Gregarina.) Order 2. Coccidiida. Without a free and motile adult stage. Sporula- tion occurs within a cyst, during the intracellular period of the life-cycle. (Coccidium.) Order 3. Hzemosporidiida. Living chiefly in the blood-corpuscles of verte- brates. In many forms the entire sexual period of the life-cycle takes place in an in- termediate host, as the mosquito. (Laverania malariz.) Subclass 2. Neosporidia. Reproduction takes place during the trophic phase of the life-cycle. Order 1. Myxosporidiida. The initial free stage occurs in the tissues or the cavities of the organs of the host. The adult form is amceboid. (Myxidium.) AMCBA PROTEUS. 3 Order 2. Sarcosporidiida. The initial stage of the life-cycle occurs in the muscle-cells of vertebrates. (Sarcocystis.) Cuass 4. Infusoria. With motile organs in the form of cilia during all or part of the life-cycle. Nucleus dimorphic (macronucleus and micronucleus). Reproduction is by simple transverse division or by budding. Subclass. 1 Ciliata. With cilia throughout the life-cycle. Order 1. Holotrichida. The cilia are of approximately equal length and thickness and equally distributed over the body. Trichocysts are present. (Prorodon, Parame- cium.) Order 2. Heterotrichida. With a uniform covering of cilia, together with an “‘adoral zone” formed of cilia fused into mem- branelles. (Spirostomum, Stentor, Halteria.) Order 3. Hypotrichida. The cilia are limited to the ventral surface of a dorso-ventrally flattened body. Cilia often fused into cirri, membranelles, ete. (Oxytricha, Pleuro- tricha, Kuplotes, Peritromus.) Order 4. Peritrichida. More of less bell-shaped in form. Cilia usually reduced to those constituting the adoral zone. (Vorticella, Zoothamnium, Lichnophora.) Subclass 2. Suctoria. Usually possessing cilia only during the embry- onic stages of the life-cycle. Tentacles adapted for piercing and sucking are present. (Podo- phrya, Ephelota, Acineta.) SARCODINA. AMOEBA PROTEUS. Amcoebe are usually easily discernible under the low power of the microscope as irregular, semi-transparent, granular bodies. Find a specimen in the material provided, which is known to con- tain amcebe, and determine the following points: 1. With the high power observe the peculiar method of loco- 4 PROTOZOA. motion, the constant but slow change in the shape of the body by means of projections, pseudopodia, or “false feet.” Make sketches at intervals of one or two minutes to show the changes in the form of the body. 2. Observe the peripheral zone of hyaline protoplasm, the . ectoplasm, and compare this with the inner protoplasm, the endo- plasm. Observe in detail the formation of a pseudopodium. Does the endoplasm extend into the pseudopodium? Can you explain how the movement is caused? 3. Find a clear space which appears and disappears at inter- vals; this is the contractile vacuole. Determine the length of time between successive contractions. Are the intervals regu- lar? When the vacuole contracts what becomes of the contents? Do you know its supposed function? 4. Note the oval or rounded nucleus moving with ha flowing endoplasm. What is its structure? 5. Food materials in process of digestion are readily seen. Of what do they consist? They are contained in gastric vacu- oles. By careful watching, it is often possible to observe the man- ner in which food is ingested and the manner in which the undi- gested matter is egested. Make a careful drawing of an Ameba. Ameoebe of various kinds represent in many respects the simplest type of protozoan, and are therefore placed in the first class of these animals, the Sarcodina. The individuals of this class all possess pseudopodia, but many are quite unlike those of Amoeba. Look over the figures of various Rhizopoda. If time and material permit, study Ameba verrucosa, Arcella, and Difflugia, and compare them with Amceba proteus. Do you understand how the shells of the last two genera are made, and of what service they are? Why are not shells good for all forms? Drawings of these forms are desirable. FORAMINIFERA. With very few exceptions Foraminifera are marine and pro- vided with shells. Empty shells from deep-sea dredgings or from ACTINOSPH/RIUM OR ACTINOPHRYS. 5 the sand beaches of such islands as the Bermudas may be had for study. Examine them with a low power by reflected light. 1. Carefully examine various shells, compare them with each other and with figures. Notice the great variety in size and shape and determine how the chambers must have been added during growth. 2. Observe a single opening in a shell, and determine whether the general surface has any finer perforations. Be sure to under- stand the relation of the live animal to the shell. (Refer to Calkins, pp. 71-78, for a general discussion of the shells of the Sarcodina. ) Make drawings of several types of shells. ACTINOSPHAERIUM OR ACTINOPHRYS. Find, as usual, with the low power, and increase the magni- fication as occasion demands. 1. Note the many fine radiating pseudopodia. These are quite stiff compared with those of Ameba and for a considerable time show little change, not being pushed out and retracted constantly asin Ameba. Is the animal flat or spherical? 2. Both ectoplasm and endoplasm are so filled with vacuoles that they present a frothy appearance characteristic of most Heliozoa. The endoplasm of all Protozoa is alveolar in struc- ture, but in Actinospherium the vacuoles are exceptionally large, though not as large as those in the ectoplasm. 3. The nucleus is present in the center of the organism, but it is somewhat difficult to demonstrate in the live animal. 4. At some point near the periphery, the contractile vacuole can usually be seen. When it is found notice its action, and immediately after it has contracted look among the pseudopodia of that region for indications of its extruded contents. Draw a specimen, indicating all of the points observed. 5. When the contractile vacuole discharges, or when any foreign body touches the ends of the pseudopodia, notice the way in which this type of pseudopodium is moved. What does this indicate in regard to its structure? How far do the pseudo- 6 PROTOZOA. podia extend? They may be seen to contain minute granules when studied with the high power and best hght. 6. If possible, observe the process of catching food with the tips of the pseudopodia and the manner in which it is drawn toward the body. Note any motion on the surface of the body as the food is drawn closer, and also the manner in which the food is finally ingested. Are there any indications that the pseudopodia extend as still finer filaments beyond the point to which it is possible to trace them with the highest magnifica- tion at hand? If the capturing of food is observed, make a series of diagrams to illustrate the process. If possible, observe a specimen undergoing division. Draw. It is desirable to examine Clathrulina, noting the stalk and skeleton. Look over figures. MASTIGOPHORA. EUGLENA, Understand its habitat and with what forms it is usually associated. 1. Observe the free-swimming movements of the organism, and the euglenoid changes in the form of the body. . Make drawings showing the changes in the shape of a single in- dividual. 2. Distinguish anterior and posterior ends. Is there any dorso-ventral differentiation? Note the motile organ, the flagel- lum. Where is it attached? What relation does it bear to the gullet? How is it directed during locomotion of the organism. Does it serve any other purpose besides locomotion? 3. The green color of Euglena is due to chlorophyl, and this enables the animal to live in the clearest water, being nourished like a typical green plant, but minute particles of food are also taken into the endoplasm through the gullet, and thus Euglena combines holozoic and holophytie methods of nutrition. Consider the bearing of this on the position of Euglena and its allies in the protozoan scale. VOLVOX. 7 4. Note the absence of color near the anterior and posterior ends of the organism. Near the anterior end also notice the red pigment spot, or stigma. What is its probable function? 5. Stain a specimen with iodin and look for the nucleus. It is obscured by the chlorophyl. Make a drawing showing all of the points observed. Look through the stock cultures for other forms of Masti- gophora, such as T’rachelomonas, Peranema, Phacus, ete. It is desirable to make drawings of the different forms. VOLVOX. Volvox globator is better for study than V. aurens. It may be distinguished from the latter by the larger size of the colony, the greater number of cells that compose it (about 15,000), the angular shape of the individual cells, and the stout connecting processes of protoplasm, into which chromatophores may enter. Observe the movements of colonies in a watch-glass of water, with the naked eye and with a low power of the microscope. 1. Do the colonies tend to collect toward a particular side of the dish? What reason is there for the reaction? 2. Place a number of colonies on a slide with enough water to allow them to be covered without crushing them. Study first with the low and then with the high power and determine the species. Understand the relation of the individual cells to the colony. (See Parker and Haswell, Fig. 50.) Draw a figure showing several cells and their protoplasmic con- nections. 3. Compare in detail an individual cell with Huglena. 4. Observe, if possible, certain cells, called parthenogonidia, which are specialized for asexual reproduction. These divide and form the daughter colonies, which become detached and swim in the interior of the parent colony. They are finally liberated by the rupture of the wall of the parent colony. Make a figure of a parent colony that incloses several daughter colonies of different sizes. 8 PROTOZOA. 5. V. globator is moneecious. Look for eggs and bundles of spermatozoa. Figure them. 6. Be sure to recognize the significance of the fact that the cells of Volvox are differentiated into somatic and germ cells, and to understand the resulting physiological division of labor. (See Calkins, p. 232.) 7. Consider the reasons for and against regarding Volvox and allied organisms as animals rather than plants. CERATIUM. 1. Examine this form with a high power, and in a favorable specimen notice the sculptured outer surface of the cellulose test. The living animals are green or brown owing to the pres- ence of chromatophores in the protoplasm. 2. Note the furrow encircling the body. Does it extend completely around it? Is there a short furrow on one side at right angles to the first, or a depression of considerable size? Understand the position of the flagella. Draw the animal, showing the points observed. Look for examples of the earlier stages of division, and of later stages, which appear as chains of fully formed individuals attached together. NOCTILUCA. If living specimens are not to be had for study, material preserved in alcohol, after suitable fixation, can be used. Spec- imens are best examined in a cell-slide under a cover-glass. 1. Observe the nearly globular shape, and on one side a groove from which arises a large flagellum or “tentacle.” Is there a deep groove near it?) At the bottom of this groove it is possible to see the mouth in a living specimen. Another smaller flagellum is visible in living specimens inserted at the bottom of the mouth, but in preserving the organism it is usually destroyed. 2. Note the appearance of the preserved protoplasm. The endoplasm appears parenchymatous. At one point a more com- ee GREGARINA. 9 pact mass is seen, from which strands appear to radiate. This has been found to contain the nucleus. Noctiluca is phosphorescent, and frequently causes very bril- liant displays. Make a drawing. SPOROZOA. GREGARINA. Remove the head and posterior end of a larval or adult meal beetle and pull out the digestive tract with a pair of for- ceps. Place the digestive tract on a slide, split it open length- wise with a sharp scalpel, and then spread it out, with the inner wall exposed, and cover. The operation should be per- formed rapidly to prevent the material from drying. If the beetle is infected, numerous gregarines will be visible under the microscope. Study with low and high powers. 1. Does the animal move? A great number of refractive granules are present in the protoplasm. They are regarded as reserve nourishment. ‘They can be removed with acid. 2. Note that the body is covered with a membrane, and is divided into a dense superficial layer, the ectoplasm, and a cen- tral, more fluid mass, the endoplasm. 3. The endoplasm is separated into two parts by a portion of the ectoplasm. The anterior part is termed the protomerite, and the posterior part the dewtomerite. In which is the nucleus situated? 4. Is it possible to distinguish a layer of myonemes just ex- ternal to the endoplasm? 5. Is there another section of the body just anterior to the protomerite? If so, this is the epimerite. Before reproduction Gregarina throws off the epimerite, leaves it in the cell-host, and falls into the lumen of the digestive tract. It then encysts, and the protomerite and the deutome- rite form one spore-producing individual. The attached stage in the life-history of Gregarina is termed the cephalont, and the detached stage, the sporont. (See Calkins, Fig. 77.) Make a drawing. 10 PROTOZOA. INFUSORIA. PARAMECIUM. Place a drop of the culture on a slide, cover, and examine with the low power. 1. In an animal not closely confined note the shape and movements. Is it possible to distinguish an anterior and a posterior end? A forward and backward movement? Is one side of the animal kept constantly uppermost? Is there a dorsal and ventral surface? Do the animals change their shape either permanently or temporarily? Individuals tend to collect about air-bubbles and at the edge of the cover-glass. Why? Indicate by a sketch all the points which can be determined with the low power. 2. Draw off all superfluous water by means of filter-paper, add a trace of powdered carmine, and then find a specimen which is narrowly confined and examine it with the high power. The particles of carmine are taken into the body. Deter- mine how and where. Note that the carmine collects in gastric vacuoles. What do you think is probably the nature of the fluid in the vacuoles? In watching them do you notice any definite movement of the protoplasm? Try to see the undi- gested material ejected. 3. Determine the arrangement of the cilia, and the nature of their motion. Is there a reversal of the direction of the stroke, etc. ?* 4. Observe the contractile vacuoles. How many are there? Is their position constant? What is their action? In com- pressed specimens the contractile vacuoles and their reservoirs are usually conspicuous. Note the order of appearance and disappearance of the vacuoles and reservoirs. 5. Focus carefully on the margin of the body and note a very thin outer cuticle. A thick layer, the ectoplasm, devoid of gran- ‘It is possible to decrease the rate of movement of both animal and cilia by placing it in a solution of gum arabic. Specimens so treated remain alive for some time. —— eer ee SPIROSTOMUM. VORTICELLA. 11 ules but containing radially arranged, minute, oval bodies, the trichocysts, is just internal to the cuticle. The inner mass of protoplasm, containing the contractile and gastric vacuoles, and small granules, is the endoplasm. 6. If possible distinguish the clear, centrally located nucleus (macronucleus). Make a sketch showing all oj the above points. 7. Kill the animal by running a drop of methyl-green under the cover-glass. What happens to the cilia? To the trichocysts? Sketch the trichocysts with the threads protruded, and also note and sketch the macronucleus and the micronucleus. 8. Observe, if possible, animals dividing and conjugating. 9. Study demonstrations of permanently stained specimens for finer structure. SPIROSTOMUM. 1. Compare Spirostomum with Paramecium, noting the method of locomotion, the shape of the body, the ciliation, the buccal groove and mouth, and the large excretory reservoir, fill- ing the posterior end of the body and in communication with the anterior end of the body by a canal. 2. Note the highly refractive, long, band-like (monilijorm) macronucleus. In another species of Spirostomum the macro- nucleus is similar to that of Paramecium. It is desirable to examine stained specimens of the two species of Spirostomum. 3. Note the sudden contractions of the body. When these occur spiral lines appear on the surface. Can you distinguish these lines when the animal is extended? These are primitive structures (myonemes) functioning as muscles. Make a drawing of the extended animal and a diagram shou- ing the form when contracted. VORTICELLA. Place a number of individuals on a slide and cover loosely to avoid crushing. As usual, study first with the low power and then with the high. 1. Notice that the body of Vorticella has the general shape 12 PROTOZOA. of an inverted bell. The covering of the body is a very thin transparent layer, the cuticle, underneath which is the periphe- ral layer of ectoplasm enveloping the more fluid and granular endoplasm. 2. The peristome is the rounded rim about the base of the bell. 3. The elevated and inclined area included within the peri- stome, and ciliated around the edge, is the disk. It is some- what convex. 4. The marked depression between the disk and the peri- stome is the vestibule. It is also lined with cilia. The vestibule defines the ventral surface of the animal. 5. The guilet, a slender canal, leads from the vestibule toward the center of the body. 6. The anus occurs at the side of the vestibule. It is a tem- ‘porary opening from which the undigested products are passed into the vestibule and so to the exterior. 7. Within the endoplasm are situated the clear contractile vacuole, several gastric vacuoles, the long U-shaped macronucleus, and the small round micronucleus. The macronucleus may be made more distinct by treating with methyl-green. 8. The stalk is composed of a sheath, which is continuous with the cuticle of the body, and, within the sheath, the contractile axis or myoneme, which is continuous with the body ectoplasm. Notice that this myoneme is situated within the sheath in a very loose spiral, and that the stalk quickly contracts into a close spiral when the animal is stimulated. Observe also the manner in which the peristome folds over simultaneously with the contraction of the stalk. What purpose does the contrac- tion of the stalk serve? Vorticella is distinguished from its allied genera by its sim- ple unbranched stalk and also by the spiral form assumed by the contracted stalk. In which order of the Ciliata does the cilia- tion of Vorticella place it? Make a drawing of an expanded individual and a sketch to show the condition when contracted. 9. Study, by means of finely powdered carmine, the vortex OXYTRICHA. 13 currents set up by the cilia. Note how the particles are collected in the gullet, and at intervals are forced in rounded masses into the endoplasm to form gastric vacuoles. Is there a definite circulation in the endoplasm? 10. Endeavor to find several stages of reproduction by divi- sion. Large fresh-water species of Vorticella are preferable for study, but marine species may be substituted when necessary. If time and material permit, study Lichnophora, a marine peri- trichous form parasitic on Crepidula. (See Calkins, p. 208.) OXYTRICHA, Infusoria belonging to the genus Oxytricha, or the genera Stylonychia, Pleurotricha, Euplotes, etc., may be used for the following study. ‘These forms belong to the order Hypotrichida. Hypotrichous forms are the most highly organized of the class Infusoria, as well as of the entire phylum of Protozoa, and pre- sent a complexity of structure and function which is not found probably within the limits of a single cell elsewhere in the animal series. 1. In an animal which is becoming quiet, note the mode of locomotion, the shape of the body, the buccal groove, the con- tractile vacuole, etc., as in other forms studied. Compare the ciliation with that of other forms. Refer to Calkins, Fig. 98, and understand the relation of cirri, membranelles, ete., to cilia. Draw, showing the structure in detail. 2. Run some methyl-green under the cover-glass. What is the shape of the macronucleus? The shape varies considera- bly in the different genera. Is it possible to distinguish the macronucleus? 3. Prepare a fresh slide and observe in detail the character- istic movements and manner of creeping over various objects. As the animal turns sidewise, note the marked dorso-ventral compression of the body. Represent this diagrammatically beside the previous drawing. It is desirable to examine permanently stained preparations for division stages, finer details of the nuclei, etc. PORIFERA. Cells not differentiated to form definite organs. Water admitted through surface pores and ejected through an osculum or through oscula. Ciass 1. Calcarea. With a skeleton composed of calcareous spicules. Subclass 1. Homoccela. With the gastreal layer continuous so the col- lar cells line the whole gastreal cavity. (Leu- cosolenia. ) Subclass 2. Heteroccela. Gastreal layer discontinuous. Collar cells restrict- ed to the flagellated chambers. (Grantia.) Cuass 2. Hexactinellida. With a skeleton composed of siliceous six-rayed spicules. Order 1. Lyssacina. Spicules separate or becoming united. (Euplec- tella.) Order 2. Dictyonina. Spicules united from the first into a firm frame- work. (EKurete.) Ciass 3. Demospongie. Great diversity of structure. Dominant forms of today. Subclass 1. Tetraxonida. _ Typically with four-rayed spicules. (Corticella.) Subclass 2. Monaxonida. Simple, usually unbranched spicules. Spongin frequently present. (Cliona, Suberites, Chalina, Spongilla.) Subclass 3. Keratosa. Skeleton of spongin fibers. No true spicules. (Euspongia, Aplysina.) Subclass 4. Myxospongida. Without skeleton. (Oscarella.) 14 GRANTIA. 15 GRANTIA. This form is quite common along the New England coast, where it occurs attached to rocks, seaweeds, and submerged woodwork from just below the lowest tide-mark to a number of fathoms in depth. You should visit an old wharf where speci- mens may be found, and study their relation to the forms with which they are associated. Specimens will be found to vary considerably in size. The largest sometimes reach an inch in length. 1. Examine a dry specimen and notice its general shape, manner of attachment, and osculum. The osculum is surrounded by a funnel of rather long spicules. Distributed over the gen- eral surface, more or less hidden by the numerous spicules, are many small pores. Their presence may be demonstrated more satisfactorily later. 2. Look for indications of budding. If your specimen does not show this, examine others. Make an enlarged drawing of a sponge. With a razor or sharp scalpel cut a dry specimen into halves, with a stroke from base to osculum, and notice: 3. The central cavity or cloaca. 4. Many apopyles, the inner openings of tubes that are em- bedded in the walls of the sponge, will be seen opening into the cloaca, Are the apopyles arranged in any order? 5. With the low power of your microscope (with the light turned off) examine the cut wall and find that it is traversed by parallel tubes. Determine that these tubes are of two kinds. (a) Regular, nearly cylindrical tubes that open into the cloaca through the apopyles and that bear tufts of spicules on their closed ends, at the surface of the body. These are the radial canals. It is frequently hard to see their openings into the cloaca, as the apopyles are narrow, so the section only occa- sionally passes through them. (b) Smaller and less regular tubes that open on the outer surface between the clusters of spicules, and do not open into 16 PORIFERA. the cloaca. These are the incurrent canals. In life there are small pores, prosopyles, that open from the incurrent canals into the radial canals. These openings are very minute and are apparently capable of being closed. They are never visible in dried material. 6. Examine thin, transverse sections of a dry sponge and determine the positions of radial and incurrent canals. Make a drawing that will show the arrangement of the canals. 7. Examine the spicules and determine their positions as regards canals. Boil a portion of a sponge in caustic potash until only the spicules remain and examine the spicules. See if more than one kind occurs. Draw specimens of the spicules. LIVING AND SECTIONED MATERIAL. 1. Place a living sponge in a watch-glass of sea-water, add a little powdered carmine, and examine it with the low power of your microscope for currents of water. See if particles are mov- ing in a definite direction near the general surface and near the osculum. 2. With a moderately sharp razor cut tangential sections of the wall, as thin as possible, mount in sea-water under a cover, and examine with a low power. This will show both incurrent and radial canals in cross-section. How can you distinguish one from the other? In a favorable place look for moving flagella. Are flagella in all of the canals? In favorable situa- tions it can be easily seen that the cells that have flagella possess collars also. (Collars may be withdrawn by cells so they pro- trude but slightly.) You see now what causes the current of water. Do you understand how a sponge feeds? Compare the. choanocytes of the sponge with choanoflagellate protozoans. Make a drawing showing the arrangement of choanocytes. Examine transverse sections.of a specimen that has been decalcified and stained. 1. The cloacal chamber is lined by a pavement of epithelium. 2. The radial canals are lined by more conspicuous cells, the gastral epithelium, or choanocytes. GRANTIA. 17 3. The incurrent canals and the outer surface of the sponge are covered with flattened cells, the dermal epithelium. 4. In a part of the section where a considerable area of choan- ocytes appear in surface view, look for the prosopyles, through which the water passes from the incurrent to the radial canals. (They may not be found.) 5. Make out any structures you can in the area lying between the dermal and gastreal layers. What cells are found here? Make a drawing of several adjacent canals to show the above points and indicate the course of the water by arrows. 6. In the stained sections, look for single ova and for spheres containing many spermatozoa, the sperm-spheres. Look also for segmenting eggs, which are frequently to be found. The ova are fertilized while still lying where they have developed, just within the choanocyte layer. Remaining in place, they undergo cleavage and develop so far as the amphiblastula stage (see figures in the text-books). They then break through the choanocyte layer into the radial canals and pass out with the current of water. Living specimens are frequently found with such embryos issuing from the osculum in the outgoing current of water. The sperm-spheres, when fully developed, also break through the choanocyte layer and, separating into their com- ponent spermatozoa, pass out with the outgoing water. Ova and sperm are present in the same individual, and the ani- mal is therefore hermaphroditic. Whether self-fertilization is pre- vented, as in many other hermaphroditic forms, by the ripening of one element before the other, has not been fully established. Ij the time allows, draw ova, sperm-spheres, segmenting eggs, and embryos. It is desirable to examine specimens of Lencosolenia, a still simpler sponge, and of some of the more complicated forms, like commercial sponges, Spongilla, Cliona, and Chalina. Why is more than a single osculum desirable in such forms? Under- stand the relation of the internal structure of the complicated forms to the more simple forms. What reason is there for the complication? 2 COELENTERATA. With a single continuous ccelenteron or gastro-vascular cayv- ity. With the exception of the Ctenophora all have nettle cells. There are two cellular layers and a mesoglea. Cuass 1. Hydrozoa. Ccelenteron simple, without septa. Gonads usu- ally ectodermal. Fully formed medusze have a velum. Order 1. Leptoline. With a fixed zodphyte stage. Suborder 1. Anthomedusz. Without hydrothece or gonothece. The medusa bears gonads on the manubrium. (Hydra, Pary- pha.) Suborder 2. Leptomedussze. With hydrothece and gonothece. The medusa bears gonads on the radial canal. (Obelia, Goni- onemus. ) Order 2. Trachyline. Without fixed zoophyte stage. Suborder 1. Trachymeduse. Tentacles from the margin of the umbrella. Gonads on the radial canals. (Petasus.) Suborder 2. Narcomeduse. Tentacles from the exumbrella. Gonads on the manubrium. (Atginopsis.) Order 3. Hydrocorallina. Massive calcareous exoskeleton. (Millepora.) Order 4. Siphonophora. Pelagic. Colonial. Colony usually shows extreme polymorphism of its zodids. (Physalia.) Ciass 2. Scyphozoa. Body-wall of polyp thrown into four ridges (tzeni- oles) which project into the ccelenteron. Medusz without velum and with gastric tentacles. Medusoid form predominating. 18 CCELENTERATA. 19 Order 1. Stauromedusz. Conical or vase-shaped umbrella. No tentacu- locysts. (Tessera.) Order 2. Peromeduse. Conical umbrella with transverse constriction. Four inter-radial tentaculocysts. (Pericolpa.) Order 3. Cubomedusz. Four-sided umbrella. With per-radial tentaculo- cysts. (Charybdea.) Order 4. Discomeduse. Saucer-shaped umbrella. Per-radial and inter- radial tentaculocysts. (Aurelia.) Cuass 3. Actinozoa. With a stomodzeum, and with mesenteries ex- tending into the ccelenteron. Fixed forms. Subclass 1. Zoantharia. Mesenteries and tentacles usually very numerous. Order 1. Actiniaria. Usually single. No skeleton. (Metridium. Sa- gartia.) Order 2. Madreporaria. Usually form colonies and always have calcare- ous exoskeleton. (Astrangia, Orbicella, Mean- drina. ) Order 3. Antipatharia. Tree-like. Mesenteries and tentacles compara- tively few. Chitinoid skeleton. (Cirripathes.) Subclass 2. Alcyonaria. Mesenteries and tentacles eight in number. Ten- tacles branched. Order 1. Aleyonacea. Skeleton in the form of small, irregular bodies, frequently calcareous spicules. (Aleyonium, Tubipora.) Order 2. Gorgonacea. Tree-like, with calcareous or horny exoskeleton. No syphonoglyphes. (Gorgonia.) Order 3. Pennatulacea. Colony with one end usually embedded in the sea-bottom. (Pennatula, Renilla.) Ciass 4. Ctenophora. Single. Pelagic. Eight rows of meridional swimming plates. No nettle cells. 20 CCELENTERATA. Order 1. Cydippida. Nearly circular. Two tentacles, each of which may be retracted into a sheath. (Pleurobra- chia, Mnemiopsis.) Order 2. Lobata. Compressed in the vertical plane. Two large oral lobes. No tentacle-sheaths. (Deiopea.) Order 3. Cestida. Ribbon-shaped. Two tentacles with sheaths, and numerous other tentacles. (Cestus.) Order 4. Beroida. Laterally compressed. Without tentacles. (Berce.) HYDROZOA. HYDRA. (Fresh-water Polyp.) Hydra, the only common fresh-water ccelenterate, is fre- quently found in jars of water taken from quiet pools or sluggish streams that contain lily-pads, decaying leaves, and other vege- table matter. The animals may frequently be found by examin- ing the surfaces of submerged leaves, but it is usually better to allow such material to stand in glass jars for a day or two, as the animals then tend to collect on the lighter sides of the vessels. They are easily kept in balanced aquaria. Examine specimens in an aquarium and find what you can about their mode of life. Do they form colonies? Place a specimen in a watch-glass of water and examine it with a lens. 1. What is its shape and color? Is it attached? If so, by what part of the body? Notice the circlet of tentacles. How many are there? Compare notes with others and see if all have the same number. How are they placed? 2. Does the Hydra move its body or tentacles? Is it sensi- tive? How do you know? 3. Examine with a low power of the microscope and review the above points. You may also be able to see the mouth around which the tentacles are arranged. HYDRA. a Make two drawings, one showing the animal expanded and the other contracted. Place your specimen on a slide under a cover-glass that is supported by the edge of another cover-glass, so it can be exam- ined with a high power. Be careful not to crush it. Notice: 4. The outer layer, ectoderm. What is its color? Is it continuous over the whole outer surface? Does it vary in thick- ness? Are the cells of which it is composed apparently all alike? 5. The inner layer, endoderm. What is its color? If color is present, is it evenly diffused or is it collected in special bodies? Are the cells of which the endoderm is composed apparently all alike? Do they differ in appearances from those of the ecto- derm other than in color? If the specimen is not deeply colored, look for flagella moving in the internal cavity. 6. Examine the ectoderm of the tentacles carefully and notice that each of the large, rounded, clear cells, the nematocysts, shows a rather indefinite streak running from its outer end, back into the interior. See if you can find the trigger (enidocil) on any of these cells. Draw a portion of a tentacle showing the distribution oj the nematocysts. 7. Place your specimen under the low power of the micro- scope, carefully run in a drop of saffranin, and see if any of the nematocysts are discharged when the saffranin touches them. Examine with a high power and notice the appearance of the thread. Notice the change in the shape of the nematocysts that have discharged. See if you can find two kinds. Make an enlarged drawing of an exploded nematocyst. 8. Examine prepared transverse sections of Hydra. Notice that the body is composed of two layers of cells, between which is an almost structureless thin layer. Do the cells of the two layers differ in size, shape, and structure? Do you find more than one kind of cell in each or either of these layers? Where are they? What are they? Make a careful drawing of the section showing the arrangement as you see it. 22 CCQELENTERATA. Examine longitudinal sections, for differences in the char- acter of the ectoderm and endoderm in different parts of the body. 9. Reproduction. Examine living specimens in a watch- glass of water for bud formation and for sexual organs. Sperm- aries are just beneath the tentacles; ovaries, lower down; buds may be found at different levels. What layers of cells is involved in the formation of each of these? Eggs are not formed at all seasons of the year and vary greatly in appearance according to their stage of development. Make drawings of the stages of reproduction that you find. OBELIA. These small, colonial animals are. common on submerged or floating wood, stones, and seaweeds, where the water is rather free from sediments. With the aid of a glass-bottomed pail they, in company with many other forms, may usually be seen about old wharfs. Note the appearance of large colonies of this form that are growing on stones or on pieces of board. 1. Notice the tree-like form of any single stem. Do the branches have a definite size and arrangement? 2. At the extremities of the branches are the single individuals, hydranths or zodids. Each is similar to a single Hydra in cer- tain ways, but is inclosed in a vase-like formation, the hydrotheca. 3. The latter is a continuation of a tough, membranous sheath, the perisarc, which covers each part of the whole colony. Do you notice any modifications of the perisare below the hydrotheca? Do the modifications serve any purpose? 4. Trace the stem down to the creeping, stolon-like portion of the colony, the hydrorhiza. Make a drawing of a colony. 5. The fleshy continuation of the zodid down into the stalk is termed the cenosarc. Is it in close contact with the perisare? 6. In an expanded hydranth, note the mouth, the arrange- ment of the tentacles, and the number of tentacles. How is the OBELIA. 23 individual supported in its cup? Can you trace the celenteric cavities down through the stalks, and prove them to be continuous with each other? Motion in the fluid contents of living speci- mens makes this easy to observe. 7. Examine a hydranth with a high power and look for the cell-layers characteristic of ccelenterates. Determine how its tentacles differ from the tentacles of Hydra, and explode nemato- cysts as with Hydra. Make a drawing of a hydranth. 8. Look for certain extremities which show neither tentacles nor any opening in the perisarcal covering. Such a condition signifies either an undeveloped hydranth or a reproductive individual. If the latter, it is considerably swollen and is termed agonangium. ‘The central core or coenosarce of a gonangium, the blastostyle, should be examined for medusew buds. This may re- quire a high power. Make a drawing of a gonangium. 9. You may find free medusze swimming in the dish where material is kept. If you do, you should examine one, but it will not prove as satisfactory for study as a larger form, like Gonionemus, directions for the study of which are given further over. In comparing it with Gonionemus notice the small size of the velum, and the ease with which the bell turns wrong side out, so the manubrium appears like a handle. At Woods Holl, Obelia apparently does not always liberate its medusz, and it is not uncommon to find planule escaping from gonothece. Frequently those medusze that are liberated have previously shed their eggs. 10. Study the cellular structure of a hydranth and of a gon- angium, as seen in cross and longitudinal sections. Make a drawing of each. For comparison use any thecate forms, which may be offered as loose material or as demonstrations, such as Campanularia, Sertularia, and Plumularia. 24 CCELENTERATA. PARYPHA. This form is frequently abundant on the piles of old wharfs, where the colored colonies form conspicuous masses just below low-water mark. Examine the general form of a colony and note, either with a hand lens or with the naked eye, the stem, or hydrocaulus, as it arises from the branching, matted hydrorhizal portion of the colony. The parts of the colony will be seen to differ from the Leptomedusan (Campanularian) form studied, especially in branching, rigidity, hydrothece, and gonangia. Make a drawing to show the formation of the colony. 1. How does a hydranth differ from the hydranth of Obelia in the matter of tentacles? Is a hydrotheca present? 2. The mouth is terminal and is situated at the end of a manubrium. 3. The short but rather large body of the hydranth passes back to the perisarc as the fleshy axis, cenosarc. 4. Notice the medusa buds on the manubrium between the rows of tentacles. What is their arrangement? This is a form in which the medusz are not set free, but remain vestigial. The gonads ripen on the partially developed manubrium of the medusa. The sexes are separate. Make a drawing of a hydranth. 5. The arrangement of the attached meduse& is best seen in sections. In the male meduse numerous spermatozoa will be found, while the female individuals have a much smaller number of large ova, which are likely to be in advanced stages of seg- mentation. The sections show the same body layers as Hydra, and the derivation of the medusa as an outpocketing of the wall of the hydranth is evident. Make drawings of sections of male and female reprogaeeiae organs (medusa buds). For comparison, study Pennaria, Margelis, Hydractinia, Clava, and Eudendrium. GONIONEMUS. 25 GONIONEMUS. As has been seen, the medusze buds are usually produced from the walls of a specialized hydranth (Leptomedusz) or -from the manubrium wall of an ordinary hydranth (Anthomeduse). A series of these buds in various stages would show the formation of the umbrella-shaped individual with the growth of the marginal tentacles around the edge. ‘The life-history of this form is not known, but from its structure we are led to believe that it belongs to the suborder Leptomedusz.’ It is found in con- siderable numbers throughout the summer in the border of eel- grass in the Eel Pond at Woods Holl, where it may be obtained with adip-net. It is more satisfactory to study than the medusa of Obelia, as it is much larger and its movements and organs are more easily observed. In plan of structure the two are quite similar. Put a living specimen in a flat-sided jar containing sea-water, or in a finger-bowl, with a black tile beneath, and notice: 1. Its method of locomotion. To the contraction of what part of the bell is movement due? How large is the jet of water that is delivered from the bell? Why is the jet made narrow? Does the jet necessarily leave at the center or may it be thrown from one side? Should it be thrown from one side, what would be the result? 2. Its position in the water when quiet. Why is this position more desirable than the opposite? With a needle-point prove that various parts of the body are sensitive. With either fresh or preserved material notice: 1. Its flattened dome-shape. The convex face is called the ex-umbrella (aboral), while the concave portion is termed the sub-umbrella (oral). 2. The velum is the perforated diaphragm that partly closes in the sub-umbrella. All medusz possessing this structure are classed as Craspedota. Do you understand its use? 1There is some reason for thinking that the polyp stage of this form develops directly into the medusa. (See Perkins, Proc. Acad. Nat. Sci., Philadelphia, 1902.) 26 CCELENTERATA. 3. In the center of the sub-umbrella is seen the large pen. dent manubrium, at the extremity of which is a wide-lipped mouth. If the medusa is alive, feed it with small bits of clam meat. 4. From the capacious sac at the base of the cavity of the manubrium, the stomach, the four radiating chymiferous tubes, or canals, lead to the periphery of the disk, where they open into the very delicate circular circumferential canal. The four radii marked out by these canals are called the per-radu. Do you understand the use of these canals? 5. The gonads hang from beneath the chymiferous tubes into the sub-umbrellar space. They are lobulated in structure, and more or less prominent according to maturity and the breeding season. The eggs or spermatozoa, as the case may be, are de- hisced from these into the water directly. 6. The tentacles. Is their arrangement a radially symmetrical one? How are the nematocysts arranged on them? Look for adhesive organs on them. Of what use are such organs? Turn your specimen with the velum side toward you and study the edge of the medusa with a low-power objective for the sense organs. These are of two kinds: (a) The larger, round bodies at the bases of the tentacles communicate with the circumferential canal (which may possibly be seen along the edge of the bell). They are filled with a layer of strongly pigmented endoderm cells and are probably light- perciprent organs. (b) Other small sessile and transparent outgrowths, situated between the bases of the tentacles, are the so-called otocysts, which are probably static organs. All of the tentacles are abundantly supplied with tactile, sensory cells. There is a well-established circumvelar nerve ring (not easily determined in living material) derived from the ectoderm, also scattering nerve cells beneath the ectoderm in connection with the muscular tissue. Ex-umbrellar and sub- umbrellar layers of muscle fibers are also present. HYDROCORALLINA. SIPHONOPHORA. AURELIA. Ze Make a drawing from the side, slightly tipped, to show the velum, and another as seen from the oral surface. HYDROCORALLINA. To this group belong forms that have heavy calcareous exoskeletons. While material is generally not at hand to study the polyps, it is desirable to study and sketch the characteristic forms of colonies such as Millepora and Stylaster, and to note the difference in the distribution of pores. Later you will see how decidedly these differ from the ordinary stony corals. SIPHONOPHORA. Examine living or preserved specimens of Physalia, and sketch the type with reference to showing, if possible, the follow- ing structures: (a) pneumatophore, (b) dactylozodids, (c) gastro- zodids, (d) gonodendrons, (e) tentacles. It will be well to refer to a text-book to find the positions and functions of each of these. SCYPHOZOA. AURELIA. This form is one of the common jelly-fishes, and is found floating freely in the water. It is frequently washed up on shore. To be appreciated these medusz should be seen as they occur at the surface of the sea, before they have been handled or in- jured. Frequently vast numbers may be seen together, all gently pulsating and thus keeping near the surface. The move- ment is very different from that of most hydrozoan medusa, being very deliberate and graceful. If living material is offered, study the method of locomotion and compare it with the locomotion of Gonionemus. Like the latter, the discoid animal presents ex-umbrellar (aboral) and sub- umbrellar (oral) surfaces, but the edges of the disk are indented, fringed with very numerous short tentacles, and a velum is wanting. What difference does the velum make in locomotion? The ex-umbrellar surface presents little of interest. In the 28 CCELENTERATA. live specimens, however, prove that the animal is sensitive over this area as elsewhere. Preserved and hardened material is better than living for the study of the rest of the anatomy of this form. With a specimen in water in a finger-bowl, with a black tile for the background, find the following from the sub-umbrellar surface: 1. The shape of the animal. Is the margin perfectly circular or regularly indented? Are all of the marginal portions similar? 2. Four large, fringed oral arms or lips hang from the corners of the nearly square mouth, which is located in the center. No- tice how each arm is similar to a long, narrow leaf, with the sides folded especially along their margins. Examine the arms for nematocysts. Do you understand how the animal gets its food? If the arm edges appear to be covered with dark specks and granules, examine to see if embryos may not be entangled. 3. The mouth is found to lead by a short gullet into a rather spacious stomach, which is produced in the region between each two corners of the mouth to form a gastric pouch. Determine the shape of the stomach. 4. The remaining parts of the digestive (and also in this case circulatory) system include the numerous radial canals and the single circumferential canal. (a) Directly beneath each oral arm a per-radial canal is given off, which, at a short distance from the stomach, gives off a branch on either side. The per-radial canal proper usually continues straight to the marginal circumferential canal, without further subdivision, but the two side branches above mentioned in turn subdivide several times. (6) From the peripheral wall of each gastric Be three canals pass toward the margin; the middle one (inter-radial canal) branches somewhat after the manner of the per-radial canals, but the other two (ad-radial canals) continue to the circular canal without further branching.’ 1In most cases the foregoing canals are very evident, but if they are not, they may be injected w ‘ith water in which carmine is mixed, by insert- ing a large-mouthed pipet into the stomach. AURELIA. 29 5. The position of the gastric pouches is made clearly mani- fest by the gonads, which lie on the floor of the pouches, as frill- like structures, horseshoe-shaped, with their open sides toward the mouth. The ova or spermatozoa are shed into the stomach and pass out of the mouth. Embryos in various stages of develop- ment may frequently be found adhering to the oral arms. The sexes are separate. On the sub-umbrellar surface, opposite each gonad, is a little pocket, the sub-genital pit, which opens freely to the outside. Whatever purpose this may serve, it does not function to conduct the genital products to the outside. 6. Parallel with the inner or concave border of each gonad is a row of delicate gastric filaments. These are supplied with stinging cells, and they may aid in killing live food taken into the stomach. These structures are not present in the Hydro- zoan medusa. 7. At the marginal extremity of each per-radial and inter- radial canal there is an incision on the edge of the animal, in which there are sensory organs. In each incision find: (a) A tentaculocyst in the form of a short, club-like struc- ture containing a prolongation of the circular canal. At its outer extremity are calcareous concretions or lithites, and a pig- ment-spot or ocellus. Each tentaculocyst is protected aborally by a hood-like projection, and on the sides by marginal lappets. (b) Two depressions, one above and the other below the tentaculocyst. These have been assigned olfactory functions, and are called the oljactory pits. Make a drawing showing the profile of the entire animal, and show the structure of at least one quadrant, as seen from the oral surface. If time permits study a developmental stage, “‘ephyra,” and compare it with the adult. By way of comparison, examine demonstrations of Cyanea, Dactylometra, Lucernaria, or other forms belonging to this group. 30 CGELENTERATA. ACTINOZOA. METRIDIUM. (Sea-Anemone.) Specimens are quite common on piles, as well as on rocky bottoms, and may be easily observed by means of a glass- bottomed pail. Most of the observations can be made much better on specimens in aquaria, but it is desirable to see their natural surroundings. 1. Notice the shape and attachment of expanded, living speci- mens in an aquarium, or in a deep finger-bowl. The free end, called the disk or peristome, is fringed with tentacles, and the elongated mouth is located in the middle of this area. At one or both angles of the mouth the lips are thickened into what is called a stphonoglyph. Make a drawing of the animal. 2. Feed a specimen with bits of mashed clam to ascertain its manner of taking in food. Drop bits on the tentacles at one time, and disk at another. Endeavor also to determine whether there are currents constantly passing in or out of the mouth that are due to-ciliary action. 3. Irritate the animal and observe its manner of contraction. When fully contracted, if the irritation is continued, thread- like structures, acontia, are thrust out through minute pores, cinclides, in the body-wall. Make a drawing of the contracted animal. Internal Anatomy.—Using preserved material, place the edge of a razor across the peristomial area, at right angles to the mouth-slit, and divide the animal from disk to base into halves. 1. Note the extent of the esophagus and siphonoglyphes; they lead into the celenteric chamber. Find the extent of this chamber, and the method of its subdivision by delicate parti- tions, the mesenteries, or septa. Are all of the mesenteries alike? 2. Forming the free edges of the mesenteries, below the esophagus, are the convoluted mesenteric filaments, which are METRIDIUM. 31 secretory organs that are probably equivalent to the gastric filaments of the Seyphozoa. 3. Quite near the bases of the mesenteries are the attachments of the acontia. What relation have they to the mesenteric fila- ments? 4. Also located on the mesenteries, and arranged parallel to the filaments, but back from the edge a bit, are the repro- ductive organs or gonads. Are they found on all of the mesen- teries? The ova or spermatozoa are shed into the ccelenteric chamber and pass out through the mouth. Cut one of the halves of your specimen transversely in the region of the esophagus, and study the arrangements of the mesenteries, their attachments, ete. 5. How many pairs of primary mesenteries, i. e., those attached both to the outer body-wall and to the esophagus, are there? The directive septa are those at the angles of the esophageal tube. The portion of the ccelenteric cavity between any two pairs of mesenteries is termed an inter-radial chamber. The space between the two mesenteries of each pair is called an intra- radial chamber. 6. Carefully determine the disposition of the longitudinal retractor muscles on the mesenteries. Do they occupy similar positions on all of the mesenteries ? 7. Examine the upper parts of the mesenteries for openings, septal stomata, that put the chambers in communication 8. Are the tentacles solid or hollow? Make a drawing oj a longitudinal section and another of a cross-section. Put into these all of the points of the anatomy you have seen. If time and opportunity permit, it is very desirable that this form should be compared with specimens of the order Madre- poraria, and later with the Alcyonaria. Such a form as Astran- gia may easily be obtained either alive or properly preserved, and will serve to show the relation of the hard parts of the coral _ to the polyp. You should understand the relation of the septa 32 CCELENTERATA. and the mesenteries, and of the polyps to each other. If speci- mens are at hand, compare such forms as Orbicella, Favia, and Meandrina, or any forms that show gradations from separate calices to fused groups, and understand the positions of mouths, the arrangement of the ccelenteric chambers, and the way in which the colony has come to its present form. You should also examine large branching colonies and determine why branches are formed and how they arise. Examine the structure of an Alcyonarian colony and see how the polyps are placed. The structure of the expanded polyps is nicely shown by Renilla. The spicules of such forms as Gorgonia may be obtained by boiling a portion of a colony in caustic potash. What purpose do such spicules serve? CTENOPHORA. | MNEMIOPSIS. This form belongs to the group of animals popularly called ‘“‘comb-jellies,”’ and occurs along the coast in irregular abun- dance during the summer months. Specimens are very phos- phorescent when disturbed, so, when they are abundant, the display caused by them while rowing at night is sometimes bril- liant. They may frequently be seen during the daytime and can often be satisfactorily observed in the shade of a wharf when the water is calm. Unmutilated, living material can be studied to best advan- tage, but preserved material may be had that is quite satisfac- tory for anatomic study. 1. In general appearance a specimen resembles a hydrozoan medusa, with its aboral surface elongated until, as a whole, it approaches the shape of a fowl’s egg. 2. The broader or oral end bears two heavy terminal lobes, between the bases of which is the slit-like mouth. 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