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OF £ j ' - ' - - ’ 7 : } : . ts a : 1 } 1 - <& 7 f cg 4 ; y ILLINOIS BIOLOGICAL MONOGRAPHS Vol. XIV No.4 PUBLISHED BY THE UNIVERSITY OF ILLINOIS UNDER THE AUSPICES OF THE GRADUATE SCHOOL UrBANA, ILLINOIS EDITORIAL COMMITTEE Joun THreopore BUCHHOLZ FrepD WILBUR TANNER CHARLES ZELENY UNIVERSITY c * OF ILLINOIS 1000—9-36—9359-S 1h PRESS 1: THE LIFE HISTORY OF COTYLOPHORON COTYLOPHORUM, A TREMATODE FROM RUMINANTS WITH NINE PLATES By HARRY JACKSON BENNETT CONTRIBUTION FROM THE ZOOLOGICAL LABORATORY OF THE UNIveRSITY OF [LLINOTS No. 485 DistrrButEp SEPTEMBER 29, 1936 CONTENTS Introduction. Bow ee a eA Oe Be te Le 7 Materials and Methods . . .. . . . . . . 8 History of the Genus Cotylophoron . 9 “Egg 12 OMiracidium. . . . . 1... ee ee ee Development 14 PL Clio ake e ane OL be eh. a, 5, la & 23 Mature Mirdcidium 2, << “ 29 as 4 8 we ew 25 Mintermediate Host.“ .. - 2. - 2. 2. w sie « © « » 88 Determination of the Host . . . . .. ... . 38 Biology of Fossarta parva. . . 1. we 39 SOOMOC st MGs. bP eee ie. Oe. ak tae we lee ee 44 Development .....° . . « « «© « » «© &» +» «© » 44 Mature Sporocyst . «*. «< $ « « «© e026 «6 » Redig@ts WRT 4? ia ek a ke Oe SO ee Wevelopmewt. « wraiaes & © «@ & «a o) “ei ce 54 NMattiretRedia jo 5's & is 2 «© + «~ « » «= weg ~ 9 00 Daughter Redia. “2.0% 4 < 3 «2° « G + <@ Go e « 4. 68 Scrcatiameen ty fa a. ae ee ee SS ee sw «6 Development . . . . . . 2... «we « « . 64 Niatinewercatia’ 2° « 2 4 vat eS Me ee Se Ge OD Discussion of Previously Described Amphistome Cercariae . 76 Wetacercariave's; i 4 -S- Se + & Rb eela¥oew. oo we ue, 18 Nau ny ee ok en en RI. Btn AD Experimental Infestation. . . . . . . . . . . 79 Development. . . . . . ... pa! ake fe A uier OO Specific Description of Cotylophoron espe a th ee. BO Summary and Conclusions .-. = «< &% « = «4 » s 96 Bibliosraphy- 3 « 2 « «© 4» + “8 ese e « «2 » 98 mlatess ee eee a eee ee chr es Se Ow. & OT ACKNOWLEDGMENT This work was begun under the direction of Professor H. B. Ward, now Professor Emeritus of the University of Illinois, to whom I wish to express my appreciation for suggestions in con- nection with this problem. The work was com- pleted under the direction of Professor H. J. Van Cleave, to whom I wish to express my apprecia- tion for his inspiration and encouragement and for his many valuable suggestions. I wish to thank Dr. Maurice C. Hall and Dr. Wendell H. Krull for the loan of specimens, and Dr. Frank C. Baker for the identification of the intermedi- ate snail hosts. Thanks are due also to Dr. W. H. Gates, Dr. R. L. Mayhew, Dr. J. I. Martin, the late Dr. Harry Morris, and Jane Tobie Bennett for material aid in the preparation of this work. Grateful acknowledgment is also due to the Louisiana State University for aid in the publica- tion of this monograph by a grant of seventy- five dollars to be applied on the cost of the printing. INTRODUCTION The knowledge of North American trematode life histories is very limited, and in many instances the life histories which have been described lack completeness. This is particularly true of the amphistomes. Cary (1909) published a life history of Diplodiscus temperatus which, as Cort (1915:24-30) pointed out, must be considered erroneous. Krull and Price (1932:1-37) determined experimentally the life history of this same form but omitted a description of the sporocyst. Beaver (1929: 13-22) found and described all of the developmental stages in the life history of Allassostoma parvum, with the exception of the sporocyst. However, Beaver did no experimental work except to infest the final host. Krull (1934:171-180) obtained eggs of Cotylophoron cotylophorum from Puerto Rico and determined experimentally the life history of this parasite, but he did not describe any of the developmental stages. Looss (1892:147-167) published the life history of Diplodiscus sub- clavatus (Syn. Amphistomum subclavatum) but he did not completely describe the miracidium nor experimentally infest the final host. He also described the miracidium of Gastrothylax gregarius (1896:170-177) ; the developmental stages of Gastrodiscus aegyptiacus (pp. 177-185) with the exception of the adult; and the developmental stages of Paramphistomum cervit (Syn. Amphistomum conicum) (pp. 185-191) with the exception of the adult. Takahashi (1928) described briefly some of the life history stages of P. cervt. There are two methods of attack in solving trematode life history problems. One is to attempt to prove specific identity between cercaria and adult by structural comparison, and the other is to find the relation- ship experimentally. Several authors have described amphistome cercariae and suggested the possible relationship existing between them and known species of adults, but thus far no one has conclusively demonstrated such a relationship. In the present work the experimental method was used and all of the developmental stages were studied successively. Eggs se- cured from adult worms were hatched and the intermediate snail host was determined by exposing many species of snails to the free-swimming miracidia. The life history stages consisting of the egg and its develop- ment, the mature free-living miracidium, the infestation of the inter- mediate host, the sporocyst, the redia, the cercaria, the metacercaria, the infestation of the final host, and the development of the parasite to sexual maturity in the final host are discussed. An attempt is made to evaluate the diagnostic value of certain morpho- logical features which have been considered of no specific value by recent writers in extensive revisions of the classification of the amphistomes. 7 8 ILLINOIS BIOLOGICAL MONOGRAPHS This report constitutes the first complete study of an amphistome life history and the first report of a representative of the genus Cotylophoron from the mainland of North America. MATERIALS AND-METHODS Material for the study of the various stages of the life history of Cotylophoron cotylophorum was obtained from the two kinds of host of this parasite. Mature worms were collected from the rumen and imma- ture ones from the duodenum and rumen of cows, Bos taurus, slaughtered at the city abattoir at Baton Rouge, Louisiana. The intermediate snail hosts, Fossaria parva and F. modicella, were collected from lakes, ponds, and drainage ditches in the vicinity of Baton Rouge. I-ggs deposited by worms after removal from the final host were studied alive only. Miracidia, sporocysts, rediae, cercariae, immature and mature worms were studied while alive, in toto mounts, and from sec- tioned material. Miracidia were studied alive unstained or stained intra vitam. The intra vitan stains which gave the best results were methylene blue, bril- liant cresyl violet, and neutral red. Fleming’s osmic acid, Bouin’s, or Bouin’s modified with urea and chromic acid, and sublimate-acetic solu- tion were the fixatives used but the first two were best for this material. Miracidia were stained in toto mounts with Biondi’s haematoxylin and Ehrlich’s acid haematoxylin. For sectioned material Ehrlich’s acid haema- toxylin was used most often. Sporocysts, rediae, and developing cercariae were dissected from snails for study while alive and from toto mounts. For sectioning, the entire snail was fixed in warmed Bouin’s fixative unmodified or modified with urea and chromic acid. Sublimate-acetic and modified Bouin’s were used in fixing specimens for toto mounts. The stains used most often in pre- paring toto mounts were borax carmine, alum cochineal, and Ehrlich’s acid haematoxylin. For sections the latter stain was used almost ex- clusively with alcoholic eosin as a counter stain. The mature cercariae were studied alive, in toto mounts and from sectioned material. Hot sublimate-acetic solution and Bouin’s were used as fixatives, but the fixed cercariae were always greatly contracted. Alum cochineal and borax carmine gave good results for toto mounts, and Ehrlich’s acid haematoxylin for sections. Metacercariae were studied alive only. Immature and mature worms are extremely resistant to external con- ditions and become relaxed in cold water only after several hours. The mature worms remain active from 6 to 8 hours, and the young specimens LIFE HISTORY OF COTYLOPHORON—BENNETT 9 sometimes are active after 24 hours. When relaxed the worms were placed in warmed sublimate-acetic solution or Bouin’s fixative. For toto mounts borax carmine and alum cochineal gave good results, while Ehrlich’s acid haematoxylin, Delafield’s haematoxylin, and Mallory’s triple connective tissue stain followed by eosin gave excellent results in staining sectioned worms. The final host, Bos taurus, was infested by feeding metacercariae encysted on lettuce. The rate of development and the location of the para- sites in the body were determined by killing and examining the hosts. HISTORY OF THE GENUS COTYLOPHORON Cotylophoron cotylophorum (Vischoeder, 1901) Stiles and Goldberger, 1910 was described by Fischoeder (1901:370) as Paramphistomum coty- lophorum. His brief description is as follows: Nur 5-8 mm lang, gedrungen, dorsoventral schwach abgeflacht. Ocsophagus stark musculos. Scharf abgegrenzter Genitalnapf. Hoden fast neben einander. He places this species in the family Paramphistomidae Fischoeder, 1901 and in the subfamily Paramphistominae Fischoeder, 1901. Later (1903: 546-550) he redescribes this species in much greater detail. Stiles and Goldberger (1901:15) raised the family Paramphistomidae to the rank of superfamily Paramphistomoidea, having practically the same characteristics as Paramphistomidae Fischoeder. The superfamily they divide into three families, the Gastrodiscidae Stiles and Goldberger, 1910, the Gastrothylacidae Stiles and Goldberger, 1910, and the Param- phistomidae. Paramphistomum cotylo phorum Fischoeder, 1901 was desig- nated by Stiles and Goldberger (1910:63) as the type species of their new genus Cotylophoron. They distinguish the genus Cotylophoron from Paramphistomum by a single character, the presence of a genital sucker. Fukui (1929:309) in his work on Japanese Amphistomata considers this difference not important enough to be of generic value and wishes to preserve Cotylophoron as a subgenus of Paramphistomum. I agree with Fukui and believe that Cotylophoron should be preserved as a subgenus only. On the other hand, Maplestone (1923:151) and Stunkard (1925: 141) consider Cotylophoron as a distinct genus. Stiles and Goldberger (1910:63) described a second species for the genus Cotylophoron which they designated as C. indicum. The similarity of C. indicum and C. cotylophorum is evident from the summation of the differences between the two forms by these writers. Their statement is as follows: Cotylophoron indicum comes close to C. cotylophorum, from which it differs chiefly in the structure of the oesophagus, which is provided with a bulbus thicken- eurisino7yT ‘asnoy uojeg ILLINOIS BIOLOGICAL MONOGRAPHS Of6I youusg udUIN yy ele 8 ale.ene ce w. ee (daays) SatdD iY@) OF6] YouUT eueisino7y ‘asnoy uozyeg uduNn yy umusponq jt" Pe aaa er, ** *(MOO OT}saWIOp) suinDy] sog Z6L [Ina oony oVeng 2 Sse eer Ure SOC re ene UB Oa cae DOD am an ctis 2 Of6T XNOY IT eoLyy ‘pueln[nz 9urjso]U] umusponqg Tet en ccc (aeo,, Of6l xnoyy aT POY ‘purynnz d ose oe eee ea. ehre) er tai19)lie.Sehe. 674) fel ce! ‘eh i6:-0'te) (8 oveyng UPILFY,, OF6] XNOY aT RBIIy ‘y100dajs1apugd uduIN yy ummuspond aursoquT [tiie ete tt eett erect teen ee “+ amen, O£6] XNOY aT eILY ‘j100da}s1apugd oul}so}U] uinuaponcd udUIN yy Cm Ce Me ae er eet Yar Wa a ar ie eee Sr Sen en ie ee SO ar St} Ce ec Sk Ret aet SC Se I eT (,,dee0qs,, Of61 xnoy aT uoo08uey udtUuN yy oe Bete: tavie) ~-chaidead ar etare 2.86x0.99 AVCV EGER elite sess oe Ree. ony 2.32)x.0. 71 2.41x 0.84 The faeces of both calves were examined at 2-day intervals after the twenty-first day of infestation. However, no eggs were found. Both animals were killed on January 4, 1934, aiter 46 days of infestation, in an attempt to establish the time of migration of the parasites. No parasites were found in Calf II, but 6 small mature specimens of C. cotylophorum were obtained from the rumen of Calf I. None was present in the duodenum. The parasites recovered varied in length from 3.25 to 3.85 mm and in width from 1.71 to 2.45 mm (Table 15). Only a few eggs were present in the uterus and only a few were deposited by the worms, although they were kept alive in physiological salt solution for 4 hours. The presence of mature specimens in Calf I indicates that maturity is reached in less than 46 days, or that the worms were present as a result of natural infestation before the calf was confined and were depositing so few eggs that they were missed in the faecal examinations. The latter supposition is doubtless correct in view of the fact that Krull 82 ILLINOIS BIOLOGICAL MONOGRAPHS (1934:177) determined in a series of experiments that this parasite becomes mature in approximately three and one-half months. Unfor- tunately, Krull did not determine the size at which this species becomes mature nor does he give the size of the worms recovered from the rumen of one of his experimental animals. However, Krull kindly loaned me one toto mount and one specimen serially sectioned, and a comparison of the present material to his is possible. Krull’s specimens were approximately 6 months and 20 days old and the present material was 6 months and 7 days old, if we assume that Calf I became infested a short time before being confined. A comparison of size of the oral sucker, the esophageal thickening, the acetabulum, the testes, ovary, Mehlis’ gland, and the TABLE 16.—SHOWING NUMBER, SIZE (IN MILLIMETERS), AND DISTRIBUTION OF Cotylophoron cotylophorum IN THE DUODENUM OF EXPERIMENTAL CaLF III Ne 1st foot 2nd foot 3rd foot Ath foot 5th foot 6th foot , (54 present)|(40 present)|(34 present)|(14 present)| (6 present) |(12 present) i ke eee 1.22x0.72 | 0.99 x 0.36 | 1.35x 1.05 | 2.08x0.78 | 1.61x0.39 | 1.56x 0.80 Die Bae 1.50x 0.95 | 1.43x0.85 | 1.43x0.75 | 2.26x 0.99 | 1.90x 1.06 | 1.97 x 1.06 S| ena ae 1.69x 0.93 | 1.45x 1.05 | 1.43x0.85 | 2.39x 0.80 | 2.50x0.93 | 2.26x0.85 At Shans 1.60 x 0.80 | 1.69x 0.96 | 1.71x 1.04 | 2.60x 0.78 | 2.54x 1.04 | 2.54x0.91 Se eae 1:90'x 0,95. 1,85x 1,10.) 2.13% 1:04 |-2:67 x ROL | 275 x DOL) 2 oUF ORS ete 2.00x 0.85 | 2.13x 1.04 | 2.30x 1.15 | 2.73 x 0.93 | 3.09x 1.04 | 2.75 x 0.96 ee 2:00'x 1.05°| 2.25% 05751-2550 x1.25 | 25/5 x 1,01 | 2k 2.75 x 1.01 toe reset 2.05x 1.10 | 2.25x0.80 | 2.70x1.05 | 2.76x1.04| ........ 2.149 x%41.14 OAR cer 215:X.1.05) | 22550195 2575 x1 U5" 12?8050 1806) | eee 2.99 x 1.04 LO ass 3105.x0:95 |2,60ise1510) 12580105: | 2.99101) fio ee 3.09 x 1.04 Average..| 1.94x 0.94 | 1.95 x 0.90 } 2.11x 0.96 | 2.61x 0.94 | 2.23x 0.90 | 2.63 x 0.99 genital sucker of Krull’s sectioned material and similar structures in the smallest of the worms from Calf I demonstrates that the specimens are approximately the same age. The finding of no immature specimens in either the rumen or the duodenum indicates that none of the metacercariae fed to the calf developed. This experiment was repeated in another attempt to determine the time of migration of parasites from the duodenum to the rumen. Two 4 months old calves which had not had access to infestation were obtained and kept under conditions similar to those of the first experiment. Calf III was fed 300 metacercariae on June 4, 1934, 300 on June 11, and 300 on June 18, making a total of 900 fed at 7-day intervals. Calf IV was fed a total of 1200 metacercariae at 7-day intervals from June 4 to June 25. Calf III was examined on June 25, 1934, 21 days after the first infestation, and 203 immature specimens of C. cotylophorum were recovered. Of these, 199 were distributed in the anterior 6 feet of the LIFE HISTORY OF :COTYLOPHORON—BENNETT 83 duodenum and 4 were found in the rumen. The other parts of the stomach were examined but no parasites were found. The smallest specimen from the duodenum measured 0.99 by 0.36 mm and the largest was 3.09 by 1.04 mm. There was no distinct grouping according to size so that it was impossible to determine the exact age of any one specimen. However, it may be safely assumed that the smallest worms were only 7 days old, whereas the largest were 21 days old. The large and small individuals were distributed irregularly in the duodenum so that it was again impossible to group them according to their distribution (Table 16). However, the largest number of small specimens was found in the upper 3 feet. of the duodenum, indicating that the metacercariae probably excyst in this region. Most of the worms distributed posteriorly were much TABLE 17.—SHOWING NUMBER, SIZE (IN MILLIMETERS), AND DISTRIBUTION OF Cotylophoron cotylophorum IN THE DUODENUM OF EXPERIMENTAL CALF IV No. 1st foot 2nd foot 3rd foot 4th foot 5th foot (eee Re are 2.13x1.04 | 1.71x0.78 | 2.21x0.88 | 1.69x0.83 | 2.41x0.80 DAG et Grates cos Deen 2.31x0.96 | 2.08x0.78 | 2.34x0.88 | 2.36x0.91 | .......... SR eae De sac OrOle|e22 62x. 0872. | 234 OC9L Wn uw tes ae. || ceca sete oe AR te eet hs DESO 1 O4 oer ereae. D3 OxO Soy ll ko cee a sesssevn Clk seseeosee wiace Se rere eerie. toe. Ilan siSeaeh DEAT OL OGR Serre ets ener ee Oe ers ns aN oe eS asdsaletes DESO OP 96ell Soak. ohare Al oars eee tr pee erent Se No oom hyo oe | aretha alte ys De SACO Sele es ee aeons tia tsere okt CP ee ie lata etry || od gh Straten 2360 6.092 |b githc huss tote. We fees a oe ORE siecle bl) Agliaaeenses DRT SOOO eects ildeeis eae: Average...... 2.28x0.99 | 1.60x0.76 | 2.44x0.91 | 0.02x0.87 | 2.41x0.80 larger than the smallest worms, indicating that the worms either migrate after becoming excysted anteriorly or that some metacercariae are carried farther before being liberated. The average size of the 199 specimens was 2.28 by 0.94 mm. The 4 specimens found in the rumen of this host indicate that migra- tion begins at the end of the first 3 weeks after infestation. These specimens varied from 2.06 to 2.95 mm in length and from 0.63 to 0.84 mm in width (Table 15). The average size of the 4 was 2.32 by 0.71 mm. Calf IV was examined on July 25, 1934, 51 days after the first infestation and 30 days after the last infestation. Nineteen specimens were recovered from the first 5 feet of the duodenum, 34 from the rumen, and 1 from the pylorus (Table 17). Those from the duodenum were much more uniform in size than those from the duodenum of Calf III (Table 16). The smallest specimen measured 1.95 by 0.78 mm and the largest 2.86 by 0.99 mm. The average size of the 19 from the duodenum was 2.32 by 0.75 mm, while the average size of the 34 from 84 ILLINOIS BIOLOGICAL MONOGRAPHS the rumen was 2.33 by 0.83 mm. The one specimen from the pylorus measured 2.43 by 0.81 mm. The small number of parasites present in this host and their uni- formity in size indicates that probably only one group of metacercariae TABLE 18—DatTA ON SIzE (IN MILLIMETERS) OF Cotylophoron cotylophorum IN TRE DUODENUM AND RUMEN OF NATURALLY INFESTED Hosts Age of host: 2 Age of host: 6 months Age of host: 6 months years (none pres- (16 present in duodenum) | (7 present in duodenum) | ent in duodenum) a: (7 present in rumen) (39 present in rumen) (128 present in No. rumen) Duodenum Rumen Duodenum Rumen Rumen (7 smallest) (20 smallest) Neca arte 1.04x0.41 | 2.54x1.17 | 0.96x0.83 | 2.44x1.19 1.°82'x'1,:22 oD puss asthe 1.22x0.52 | 2.62x1.30 | 1.35x0.78 | 2.60x 1.30 1.87x 1.08 Sieh 1.97x0.80 | 2.63x1.04 | 1.43x0.85 | 2.62x 1.56 1.92x 1.04 Aide apt eae 2.00x0.91 | 2.70x0.98 | 1.56x0.91 | 2.71x1.56 1.92x1.17 Sch soe 2.10x0.96 | 2.99x 1.22 | 1.87x1.06 | 2.83x1.53 2.00 x 1.06 ORM gic: 2.15x0.85 | 3.12x1.30 | 2.08x 0.98 | 3.12 1.45 2.00x 1.17 Nex Roraa 2.21x0.65 | 3.30x1.01 | 2.39x0.78 | 3.12 x1.58 2.02x1.17 Oia D2 SX OLS uly va eo te tee, een ate Me oe 2.05x1.17 Oren ae DAZ Orxa OYA Oia Ws hee teeny | en ae rere rere || pays Aen 2.08 x 1.04 Oe Mee eyes 2520 Sa0 Gln) Casa heck at ee ee ee erenea nae 2.08x 1.09 1 eee se DDO: S80 BhSs | Bs uses. ee ee | oe ce een | ee nee ee 2.08x 1.11 A ee De SAO 18h Mee) ae eek | eet Sere: Gee eee 2.08x 1.17 13 race DIS OXI" OSG Tie. 4s Seco een | eee ae eee | ioe eer ee 2.08x 1.17 1 eae DPS 2 XAOS Bia ce ecco eae Meek eerie cet || coe 2 AS x71 WSR acts 2EO2 50 ORO SM ime serves on mee rtetpty ee mei | eevee epee De 2 lexelet Glee sere Pei Oo e{ 0 Fao Kea gamers Ao | ae AG, PaeOar Poe gee 0d 2h 2.21x 1.30 Lak Seah oh aeavirah oe: bie a. oe) Rie rice, eal Mee eae ne eee FIP nas eer oe 2.26x 1.06 US eee saves tsvel| py as ees e og te Se al Se | DOS, Sueseeeateer em ap rere 2.34x1.17 LO ree eats cclll Marlatt qe ettarsionesa||4 goed care ees rn | sg eee ae Ome | ete en ee Qe] XA 22 DO on camnal we 8 chet: Galas dean! Vete Sate ASG | dan eee 2°52:x,1. 30 Average} 2.15x0.72 | 2.86x1.15 | 1.66x0.88 | 2.78x 1.45 2.10x1.14 fed to the calf produced the infestation. The average size of worms from the duodenum of Calf IV is only slightly greater than that of the worms from the duodenum of Calf III, which seems to indicate that it was the last feeding of metacercariae to Calf IV which produced the infestation. A comparison of the average size of the parasites from the duodenum and the rumen of Calf IV clearly indicates that the worms were migrating and that very little growth occurs during their passage through the other parts of the stomach. That this passage is rapid is indicated by the fact that only one specimen was found in other parts of the stomach. The variability of the size of the worms in the rumen com- bined with the fact that there is a decided overlapping of size with those in the duodenum indicates that the worms migrate singly and that the LIFE HISTORY OF COTYLOPHORON—BENNETT 85 migratory period for any group of worms of the same age may extend over several days. Thus in Calf III, only 4 of 203 worms had migrated at the end of 21 days, and in Calf IV, 34 of 54 had migrated at the end of 30 days. The size at which the worms migrated from the duodenum to the rumen in the experimental animals can be correlated with findings in naturally infested hosts. Many naturally infested animals were examined which contained the parasites in both the duodenum and the rumen. Others were examined in which only the duodenum or rumen was infested. Three such cases are presented in Table 18. The host repre- sented in the first column was infested by 128 specimens in the rumen, 15 of which were mature. The average size of 20 of the smallest speci- mens is 2.1 by 1.14 mm. These worms are slightly shorter but wider than those from the rumen of experimental animals. The parasites shown in column 2 of Table 18 were collected from the duodenum and rumen of a 6 months old calf. Sixteen were found in the duodenum which had an average size of 2.15 by 0.79 mm. Only 7 were found in the rumen. These averaged 2.86 by 1.15 mm. The parasites shown in column 3 were collected from another 6 months old calf. In the duodenum of this calf there were 7 parasites which averaged 1.66 by 0.88 mm. There were 39 specimens in the rumen, the largest of which measured 5.33 by 1.82 mm. The average size of 7 of the smallest specimens was 2.78 by 1.45 mm. In these three cases there is further evidence that the worms migrate from the duodenum into the rumen of the final host when considerably less than 3 mm in length. A graph made using the data on specimens from both experimentally and naturally infested animals demonstrates that the greater number of worms migrate at a size of 2.37 by 0.98 mm. From the above data it is possible to conclude that the metacercariae become excysted in the duodenum where they develop for 3 to 5 weeks. Following this period they migrate to the rumen’ at an average size of 2.37 to 0.98 mm. DEVELOPMENT The metacercariae excyst in the upper part of the duodenum but some may be carried as far posterior as 6 feet, as has been previously pointed out. The distribution of the various sizes found in the duodenum of experimental hosts indicates that some migration may occur within the limits in which they were found. The young forms are very active and migration for considerable distances is probably a matter of a very short time. In the duodenum they are found attached to the mucosa by a power- 86 ILLINOIS BIOLOGICAL MONOGRAPHS fully developed acetabulum, elongating and weaving their bodies from side to side. The worms are capable of moving rapidly from one position to another in the measuring worm manner. The color of the worm is reddish, which makes it very inconspicuous against the background of mucosa. To collect the worms, sections of the duodenum were placed in warm physiological salt solution. This increases their activity which makes them more easily seen. They were then scraped off and shaken free of all tissue from the duodenum. The shape of the young worm is very much like that of the adult, being attenuated at the anterior end and widest in the testicular region. The dorsal surface is convex and the ventral surface is slightly concave. In cross section the body is nearly ovoid or round. The acetabulum is subterminal in living specimens, but when allowed to die unfixed the acetabulum opens posteriorly and the body becomes much flatter. The young worms are more active than the adults and are able to extend the body three times their contracted length while the adults are not capable of extending the body more than one and a half times their contracted length. Young individuals are also much more resistant than the adults. Some of the young specimens from the duodenum remain alive for 24 hours in cold physiological salt solution while older worms remain alive only 6 to 8 hours under similar conditions. The age and size at which these parasites become mature was not determined experimentally, but by examining naturally infested animals a series of developmental stages varying from 1 to 11 mm in length was obtained. The smallest mature specimens measure 2.86 by 1.22 mm. Many are mature at a length of 3 mm. Krull (1934) has shown that these worms reach maturity in approximately three and one-half months, and the correctness of his findings has been pointed out previously (page 82). Since the worms migrate at an average size of 2.37 by 0.98 mm during the fourth and fifth weeks after infestation of the host and mature at the sizes given above it is evident that the rate of growth in the rumen is slow. This is shown also by the average size of the worms from the rumen of Calf I. Those worms which were 6 or 7 months old averaged only 3.55 by 2.32 mm. The results obtained from the examination of a bull brought in to the animal pathology department of Louisiana State University are also of value in demonstrating the slow growth rate of these forms. This bull was brought in for observation on August 10, 1933, and was kept, as were the experimental calves, with no chance of becoming infested with C. cotylophorum. Upon examination on June 12, 1934, 26 specimens of C. cotylophorum were found in the rumen. The smallest of these worms measured 5.2 by 2.1 mm and the largest 7.0 by 2.75 mm. The average LIFE HISTORY OF COTYLOPHORON—BENNETT 87 size of the 26 was 5.6 by 2.34 mm. This bull had been confined slightly more than 10 months so that the smallest of the specimens must neces- sarily have been somewhat over 10 months of age. The largest specimens found from other naturally infested hosts never exceeded 11 by 3 mm. Specimens of this size were probably well over one year in age and represent the maximum size attained by the parasites in this host. No information other than the above was obtained concerning the longevity of these forms. The adult of this species has been fully described by Fischoeder (1901, 1903), Stiles and Goldberger (1910), Maplestone (1923), Bennett (1928), and Stunkard (1929) so that no detailed descriptions of struc- tures will be given here. Descriptions of the development of structures of diagnostic importance and of structures which have not been described for this parasite are included. Digestive Tract.—In the smallest individuals the digestive tract is identical in appearance to that of the largest worms. The caeca are in the same position in both, that is, in the dorso-lateral part of the body and terminate dorsal to the acetabulum. The posterior ends may be curved ventrally anterior to the acetabulum, but such variations are of no importance as pointed out by Maplestone (1923) and can be explained on the basis of differences in the degree of contraction. The oral sucker changes consist of an increase in size only. Its growth, however, is not proportionate to that of the body. Its length in 1 mm worms as compared with the body length is in the ratio of about [25 ine toroenim worms the ratio is 126 or 1:7“ and in 4 to 5 mm worms the ratio is 1:6. The oral sucker attains its maximum size in worms of 6 to 7 mm and the ratio is about 1:9. In a well extended specimen measuring 6 by 2.5 mm the oral sucker is 0.74 mm long, 0.58 mm wide and 0.46 mm dorso-ventrally. The worms may reach a size of 11 by 3 mm but there is no further increase in the size of the sucker. The esophagus is the only structure of the digestive tract which possesses characteristics of specific importance. These are its length and the gradual increase in thickness of its walls from its anterior to its posterior end. The length of the esophagus is subject to considerable variation because of contraction but it increases in length as the worms develop, reaching its maximum length in worms of 6 to 7 mm in length as does the oral sucker. In the smallest worms obtained the esophagus is about 0.3 mm long and it increases steadily as the worms grow, but it never exceeds 0.9 mm in length. It bifurcates to form the intestinal caeca in the region of the genital pore in worms under 7 mm long (Figs. 81, 82, 83). However, the worms reach 11 mm in length and as a re- sult the genital pore becomes distinctly post-bifurcal in position. 88 ILLINOIS BIOLOGICAL MONOGRAPHS Stiles and Goldberger (1910:72) state that the genital pore of C. indicum is decidedly post-bifurcal and designate this as one of the differences between C. indicum and C. cotylophorum. Maplestone (1923:152) has pointed out that this characteristic is too variable to be of diagnostic importance for these two species, and the present findings support his contention. The muscular thickening of the esophagus in C. cotylophorum is evident in the cercaria and becomes more evident as the worm develops in the final host. In the small worms the muscle wall at the proximal end of the esophagus is about 5 » thick and at its distal end is 15 p thick, while the diameter of the esophagus at the proximal end includ- ing the esophageal glands is 37 » and at the distal end is 85 p. The ratio of these measurements is found to vary from 1:2 in young worms to 1:4 in old worms. The thickness of the muscle wall at the proximal end does not exceed 20 p, and it does not exceed 60 p at the distal end. In the largest of the worms the total diameter of the proximal end does not exceed 0.17 mm and does not exceed 0.32 at the distal end. All of these measurements are subject to considerable variation but there is a normal increase in the size of the esophagus concurrent with growth. However, growth of the esophagus stops when the worms reach a size of 6 or 7 mm. The difference in the thickness of walls of the esophagus at the two ends is very evident at all ages (Figs. 70-73), and the appearance of this structure is very similar to that in C. cotylophorum as described by Fischoeder (1903:547) and Maplestone (1923-152). Maplestone (p. 152) attempts to show that the esophagus of C. indicum and C. cotylophorum are identical, but I cannot agree with him. As stated, the esophageal thickening in the present material is very evident at all ages and sizes of worms. Stiles’ and Goldberger’s ma- terial possessed no such thickening, although their figure (1910:fig. 45, p. 66) shows that the walls of the esophagus are thick. The apparent muscular thickening shown in their figure is due to an increase in the lumen rather than to an increase of thickness of the walls. I have been able to determine this point from a sectioned specimen of a worm identi- fied as C. indicum by these writers. The thickness of the walls of the esophagus in this material does not exceed 10 p at its proximal end and does not exceed 20 p at its distal end. The diameters of the two ends are 0.105 and 0.195 mm respectively. The above worm, which was not mature, measured 5.16 by 1.68 mm. These differences are too great to be the result of normal variation, as determined by a comparison with the present material. Development of Sex Organs.—The primordia of the genital organs PIPE FISTORY OF “COTY LOPHORON—BENNETT 89 are present in the cercaria, as previously described. In the smallest worms recovered from the final host the ovary, Mehlis’ gland, and testes were differentiated (Fig. 77). The ovary and Mehlis’ gland are repre- sented by two small masses of cells located near the center of the body above the anterior margin of the acetabulum. From Mehlis’ gland a cord of cells, in which there is no lumen, passes ventrally over the anterior margin of the acetabulum to the ventral region of the body. It turns forward and continues anteriorly near the ventral surface to reach a mass of cells located above the position of the future genital pore. The testes are located laterally, one on each side of the cord immediately anterior to the acetabulum. Their method of formation was not de- termined, but their position suggests that they are set off from the ventral side of the mass of cells located anterior and dorsal to the aceta- bulum in the cercaria. The ovary and Mehlis’ gland doubtless are formed from the dorsal part of this mass. There is no indication of a lumen in the cord of cells at any place. The testes are surrounded by a thin membrane but no vasa efferentia were observed. The genital pore is not yet formed, and the only indication of a genital sucker is a slight thickening of the body wall and a mass of deeply-staining cells which are probably cells of the prostate gland. The degree of development described above is reached in worms of approximately 1.0 by 0.65 mm. In individuals of this size the ovary measures 0.045 by 0.03 mm, Mehlis’ gland 0.037 by 0.022 mm, the testes 0.065 by 0.045 mm, the diameter of the cord of cells 0.045 mm, and the mass of cells surrounding the genital pore 0.097 by 0.032 mm. The vasa efferentia, the vas deferens, the uterus, and a genital pore were clearly distinguished in an individual 1.17 by 0.8 mm. The uterus follows a course from Mebhlis’ gland to the ventral side of the body similar to that of the cord of cells described in the above form and is doubtless formed from it. Here it turns dorsally and anteriorly until it reaches the center of the body. It passes forward for a short distance and then turns ventrally. Near the ventral surface it turns forward to the genital pore. It joins the vas deferens, and the common duct thus formed, the ductus hermaphroditicus, opens to the outside (Fig. 63). In this same specimen the testes have taken the tandem arrangement characteristic of the mature worm. The vasa efferentia are conspicuous and are easily traced. The one from the posterior testis passes anteriorly and dorsally until it reaches the mesial side of the right caecum where it turns forward. The vas efferens from the anterior testis passes forward mesial to the left caecum. The two unite in the center of the body a short distance posterior to the genital pore and immediately anterior to the descending uterus. The vas deferens thus formed coils ventrally and 90 ILLINOIS BIOLOGICAL MONOGRAPHS anteriorly to the genital pore. It is located dorsal to the uterus and unites with it to form the ductus hermaphroditicus. The position of the vasa efferentia and vas deferens indicates that these structures are formed from the dorsal part of the cord of cells described in the smaller individuals. The ventral position of the uterus near the genital pore indicates that it is derived from the ventral part of the cord. The descent of the uterus posterior to the loop formed by the union of the vasa efferentia supports this conclusion also. The genital sucker becomes more evident in specimens of this size, although as yet there are no definitely differentiated muscles in it. It consists of a compact mass of cells surrounding the terminations of the vas deferens, the uterus, and the ductus hermaphroditicus. This mass of cells is approximately 0.12 mm long, 0.108 mm wide, and 0.072 mm thick (Fig. 63). All of the male and female genital structures, with the exception of the vitellaria, are formed before the worms migrate from the duo- denum to the rumen. Following the stage just described the other structures character- istic of the genitalia of the mature worm are rapidly developed, being present in worms 2.5 mm long and less than 3 weeks old (Fig. 76). The vas deferens is differentiated into several distinct regions: a seminal vesicle, a pars musculosa, the prostate gland, and the ductus ejacula- torius, which joins the ductus hermaphroditicus. The ductus hermaphro- diticus passes through the center of a minute hermaphroditic papilla which opens into a small genital atrium in the genital papilla. The copulatory structures and the terminations of the male and female ducts are enclosed in the genital sucker. Laurer’s canal is well developed in individuals of this size also. It passes from the oviduct dorsally and laterally to open to the exterior behind the excretory pore and to the left of the median line. The only other development in the female system is the formation of the metraterm. There is no recognizable change in the worms immediately follow- ing their migration into the rumen, which is a second indication that the time required for migration is very short. The fact that only one worm was found in other parts of the stomach other than the rumen has been considered above as an indication that the worms migrate from the duodenum to the rumen rather quickly. No worms of known age were studied from the time of migration but many specimens representing all sizes and stages of development were secured from naturally infested hosts. There is very little increase in size before the worms reach sexual maturity and this increase is in LIFE HISTORY OF COTYLOPHORON—BENNETT 91 diameter. Thé smallest mature worm collected measured 2.86 by 1.43 mm. The most conspicuous changes in the small mature worms as com- pared to the immature ones are the increase in size of the genital organs and the development of the vitellaria (cf. Figs. 76 and 79). In the smallest of the mature worms the vitellaria are very sparsely developed in the lateral regions of the body and extend from the esophagus to the acetabulum. The testes in immature worms at the time of migration are round and smooth and measure only 0.1 mm in diameter. In the smallest of the mature worms the testes are 0.36 by 0.26 mm; they extend dorso- ventrally for a distance of 0.48 mm and are distinctly lobed. There is an increase in the size of the ovary from 0.075 mm to 0.196 mm in diameter. The uterus in both the immature and small mature worms is straight but its diameter increases from 0.032 mm in the immature to 0.081 mm in the mature worms. The vasa efferentia remain unchanged but the vas deferens becomes greatly coiled. The genital sucker and copulatory structures are also much more conspicuous in the small mature worms. The genital sucker in worms which have just migrated to the rumen measures 0.17 mm in diameter and the muscle mass is about 0.14 mm thick (Fig. 76). In small mature worms this structure measures 0.4 mm in diameter and is 0.22 mm thick. The only marked change which occurs after sexual maturity is attained is the rapid development of the vitellaria. In worms only 3.5 mm in length they have reached a state of development comparable to that in the largest worms (Fig. 80). They extend in closely grouped follicular masses from the oral sucker to the acetabulum, principally in the extra-caecal zones but approach the median line both dorsally and ventrally. The uterus becomes more coiled as larger numbers of eggs are produced and fills all available space between the acetabulum and the posterior testis. It is coiled transversely dorsal to the testes, and more coils are formed in the ventral region of the body anterior to the anterior testis. Stunkard (1929:244) found that C. cotylophorum reached maturity at a much smaller size in calves than in antelopes, but he could not ex- plain the incongruity. He did not give the size of the mature worms from the calves but specimens as long as 6 mm from the antelopes were not mature. These findings clearly indicate that these parasites mature at a much smaller size in some hosts than in others. The genital organs are much larger in fully grown worms than in those just reaching maturity (cf. Figs. 79 and 81). The testes are located in tandem arrangement near the center of the body and occupy approximately two-fifths of the body length. The seminal vesicle is 92 ILLINOIS BIOLOGICAL MONOGRAPHS greatly expanded and coiled; the pars musculosa is thick, muscular- walled, and coiled; the pars prostatica located directly above the genital pore is straight and measures about 0.20 by 0.22 mm. Its lumen is large but narrows abruptly as it becomes continuous with the ductus ejacula- torius. The ductus ejaculatorius is about 0.19 mm long and opens into the ductus hermaphroditicus. The hermaphroditic papilla varies in length with its state of contraction but its length is about 0.1 mm. The genital papilla encloses a small atrium into which the protrusible hermaphro- ditic papilla projects. The walls of the genital papilla are very muscular and are about 50 p thick. The genital papilla when protruded measures about 0.19 by 0.14 mm and projects into the cavity of the genital sucker (Fig. 74). The ovary and Mehlis’ gland in fully grown worms are located above the anterior margin of the acetabulum. The uterus is crowded with eggs and is coiled anterior to the acetabulum, dorsal to the testes, and in the ventral region of the body anterior to the anterior testis. The mus- cular metraterm joins the ductus hermaphroditicus. The union of the male and female ducts forms a distinct but small vesicle at the inner end of the ductus hermaphroditicus. The genital sucker consists of a muscular mass which encloses the terminal ends of the male ducts and the copulatory apparatus. This structure increases in size as the worms develop but does not exceed 0.7 mm in diameter in any of the present material. Its walls are approxi- mately 0.3 mm thick. The cavity of the sucker is considered as a genital atrium by Fischoeder (1903) and Maplestone (1923). The genital pore is the opening of the sucker while the pore of the ductus hermaphro- diticus is the porus hermaphroditicus. When the worms are emitting eggs or sperm the genital papilla can be protruded for a short distance beyond the edge of the genital sucker. At the same time rapid contractions and relaxations of the muscles of the genital sucker occur. The genital atrium, the genital papilla, and the genital sucker are subject to considerable change in shape and size. The hermaphroditic papilla is also subject to great changes in size and appearance. However, in the present material after their development was completed these structures were evident in all ages and sizes of worms, and in all states of contraction (Figs. 68, 69, 74, 75). Maplestone (1923:153-155, figs. 8, 9) describes in detail the extreme variability in the appearance of the genital sucker and copulatory apparatus of C. cotylophorum and concludes that these structures are of no diagnostic value. His figures (Figs. 8, Al, A2, B) represent the appearance of the genital sucker and copulatory apparatus of C. TIFE HISTORY OF COTYLOPHORON—BENNETT 93 cotylophorum as described by Fischoeder (1903:548, fig. 38) and of C. indicum as described by Stiles and Goldberger (1910:69, fig. 48). As a result of his observations on these structures and on the variability of the esophagus of C. cotylophorum he considers C. indicum as a synonym of C. cotylophorum. Fukui (1929:319) agrees with Maplestone and designates C. indicum as a synonym of C. cotylophorum. As originally described by Fischoeder the genital sucker of C. cotyl- ophorum is much larger and much more distinctly set off from the body parenchyma than in Maplestone’s or the present material (Fig. 67). Fischoeder does not describe a genital papilla in C. cotylophorum and the male and female ducts remain separate in the hermaphroditic papilla. The genital sucker of C. indicum as described by Stiles and Gold- berger is also distinctly set off from the body parenchyma and they do not describe a genital papilla as being present. In the present study some of the original material of Stiles and Goldberger was studied and no genital papilla was found. There is also a distinct difference in the ap- pearance of the genital sucker of C. indicum and that of C. cotylophorum as described and figured by Maplestone (1923:156, fig. 9) and as de- scribed in this paper. Stunkard (1923:138) believes that Maplestone’s conclusions as to the importance of these structures are erroneous. I am of the same opinion, and in view of the decided differences in the appearance of the genital sucker, the copulatory apparatus, and esophagus of C. indicum as compared to C. cotylophorum | cannot consider these two species as synonymous. The present specimens of C. cotylophorum agree in every detail with Maplestone’s description of this species with the exception of the ex- treme variability of the copulatory apparatus as pointed out above, with Stunkard’s description (1929:244-251), and with specimens loaned me by Krull. However, | believe that the differences between the genital sucker and copulatory apparatus of Fischoeder’s material and the present material are of diagnostic importance. Since these differences are the only ones which have been observed | am hesitant in considering these differences as being of specific value in view of Maplestone’s and Fukui’s findings. Excretory System.—The arrangement of the excretory system in the young and mature specimens is very similar to that of the cercaria (Fig. 60). The details of the system were not studied. Only living immature specimens under pressure were studied. It was possible in this way to determine the course and extent of the larger ducts and the position of the bladder. 94 ILLINOIS BIOLOGICAL MONOGRAPHS The bladder is an elongate structure located dorsally in the posterior region of the body, extending from near the posterior margin of the acetabulum to slightly past the anterior margin. It opens to the exterior through a narrow short muscular duct lined with cuticula continuous with that of the body surface. It may pass directly to the surface from the middle or anterior end of the bladder or may extend forward from it (Figs. 77, 78). In young specimens the former condition is more often found, and it is only in the more fully developed and very ex- tended individuals that the duct opens very far in front of the bladder. The pore is located in the medial dorsal line, usually directly above the posterior margin of the posterior testis in mature specimens, but it may be as far forward as the middle of the anterior testis, or as far posterior as the anterior margin of the acetabulum. Its position relative to these organs depends entirely on the age of the individual and its state of con- traction. However, the position of the pore may be considered as pre- vesicular, being dorsal to the bladder only in immature or contracted mature specimens. Maplestone (1923:157, text-fig. 11) has described and shown similar conditions in specimens of C. cotylophorum of different ages. I did not observe the pore to be post-vesicular in any of my material as Maplestone has figured it in a very young specimen. Fukui (1929:275) has described similar variations in Paramphistomum explanatum, P. cervi, and P. orthocoelium. He states that the pore is very variable in position and cannot be used for exact diagnostic purpose, but that it is roughly definite for species. The main excretory canals are located the same as in the cercaria. From their union with the posterio-lateral angle of the bladder on each side they pass outward and forward. Immediately posterior to the middle of the body length these canals bend mesially and a cross con- nection passes across the middle line and sends off a forward diver- ticulum. The main canals then curve outward and forward. The diver- ticulum present just posterior to the eye in the cercaria is present in these older worms, and in them it receives a small duct which in turn receives branches from the esophageal region. The main canals continue forward from this diverticulum until they reach the posterior margin of the oral sucker. Here they turn abuptly on themselves and pass pos- teriorly in the lateral regions of the body. These posterior extensions could not be traced to their terminations but doubtless they extend as far back as the acetabulum, as they do in the cercaria. A small duct on each side extends forward from the turning point of the main canals which drains the anterior region of the body. Numerous small ducts which are symmetrically located empty into the larger canals throughout their course. LIFE AISTORY OF COTYLOPHORON—BENNETT 95 The anterior diverticulum from the cross connection becomes greatly enlarged and it also receives small ducts from the anterior dorsal region of the body. A detailed description of the excretory system was made from pre- served material by Bennett (1928:22-23). The excretory system of this material is very similar to that of Gastrothylax and Paramphistomum as described by Fukui (1929:272). This type of system he designates as Type A and calls it H-shaped. SPECIFIC DESCRIPTION OF Cotylophoron cotylophorum The following specific description of C. cotylophorum is based en- tirely on the characteristics of the material used in the present study. Body of mature worm 3 to 11 mm long by 1.15 to 3 mm wide; conical in form, greatest width in testicular region; tapers to bluntly pointed anterior end, posterior end broadly rounded; dorsal surface convex longitudinally and transversely, ventral surface concave longitudinally, convex transversely; oval to round in cross section. Surface without spines or papillae. Genital pore bifurcal or slightly post-bifurcal, at junction of first and second body thirds, surrounded by genital sucker 0.4 to 0.7 mm in diameter which forms a distinct projection in the median ventral line. Acetabulum at posterior end, distinctly subterminal 0.75 to 1.36 mm in diameter. Mouth at blunt anterior extremity; oral sucker pyriform in sagittal section; 0.52 mm long, 0.45 mm wide and 0.39 mm in dorso-ventral diameter in small mature worms, its maximum in fully grown individuals 0.74 mm long, 0.58 mm wide and 0.45 mm in dorso-ventral diameter; esophagus slightly longer than oral sucker; its walls increase in thickness posteriorly, ratio of thickness of anterior wall to posterior wall 1.3; caeca arise from dorso-lateral aspects of end of esophagus, terminate in acetabular zone. Excretory pore in median dorsal line about at junction of median and posterior body thirds; ex- cretory bladder extends posteriorly from pore above acetabulum; lateral excretory tubes extend from ventral and postero-lateral margin of bladder to oral sucker, turn sharply posterior to acetabulum; cross connection between lateral ducts in dorsal region and near middle of body length, median diverticulum extends forward for short distance from cross connection, lateral diverticulum from each lateral duct a short distance posterior to oral sucker. Testes large, lobate, about size of oral sucker in young mature worms, larger than acetabulum in old specimens, in median line, tandem arrange- ment; union of vasa efferentia slightly anterior to anterior testis; vas deferens coiled; its vesicula seminalis coiled, expanded; pars musculosa coiled, narrow; pars prostatica straight, located directly above genital 96 ILLINOIS BIOLOGICAL MONOGRAPHS sucker ; ductus ejaculatorius short, unites with metraterm to form ductus hermaphroditicus ; hermaphroditic papilla short, protrusible, arises from the vertex of a conspicuous genital papilla, almost filling the cavity of the papilla; genital papilla in turn surrounded by the genital sucker. Ovary and Mehlis’ gland above anterior margin of acetabulum; Laurer’s canal passes over excretory bladder, opens posterior to excre- tory pore and left of median dorsal line; uterus coiled anterior to ace- tabulum, passes anteriorly dorsal to testis, descends vertically over the anterior margin of anterior testis, anteriorly again ventral to vas defer- ens, enters genital sucker; and metraterm unites with ductus ejacu- latorius. SUMMARY AND CONCLUSIONS Cotylophoron cotylophorum is a widely distributed parasite of rumi- nants but has not been previously reported from the mainland of North America. The time required for the miracidium to develop varies directly with temperature. In the present experiments eggs kept at room tempera- tures hatched in 11 to 29 days. The structures of the miracidium develop in sequence and are rec- ognizable before hatching occurs. , The miracidium is similar to other amphistome miracidia. A study of the descriptions of 18 different species of miracidia indicates that the number and arrangement of ciliated epidermal cells is of taxonomic value. The snails Fossaria parva and F. modicella are capable of serving as the intermediate hosts of C. cotylophorum. The former is the natural host of this parasite in Louisiana. The miracidium penetrates the mantle, head, and foot of the snail, loses its ciliated epidermal cells, and transforms into a sporocyst. The sporocyst develops rapidly and produces 9 rediae. The rediae are born at an average size of 0.188 by 0.056 mm and migrate into the liver and ovo-testis where their development is complete. Each redia produces approximately 25 cercariae. Mother rediae may occur in the life cycle but were observed in only one instance. Cercariae are born in an undeveloped condition and continue their development in the liver and ovo-testis. The time required for the development of the sporocyst, redia, and cercaria varies directly with temperature. Infested snails kept under natural temperature conditions shed cercariae in 30 to 91 days. LIFE HISTORY OF COTYLOPHORON—BENNETT 97 The cercariae encyst on vegetation and the metacercaria lives for over 3 months. The metacercariae become excysted in the duodenum of the final host. Migration from the duodenum to the rumen begins in 21 days at an average size of 2.37 by 0.98 mm and may continue over a period of about 14 days. The worms do not migrate at the same age or size. The worms become mature after reaching the rumen at an age of about three and a half months, at a size of approximately 3.0 by 1.15 mm. They reach their maximum size in about one year. The time required to complete the life cycle of C. cotylophorum varies from about 5 to 8 months. C. indicum is not a synonym of C. cotylophorum. 98 ILLINOIS BIOLOGICAL MONOGRAPHS BIBLIOGRAPHY AMEEL, D. J. 1934. Paragonimus, Its Life History and Distribution in North America and Its Taxonomy (Trematoda: Troglotrematidae). Amer. Jour. Hyg, 19:279-317, 6 pls. Bartow, C. H. 1925. The Life Cycle of the Human Intestinal Fluke Fasciolopsis buski (Lankester). Amer. Jour. Hyg., Monographic Series, no. 4. BEAVER, P. C. 1929. Studies on the Development of Allassostoma parvum Stunkard. Jour. Parasitol., 16:13-24, 1 pl. 1936. Experimental Studies on Echinostoma revolutum (Froelich), a Fluke from Birds and Mammals. Ill. Biol. Monog., 15: No. 1. (In press). BENNETT, H. J. 1928. A new Species of Cotylophoron from Bos taurus. Collected in Louisiana. Manuscript, University of Illinois Library, Urbana. Brooks, F. G. 1930. Studies on the Germ Cycle of Trematodes. Amer. Jour. Hyg., 12: 299-340, 7 pls., 4 text-figs., 2. Carvel wR: 1909. The Life History of Diplodiscus temperatus Stafford. Zool. Jahrb., Abt. f. Anat., 28:595-659, 4 pls. Cor, W. R. 1896. Notizen uber den Bau des Embryos von Distomum hepaticum. Zool. Jahrb., Abt. f. Anat., 9:561-571, 1 pl. Cort, W. W. 1915. Some North American Larval Trematodes. Il. Biol. Monographs, 1, no. 4:1-86, 8 pls. 1919. Notes on the Eggs and Miracidia of the Human Schistosomes. Univ. Calif. Publ. Zool., 18:509-519, 7 text-figs. 1922, A Study of the Escape of Cercariae from their Snail Hosts. Jour. Parasitol., 8:177-184, 4 tables. Dusots, G. 1928. Les Cercaires de la Région de Neuchatel. Soc. Neuchateloise des Sci. Nat., 53:1-153, 8 text-figs. Faust, E. C. 1919. Notes on Some South African Cercariae. Jour. Parasitol., 5:164-175, 1 pl. 1919a. The Excretory System of Digenea. Biol. Bull., 36:315-321, 4 text-figs. Faust, E. C., and MELeney, H. E. 1924. Studies on Schistosomiasis Japonica. Amer. four, Hyg., Monographic Series, No. 3. FISCHOEDER, F. 1901. Die Paramphistomiden der Satgethiere. Zool. Anz., 24: Zool. Anx., 24:365-375. 1903. Die Paramphistomiden der Saugethiere. Zool. Jahrb. f. Syst. Geog. und Biol., 17:485-660, 11 pls., 17 text-figs. Fuxul, T. 1929. Studies on Japanese Amphistomatous Parasites, with Revision of the Group. Jap. Jour. Zool., 2:219-351, 45 text-figs. LIFE HISTORY OF COTYLOPHORON—BENNETT 99 IsHu, Y. 1934. Studies on the Development of Fasciolopsis buski, Part I, Jour. Med. Assoc. Formosa, 33:349-378, 1 pl., 10 tables, 1 text-fig. 1934a. Studies on the Development of Fasciolopsis buski, Part II, Jour. Med. Assoc. Formosa, 33:379-390, 1 pl., 2 tables. 1934b. Studies on the Development of Fasciolopsis buski, Part III. Jour. Med. Assoc. Formosa, 33:391-412, 1 pl., 2 charts. Jounson, J. C. 1920. The Life Cycle of Echinostoma revolutum (Froelich). Univ. Calif. Publ. Zool., 19:335-388, pls. 19-25, 1 text-fig, Kruii, W. H. 1932. Studies on the Life History of Cotylophoron cotylophorum (Fischoeder, 1901) Stiles and Goldberger, 1910. Jour. Parasitol., 19: 165-166. 1934. Life History Studies on Cotylophoron cotylophorum (Fischoeder, 1901) Stiles and Goldberger, 1910. Jour. Parasitol., 20:173-180, 1 text-fig., 1 table: Kru.i, W. H., and Price, HELEN F. 1932. Studies on the Life History of Diplodiscus temperatus Stafford from the Frog. Occasional Papers from Mus. of Zool., Univ. of Mich., no. 237. Lerper, R. T. 1910. The Entozoa of the Hippopotamus. Proc. Zool. Soc. London, 1:233-251, 9 text-figs. Le Roux, P. L. 1930. A Preliminary Communication on the Life Cycle of Cotylophoron cotylophorum and Its Pathogenicity for Sheep and Cattle. 16. Rep. Director Vet. Serv., Dept. Agric. Union South Africa, Pretoria, pp. 243-253, 7 figs. Leucxkart, R. 1886. Die Parasiten des Menschen. Leipzig. Vol. II, p. 72. Looss, A. 1892. Ueber Amphistomum subclavatum Rud. und seine Entwicklung. Fests. zum 70. Geburts. R. Leuckarts, Seite 147 bis 167, 2 Tafeln. Leipzig. 1896. Recherches sur les faune parasitaire de l’Egypte, I. Mem. I’Inst. Egypt., 3:1-252, 16 pls. Lyncu, J. E. 1932. The Miracidium of Heronimus chelydrae MacCallum. Quar. Jour. Micro. Sci., 76:13-33, 2 pls., 2 text-figs. McCoy, O. R. 1929. Notes on Cercariae from Missouri. Jour. Parasit., 15:199-208, 1 pl. Manter, H. W. 1926. Some North American Fish Trematodes. Ill. Biol. Monographs, 10: No. 2:1-138, 6 pls., 2 charts, 1 text-fig. MAPLESTONE, P. A. 1923. A Revision of the Amphistomata of Mammals. Ann. Trop. Med. and Parasitol., 17:114-212, 4 pls., 32 text-figs., 10 tables. Matuias, P. 1925. Recherches expérimentales sur le cycle évolutif de quelques Trématodes. Bull. Sci. de la France et de la Belgique, 59:1-124, 4 pls., 13 text-figs. Naxkacawa, K. 1917. Human Pulmonary Distomiasis caused by Paragonimus westermanit. Jour. Exp. Med., 26:297-323. 100 ILLINOIS BIOLOGICAL MONOGRAPHS O’Roxg, E. C. 1917. Larval Trematodes from Kansas Fresh Water Snails. Kans. Univ. Sci. Bull., 10 :161-180, 7 pls. OrTMANN, W. 1908. Zur Embryonalentwicklung der Echinorhynchen. Zool. Jahrb. f. Anat., 26:255-293, 2 pls. Price, HELen F. 1931. Life History of Schistosomatium douthitti (Cort). Amer, Jour. Hyg., 13:685-727, 4 pls. Rastin, K. 1933. Echinoparynphium recurvatum (Linstow, 1873) und seine Entwicklung. Biol. Spisy Vysoké Skoly Zverol. Brno. Csr., 12:1-104, 47 text-figs. REISINGER, E. 1923. Untersuchungen itiber Bau und Funktion des Excretionsapparates digenetischer Trematoden. Zool. Anz., 57:1-20, 5 text-figs. SCHAUINSLAND, H. 1883. Beitrag zur Kenntniss der Embryonalentwicklung der Trematoden. Jena. Zeit. Natur., 16:465-529, 3 Tafeln. SEWELL, R. B. S. 1922. Cercariae Indicae. Ind. Jour. Med. Res., 10, Supplement. June: 1-366. SINITSIN, D. 1931. Studien tber die Phylogenie der Trematoden. IV. Zeit. f. wiss. Zool., 138, 3:409-456, 15 text-figs. Stites, C. W., and GoLpBERGER, J. 1910. A Study of the Anatomy of Watsonius (n.g.) watsoni of Man, Bull. 60, Hyg. Lab., U. S. Pub. Health & Mar.-Hosp. Serv., Wash., 259 pp. 205 figs. StunKarp, H. W. 1923. Studies on North American Blood Flukes. Bull. Amer. Mus. Nat. Hist., 48:165-221, 11 pls. 1925. The Present Status of the Amphistome Problem. Parasitol., 17:137-148. 1929. The Parasitic Worms Collected by the American Museum of Natural History Expedition to the Belgian Congo. Bull. Amer. Mus. Nat. Hist., 58:232-291, 37 text-figs. Suzukl, 5S. 1931. Researches into the Life-History of Fasciola hepatica and its Distribu- tion in Formosa. Jour. Med. Assoc. of Formosa, 30:1418-1469, 3 pls., 13 tables. TAKAHASHI, S. 1928. Ueber die Entwicklungsgeschichte des Paramphistomum cervi. (Ab- stract) Zentralbl. f. d. ges. Hyg. Berl., 18:278. Tacsort, S. B. 1933. Life History Studies on Trematodes of the Subfamily Reniferinae. Parasitol., 25:518-545, 24 text-figs., 6 tables. Tuomas, A. P. 1883. The Life History of the Liver-Fluke (Fasciola hepatica). Quar. Jour. Micro. Sci., 23:99-133, 2 pls. Van Hatisma, J. P. 1931. Studies on the Trematode Family Strigeidae (Holostomidae) No. XXIII. Pap. Mich. Acad. Sci., 13:483-516, 2 pls., 1 table. Warp, H. B. 1916. Notes on Two Free-Living Trematodes from North America. Jour. Parasitol., 3:10-20, 1 pl. LIFE HISTORY OF COTYLOPHORON—BENNETT 101 EXPLANATION OF PLATES All figures were made with the aid of a camera lucida with the ex- ception of Fig. 80 which is a graphic reconstruction. Abbreviations Used ere tee acetabulum PGS ast Dijdas Gia c® anterior nerve rd ae Oya aoe apical papilla 1 tee DM an. basement membrane Ppae ss ae birth pore PSec i. Oe ane brain {Ls pane Chek eee cuticula hp...... Cosine caecum ere cap..... primordium of caecum GO Cx COM Fee oe central cavity LGR (Alene 5 ee caudal excretory bladder LO ers oar: CEG. ner caudal excretory duct led..... COD tear caudal excretory pore Im...... CO eee cercaria eee Cone eye: cerebral ganglion ME... 6s. CM oe sae circular muscles Mg..... COM «a. commissure Wiican ee CLG... cuticular cell NG CVsCee ee cystogenous cell fee ee CV ie cystogenous granule WU ese = acdhe (| een ductus ejaculatorius OP. ..... GN, takin ductus hermaphroditicus OS care Sevier CUS eine excretory bladder OU ee es OCs tes cstins epithelial cell Danae? Qe ole he excretory duct pe...... CNL S erune: embryo LL See Cigee eye nerve ped..... CPi ones epidermal cell, row 1 ph...... Cpa. ine epidermal cell, row 2 phe... Cp3...... epidermal cell, row 3 PUD coe eps. ..... epidermal cell, row 4 pm..... epm..... epidermal cell nucleus, row 1 DPrcne. epny..... epidermal cell nucleus, row 2 DNn...... epn;.....epidermal cell nucleus, row 3 SO eateriats epns..... epidermal cell nucleus, row 4 ty seen CS ee Keke esophagus SP ae aie es; ......esophageal cell Sina! ts Gin css ote excretory tubule Sees XP. ..6%. excretory pore Gaicaros) sus CYR re dsteks eye te Gees os flame cell TE ree DUR ert se gut Ue eee Ct ee oe genital atrium WO 6 ates ans 2D verso aie. germ ball UE o eer ae germ cell gut nucleus genital pore .genital papilla genital sucker germinal tissue hermaphroditic papilla intestine ..Laurer’s canal _lens cell lateral evagination .lateral excretory duct longitudinal muscle metraterm median evagination Mehlis’ gland nerve nerve cell nucleus nerve fiber nucleus oral plug oral sucker ovary plug primitive epithelium penetration gland penetration gland duct pharynx . pharnygeal cuticular cell pigment pars musculosa pars prostatica posterior nerve salivary gland subepithelial nucleus sensory papilla sporocyst tissue seminal vesicle tail .. testis uterus vitellaria vas deferens vas efferens 102 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE I Fics. 1-11—Developing miracidia. Scale 0.05 mm. Fic. 12.—Four-cell stage in development of the miracidium. Scale 0.03 mm. Fic. 13.—Flame cell of miracidium. Scale 0.01 mm, LIFE HISTORY OF COTYLOPHORON—BENNETT 103 PLALE 104 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE II Fics. 14-17,—Mature miracidia. Scale 0.05 mm. Fics. 18-21.—Cross sections of miracidia. Scale 0.02 mm. Fic. 22—Frontal section of anterior end of miracidium. Scale 0.02 mm. Fic. 23.—Frontal section of miracidium. Scale 0.02 mm. 105 HiPe HISTORY OF COTYLOPHORON—BENNETT PLATE II 106 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE. II Fic. 24—Miracidium in lymph duct of snail. Scale 0.03 mm. Fic. 25.—Five-day sporocyst. Scale 0.05 mm. Fic. 26.—Mature sporocyst. Scale 0.1 mm. Fic. 27—Germinal and epithelial cells in body wall of sporocyst. Scale 0.01 mm. Fic. 28—Twenty-four-hour sporocyst. Scale 0.03 mm. Fic. 29—Twelve-hour sporocyst. Scale 0.02 mm. Fic. 30.—Longitudinal section of sporocyst. Scale 0.1 mm. Fic. 31—Longitudinal section of forty-eight-hour sporocyst. Scale 0.03 mm. Fic. 32.—Body wall of sporocyst. Scale 0.05 mm. LIFE HISTORY OF COTYLOPHORON—BENNETT 107 PLATE III 108 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE IV Fic. 33.—Mature redia. Scale 0.3 mm. Fic. 34.—Frontal section of redia showing salivary glands. Scale 0.05 mm. Fro. 35.—Mature sporocyst. Scale 0.1 mm. Fic. 36.—Redia about to escape from sporocyst. Scale 0.05 mm. Fic. 37.—Frontal section of redia showing brain. Scale 0.05 mm. Fic. 38.—Sagittal section of anterior end of redia. Scale 0.1 mm. Fic. 39.—Posterior end of redia showing germ cells and de- veloping cercariae. Scale 0.1 mm. Fic. 40.—Redia in pocket of sporocyst tissue. Scale 0.3 mm. Fic. 41.—Posterior end of redia showing exhaustion of germ cells. Scale 0.1 mm. Fic. 42—Longitudinal section of immature redia. Scale 0.03 mm, LIFE HISTORY OF COTYLOPHORON—BENNETT 109 PLATE IV 110 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE V Fics. 43, 44—Longitudinal section of anterior end of imma- ture redia. Scale 0.03 mm. Fic. 45.—Lateral view of posterior end of cercaria. Scale 0.05 mm. Fic. 46.—Mature redia. Scale 0.2 mm. Fic. 47.—Oral sucker and esophagus of mature cercaria, sagittal section. Scale 0.02 mm. Fic. 48.—Mature redia. Scale 0.2 mm. Fic. 49 —Longitudinal section of anterior end of immature redia. Scale 0.03 mm. LIFE HISTORY OF COTYLOPHORON—BENNETT 111 PLATE V 112 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE. Vi .50.—Immature cercaria, dorsal view. Scale 0.05 mm. ;. 51.—Mature cercaria, ventral view. Scale 0.1 mm. ;, 52.—Immature cercaria, dorsal view. Scale 0.05 mm. .53.—Metacercaria, lateral view. Scale 0.01 mm. .54.—Cross section of tail of mature cercaria. Scale 0.04 mm. ;,55.—Frontal section of immature cercaria. Scale 0.05 mm. ;.56.—Immature cercaria, dorsal view. Scale 0.05 mm. ;,57.—Immature cercaria, ventral view. Scale 0.05 mm. 5. 58.—Mature cercaria, sagittal section. Scale 0.05 mm. 113 BENNETT PIPE. DISLORY (OF COTYLOPHORON ®) ae zs ON’ oS - ‘ 220: 20'g'0 coes PLATE VI 114 ILLINOIS BIOLOGICAL MONOGRAPHS PLATES Vit Fic. 59.—Immature cercaria, dorsal view showing pigment. Scale 0.1 mm. Fic. 60.—Excretory system, immature specimen. Scale 0.2 mm. Fic. 61—Immature cercaria, lateral view showing develop- ment of pigment. Scale 0.1 mm. Fic. 62.—Section of developing eye. Scale 0.61 mm. Fic. 63.—Cross section through genital sucker of a worm 1.17 x 0.84 mm. Scale 0.1 mm. Fics. 64,65.—Sections of developing eye. Scale 0.02 mm. Fic. 66.—Anterior end of mature cercaria, sagittal section. Scale 0.04 mm. Fic. 67.—Cross section through genital sucker of a worm 3.65 x 2.45 mm. Scale 0.5 mm. LIFE HISTORY OF COTYLOPHORON—BENNETT 115 PLATE VII 116 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE VIII Fic. 68.—Sagittal section through genital complex of a speci- men 2.5x0.72 mm. Scale 0.2 mm. Fic. 69.—Cross section through genital sucker of a specimen 2.95x1.13 mm. Scale 0.1 mm. Fic. 70.—Sagittal section of anterior end of a _ specimen 1.09x 0.39 mm. Scale 0.2 mm. I'ic.71.—Sagittal section of anterior end of a _ specimen 2.46 x 0.63 mm. Scale 0.5 mm. Fic. 72—Sagittal section of anterior end of a _ specimen 6.0x 2.75 mm. Scale 1.0 mm. Fic. 73.—Sagittal section of anterior end of a _ specimen 9.0x 2.75 mm. Scale 1.0 mm. Fic. 74.—Cross section through genital sucker of a specimen 8.0x 2.75 mm. Scale 0.1 mm. Fic. 75.—Cross section through genital sucker of a specimen 40x1.15 mm. Scale 0.1 mm. LIFE GISTORY OF COTYLOPHORON-—-BENNETT PLATE VIII 117 118 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE IX Fic. 76.—Sagittal section of a specimen of migration size, 2.46x 0.65 mm. Scale 1.0 mm. Fic. 77.—Sagittal section of a very young specimen. Scale 1.0 mm. Fic. 78.—Sagittal section of a mature specimen 2.8 x 1.26 mm. Scale 1.0 mm. Fic. 79.—Frontal section of a mature specimen 2.99 x 1.61 mm. Scale 1.0 mm. Fic. 80.—Graphic reconstruction of a mature specimen. Scale 1.0 mm, Fic. 81.—Sagittal section of a mature specimen. Scale 1.0 mm. LIFE HISTORY OF COTYLOPHORON—BENNETT 119 Pats, AGES ic : (28 Xooo MAGI FSS O52 9 Cah ee lace oN rz Frere