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A morphological and experimental study of some new dermatitis producing cercariae from Cultus Lake, B.C. Edwards, Donald Keith 1954

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A MORPHOLOGICAL AND EXPERIMENTAL STUDY OF SOME NEW DERMATITIS PRODUCING CERCARIAE FROM CULTUS LAKE, B.C. by DONALD KEITH EDWARDS. A Thesis Submitted i n P a r t i a l Fulfillment of the Requirements for the Degree of MASTER OF ARTS i n the Department of ZOOLOGY. We accept th i s thesis as conforming to the standard required from candidates for the degree of MASTER OF ARTS. Members of the Department of Zoology. THE UNIVERSITY OF BRITISH COLUMBIA. May, 1954. ABSTRACT Previous workers at Cultus Lake discovered a new species of Schistosome cercaria. In the present attempts to find this cercaria and to elucidate i t s l i f e cycle, four completely different dermatitis-producing forms were dis-covered, two of which are considered new species. The other two may be new. Three of the cercaxiae are described i n detail. These are the cercaria of Trichobilharzia adamsi n.sp., Cercaria chilliwackensis n.sp. and Cercaria 10 which may be a new species. The description includes mor-phology, behavior, snail hosts, dermatitis-producing a b i l -i t y , and observations on the sporocysts of these forms. A l l were found to he capable of producing Schistosome derm-a t i t i s . Therefore two and possibly three more cercariae have been added to the l i s t of known dermatitis-producers. The three cercariae were found in specific areas along the north-west shoreline of Cultus Lake. Attempts were made to complete the l i f e cycle of the three cercariae. Two approaches were adopted. Animals were trapped within the areas at which the cercariae were found, but examination showed that they didnot possess adult Schistosomes. Laboratory experiments were carried out i n which animals were subjected to the various cercariae and later examined for adult worms.-An immature female worm was recovered from a domestic duck which had been exposed to cercariae. The worm, Trichobilharzia adamsi, i s described as a new species. Part of the l i f e cycle of this trematode is described. The domestic duck was established as a def-initive host under experimental conditions. The specific definitive host of the trematode at Cultus Lake was not determined. The cercaria of T.adamsi i s placed in the "ocellata group" on the basis of i t s morphology. Cercaria c h i l l i - wackensis i s placed along with Cercaria do.uthi.tti i n the " d o u t h i t t i group". Cercaria 10 i s very s i m i l a r to the cercaria of Gigantobilharzia huronensis. and i s placed with the l a t t e r i n the "spindalis group". A l l three of the cercariae described possess p a p i l l a r spination. These spines have been described only once i n the past as occur-i n on a dermatitis-producing cercaria. The p a p i l l a r spin-ation i s described i n d e t a i l . The spines are located i n s i m i l a r patterns on the bodies of the three cercariae. This pattern i s carried through to the adult of T.adamsi. Evidence i s given of the occurance of p a p i l l a r spination on cercariae elsewhere i n the Province. A modification of the perfusion technique of Yolles et a l i s described. This was used f o r the investiga-t i o n of the experimental animals f o r adult worms. Further, a new technique using the side-arm f l a s k of McMullen and Beaver i s described. The apparatus concentrates Schisto-some cercariae i n large numbers i n a r e l a t i v e l y small area. ACKNOWLEDGEMENTS The survey o f the Schistosome d e r m a t i t i s problem at C u l t u s Lake and re s e a r c h on the irematoda found t h e r e i n , was made p o s s i b l e by a grant from the dominion Department of P u b l i c H e a l t h . The author i s g r e a t l y indebted to Dr.James R.Adams, d i r e c t o r of the survey, who suggested t h i s problem and made a v a i l a b l e l a b o r a t o r y and other f a c i l i t i e s . Ur.Adams was always ready to a s s i s t i n times o f d i f f i c u l t y and gave much of h i s v a l u a b l e time i n a s s i s t i n g with the p r e p a r a t i o n o f the manuscript. In a p p r e c i a t i o n , a s p e c i e s d e s c r i b e d h e r e i n has been g i v e n Dr.Adams 1 name. A p p r e c i a t i o n i s g r a t e f u l l y acknowledged to D r . I . McTaggart-Cowan, Head of the Dept. of Zoology, who read the f i n a l rough copy o f the manuscript. The author's a p p r e c i a t i o n i s expressed to M a r j o r i e Jansch, who a s s i s t e d i n f i e l d work and l a b o r a t o r y experiments and who w i l l i n g l y allowed h e r s e l f to be used as a su b j e c t f o r Schistosome d e r m a t i t i s experiments. Thanks are due to the p r o p r i e t o r s o f the C u l t u s Lake Resort who cooperated i n providing p a r k i n g space and a motor-boat f o r f i e l d work, to Dr.H.Van der S c h a l i e o f the U n i v e r s i t y o f Michigan who i d e n t i f i e d the s n a i l h osts, and to the many persons who were i n d i r e c t l y connected with the i n v e s t i g a t i o n . fo h i s wife, the author would l i k e to express h i s a p p r e c i a t i o n f o r her v a l u a b l e a s s i s t a n c e o f f e r e d on many occasions i n c o l l e c t i n g s n a i l s i n the f i e l d . CONTENTS. Page. INTRODUCTION. .1 Geographical D i s t r i b u t i o n of Schistosome Dermatitis 4 Background of the Problem .6 METHODS AND APPARATUS 9 Methods of Study of the Larval Forms 9 Methods Used i n Life - c y c l e Studies 15 MORPHOLOGY OF THE CULTUS LAKE TREMATODES 24 Triehobilharzia adamsi- Cercaria 24 - Ovum, Miracidium and Sporocysts....32 - Adult Female Worm 34 Cercaria 16A 43 Cercaria chilliwackensis ...47 Cercaria 10 58 PAPILLAR SPINATION 74 TAXONOMIC DISCUSSION 79 Taxonomy of the Adult T.adamsi 79 Taxonomy of the Cultus Lake Cercariae 80 ECOLOGICAL RELATIONSHIPS OF THE THREE TREMATODES 85 SCHISTOSOME DERMATITIS EXPERIMENTS 90 DISCUSSION 94 SUMMARY 97 page. LITERATURE CITED 100 LIST OF PLATES. F o l l o w i n g : PLATE 1 - C e r c a r i a "Concentrator" Technique .page 17 PLATE 11-Adult Female T.adamsi ..page 42 PLATE 111-Cercaria of T.adamsi ' p l a t e 11 PLATE lV - S p o r o c y s t s of T.adamsi . . p l a t e 111 PLATE V - C e r c a r i a c h i l l i w a c k e n s i s .....page 57 PLATE Vl - S p o r o c y s t s of C . c h i l l i w a c k e n s i s p l a t e V PLATE V l l - C e r c a r i a 10 page 73 PLATE V l l l - S p o r o c y s t s of C e r c a r i a 10 . . p l a t e V l l PLATE lX-Contour Map of C u l t u s Lake page 89 PLATE X - R e l a t i v e P o s i t i o n s of S p e c i f i c C o l l e c t i n g Areas p l a t e ]X A MORPHOLOGICAL AND EXPERIMENTAL STUDY OP SOME ± 9 NEW DERMATITIS PRODUCING CERCARIAE FROM CULTUS LAKE, B.C. INTRODUCTION The dermal r e a c t i o n t o the p e n e t r a t i o n o f c e r t a i n Schistosome c e r c a r i a e i s known as Schistosome d e r m a t i t i s . I t has been the sub j e c t of* much i n v e s t i g a t i o n i n the p a s t . The problem has been s t u d i e d both from the p o i n t o f view o f Zoology and Medicine. Schistosome d e r m a t i t i s , more commonly known as "swimmer's i t c h " , i s c h a r a c t e r i z e d by an i n t e n s e i t c h i n g s e n s a t i o n which occurs from f i v e to f i f t e e n minutes a f t e r the s k i n has been su b j e c t e d to the c e r c a r i a e o f c e r t a i n Schistosomes. The i r r i t a t i o n g r a d u a l l y subsides over a p e r i o d o f approximately one h a l f hour, a f t e r which time minute macules may appear on the area o f the s k i n which was exposed to the c e r c a r i a e . In approximately twenty-four hours the i t c h i n g again may become apparent and i s o f t e n more i n t e n s e than the f i r s t phase. By t h i s time the macules have become d i s t i n c t l y papular and i f s u f f i c i e n t l y c l o s e together may have produced c o l l e c t i v e l y a l a r g e erythema. The i n t e n s i t y o f the i t c h i n g : s e n s a t i o n i s very much i n -creased with l i g h t rubbing on the area though i n i t i a l l y the rubbing has no gre a t e f f e c t . The phenomenon i s one of sens-i t i z a t i o n and though f i r s t exposuresof the s k i n to these c e r c a r i a e r e s u l t i n no d e r m a t i t i s , subsequent i n f e c t i o n s pro-duce I n c r e a s i n g l y severe r e s u l t s . From a medical standpoint the d e r m a t i t i s seems im-portant i n that secondary i n f e c t i o n may a r i s e as the r e s u l t of s c r a t c h i n g of the i r r i t a t i n g papules. F u r t h e r , occas-i o n a l severe a l l e r g i c r e a c t i o n s to the f o r e i g n p r o t e i n s of the c e r c a r i a e occur, which are so i n t e n s e as to incapac-2. i t a t e the victim. There i s no evidence that these cer-cariae are able to mature i n a human host, nor have they been demonstrated i n the viscera of man. However, Penner (1941) showed that Cercaria d o u t h i t t i may migrate i n large numbers to the lungs of the rhesus monkey, and O l i v i e r (1953) also demonstrated that the cercariae of some im-portant dermatitis producers may reach the lungs of monkeys. Future experimentation with mammalian forms may reveal facts of more concern to medical science. The term "Schistosome dermatitis" was f i r s t pro-posed by Cort(l928). His discovery of the relationship between aquatic s n a i l s and the dermatitis, i n Michigan, was accidental. While sorting snails i n a bucket he con-tracted an intense i t c h on the arm which was i n contact with the water. The cercariae escaping from these s n a i l s were experimentally demonstrated to be the causative organ-isms of the dermatitis. They were supposedly i d e n t i f i e d as Cercaria elvae M i l l e r , but at a l a t e r date t h i s c e r c a r i a was recognized as having been erroneously i d e n t i f i e d and was found to have been C.stagnicolae Talbot. Cort predicted at t h i s time that i n a l l p r o b a b i l i t y other related forms would be found which would be capable of producing a derm-a t i t i s , and that, as a result of t h i s , the dermatitis would probably be found i n many parts of the United States. At a l a t e r date Cort(1928 b) produced experimental derm-a t i t i s with three additional cercariae, c e r c a r i a d o u t h i t t i Cort 1914, a mammalian form, and two other cercariae which were at the time unnamed. In 1930 Vogel i n Europe produced dermatitis experimentally with Cercaria o c e l l a t a La Valette St.George. This author described the phenomenon as "cer-c a r i a l dermatitis" (cercarien-dermatitis). Cort however, believes that t h i s term i s too broad, since only the Schist-3. osome cercariae are implicated i n t h i s type of dermatitis. The two innominate cercariae mentioned by Cort i n 1928 with reference to his work with experimental derm-a t i t i s remained unnamed u n t i l 1936 when Talbot described t h e i r morphology. They were named Cercaria stagnicolae and Cercaria physellae. and with Cercaria elvae they constitute the most important dermatitis-producers i n the United States and Canada today (Cort,1950). Also i n 1936, Cort and Talbot described the behavior patterns of the four American Schist-osomes which were known to be dermatitis-producers. The European form, Cercaria o c e l l a t a . was considered by Cort on the basis of behavior to be d i s t i n c t from C.elvae. In summary then, at the end of 1936 there were i n a l l f i v e species of Schistosome cercariae known to science which were capable of producing a dermatitis i n man. How-ever, some workers (Szidat and Wigand) at t h i s time consid-ered another cercaria, C.pseudocellata, as being very sim-i l a r to but not synonymous with C.ocellata. Since that time a number of authors have i n s i s t e d that c.ocellata i s a complex and i n r e a l i t y consists of the following forms based on differences i n size: C.pseudocellata Szidat and Wigand, C.neocellata Szidat and C.parocellata Szidat. The v a l i d i t y of these species i s not unanimously agreed upon. However, Cort(1950) l i s t s these cercariae tentatively, along with C.ocellata, as being d i s t i n c t species. The questionable v a l i d i t y of size as a c r i t e r i o n of species d i f f e r e n t i a t i o n has been emphasized by Neuhaus(1952) whose experimental work strongly supports his views. In 1938 Buckley reported a dermatitis from Malaya c a l l e d "sawah i t c h " and ascribed i t to the cercaria of Schistosoma spindalis Montgomery 1906. 4. The number of known dermatitis-producing cerc-ariae has been steadily increasing during the past t h i r t y years. Cort's 1950 publication on the status of the sub-ject l i s t e d a l l of the cercariae which were known and sus-pected at that time to be dermatitis-producers. Eighteen cercariae were included. Of these Cort states that many may be synonyms and the l i s t i n g i s tentative. Much work i s necessary on l i f e - c y c l e studies before the position of many of these cercariae can be d e f i n i t e l y established. Of the forms l i s t e d only f i v e are d e f i n i t e l y described as being d i s t i n c t species. The v a l i d i t y of the others i s question-able. Since the publication of Cort's paper at least s i x more dermatitis-producing cercariae which are considered new, exclusive of those described i n this work, have been found. Of these, two are found i n marine s n a i l s . Najim (1951) worked out the l i f e - c y c l e of Gigantobilharzia huron-ensis and described the cercaria as a dermatitis-producer. Simmons, Martin and Wagner(1951) reported that they had found two new dermatitis-producing cercariae i n southern C a l i f o r n -i a , but no description of these was given. Wu(l953) has described the dermatitis-producing cercaria of T r i c h o b i l - harzia cameroni and she has also elucidated the l i f e - c y c l e of t h i s form. Geographical D i s t r i b u t i o n of Schistosome Dermatitis. As interest i n the problem of Schistosome derm-a t i t i s increased following Cort's i n i t i a l discovery of the b i o l o g i c a l relationships involved, other workers f a r re-moved from the focus i n Michigan began to undertake invest-igations of the problem. Schistosome dermatitis has been reported from almost a l l regions of the world. (Sort(1936 a) described the contemporary d i s t r i b u t i o n of the dermatitis i n Europe i n 1936. A dermatitis coinciding with the type found i n the United States was reported from Wales (where C.ocellata was d e f i n i t e l y implicated). Other reports came from East Prussia, Switzerland, the Holstein Lake region south of K i e l , and France. Further, a dermatitis was reported from a lake i n H a i t i which was almost certainly caused by Schistosomes. Cort, i n his 1950 paper on the status of Schisto-some dermatitis, summed up the d i s t r i b u t i o n as was known at that time. From A f r i c a there have been no confirmed reports of t h i s dermatitis, but Porter(l938) found C.ocellata i n the Orange Free State. It seems probable that the dermatitis exists i n some regions on that continent. In Asia, Schisto-some dermatitis exists*as "sawah i t c h " i n the Malay States and i t has been reported as "kabure" from Japan. Two other unconfirmed reports indicate the presence of the dermatitis i n India and Burma. It has been reported also from Austral-i a and New Zealand. In the Western Hemisphere the dermatitis has been confirmed i n North America only. However, there are reports of a s i m i l a r dermatitis from B r a z i l . In Cuba i t i s known as BE1 Caribe". However, the position of Schist-osome cercariae as the causative agents has not been defin-i t e l y established. There have been unpublished reports of a similar dermatitis from Mexico. The author recently re-ceived a report of a dermatitis from Fairbanks, Alaska. Although i t i s not known for certain, t h i s i s probably caused by Schistosome cercariae. At the time of Cort'a publication i n 1950 Schist-osome dermatitis was also known from Minnesota, Wisconsin, 6. Iowa, North Dakota and other American States as f a r south as F l o r i d a . Hunter et al(l949) gave an account of the derm-a t i t i s found within the c i t y l i m i t s of Seattle, Washington. Recently, Macy(1952) summarized our knowledge of dermatitis-producers i n the States of the U.S. west coast. Cort declares that Canada possesses the largest endemic areas of Schistosome dermatitis i n the world.' In 1936 he reported that Saunders found dermatitis near Saska-toon, Saskatchewan, and attributed i t to C.stagnicolae. Saunders also reported that he had obtained cercariae of the "elvae group" from Paul Lake, B.C., and that he posses-sed substantiated reports of dermatitis i n the Peace River d i s t r i c t . He also claimed unconfirmed reports from Vancouver Island. McLeod(l940) and McLeod and Little(1942) reported that Cercaria elvae, C.stagnicolae, C.physellae and C.dermo-lestes were a l l responsible for l o c a l outbreaks of the derm-a t i t i s at Clear Lake, Manitoba. Wu(l953) published the l i f e -cycle of T r i c h o b i l h a r z i a cameroni, the cercariae of which, were responsible f o r dermatitis outbreaks i n the Province of Quebec. Background of the Problem; The frequency of reports of a high incidence of Schistosome dermatitis at Cultus Lake during the warm summer months led to the establishment of a research grant by the Dominion Department of Public Health, thereby enabling investigations to be carried out on a f u l l - t i m e basis. Work i n 1951, under the d i r e c t i o n of Dr.J.R.Adams, resulted i n the c o l l e c t i o n of large numbers of snails from the resort area of Cultus Lake, by S.M.Sager and M.Thorn. In the labor-atory some of these snails gave off Cercaria physellae and C.stagnicolae, both dermatitis-producers. In addition to these forms another cercaria, a dermatitis-producer also, was found and was considered tentatively to be a new species This cercaria, which possessed f i v e pairs of flame c e l l s i n the body, was characterized mainly by the presence of d i s t i n c t i v e and unique " p a p i l l a r spines" on the body. These structures have previously been described only once on a dermatitis-producing Schistosome cercaria. On this basis and upon consideration of other morphological differences between the l o c a l form and other cercariae, the former was considered new to science. During the summer of 1952 the survey work was taken over by the author. However, at this time attention was turned away from Gultus Lake i n order to carry out a com-prehensive survey of the Schistosome dermatitis problem i n the Okanagan VaU'ey. As a result further studies of the situation at Gultus Lake were not made u n t i l the completion., of the Okanagan survey i n the F a l l of 1952. With the knowledge of the probable existence of a new species of cercaria at Gultus Lake i n mind the author began the investigation with the intention of working out i f possible the l i f e - c y c l e of t h i s form. Attempts were made to trap mammals and to examine them for the presence of adult Schistosomes with the hope that the adult worm of the unknown cercaria would be discovered.' A l l animals so examined were found to be negative i n t h i s respect. With the coming -of June, 1953, snails were being continuously collected and their, l a r v a l trernatode infections 8 -studied. The si t u a t i o n was c a r e f u l l y watched for the appear-ance of the new cercaria. As the summer proceded through July the cercariae described i n th i s work appeared, but no cercaria was confirmed as being the previously described new form. Instead, more than one cercaria was found which possessed p a p i l l a r spination, the ch a r a c t e r i s t i c which had been described as unique for the former unknown cerc a r i a . Of these, four were confirmed to be capable of producing Schistosome dermatitis, and therefore each was considered to be pot e n t i a l l y the unknown cercaria which had previously been described. Later comparisons seemed to indicate, how-ever, that these four cercariae had not been seen before at Cultus Lake. A discussion of the possible reasons for the f a i l -ure to discover the o r i g i n a l cercaria i s given toward the end of the present work. METHODS AND APPARATUS T h i s study of the three C u l t u s Lake trematodes was d i v i d e d i n t o two c a t e g o r i e s : ( l . M o r p h o l o g i c a l and h o s t - r e l a t i o n s h i p s t u d i e s were made of the c e r c a r i a e and s p o r o c y s t s . (2.Attempts were made to work out the l i f e - c y c l e of the three Cultus Lake c e r c a r i a e . Methods of Study of the L a r v a l Forms; A - C o l l e c t i o n and C u l t u r i n g of S n a i l Intermediate Hosts: A l l s n a i l c o l l e c t i o n s were made w i t h i n a r e s t r i c t e d a rea along the north-west shore of C u l t u s Lake (PlateUX). Due to the nature o f the undergrowth along the s h o r e l i n e i n t h i s r e g i o n i t was necessary to proceed from one p o i n t to another by means of a small boat. Examination of the beach • f o r s n a i l s was greatly, hindered by the presence i n the s h a l -low water o f l a r g e numbers of dead t r e e s and t a n g l e s of dead undergrowth. In many i n s t a n c e s s n a i l s were found c l i n g i n g to t h i s submerged wood and i n some areas they seemed to p r e f e r t h i s to the small rocks c o n s t i t u t i n g the bottom. During the e a r l y p o r t i o n of the summer the s u r f a c e of the l a k e was u s u a l l y s u f f i c i e n t l y calm to allow c l e a r t v i s i o n o f - t h e bottom i n the shallow water. However, l a t e r i n the summer the l a k e s u r f a c e on many occasions was rough-ened by a b r i s k wind, making c l e a r v i s i o n of the bottom i m p o s s i b l e . T h i s d i f f i c u l t y was overcome by the c o n s t r u c t i o n o f a glass-bottomed viewer with a window 92. v 6- i n c h e s . 8 4 T h i s gave a range of v i s i o n i n two f e e t of water o f approx-imat e l y twice those dimensions. Admittedly, fewer s n a i l s 10. could be co l l ec ted i n th i s manner than could be co l l ec ted when the surface was calm due to the l i m i t e d degree of v i s i o n through the window. The sna i l s were co l l ec ted into quart sealers with a maximum of 50 or 60 i n each j a r . They were safe ly kept i n th i s concentration u n t i l , the fol lowing day. The temper-ature of the lake water at the shore l i n e was always taken with each c o l l e c t i o n of s n a i l s . In the laboratory the sna i l s were washed thoroughly i n tap water and put into quart sealers i n the concentration of f ive to s ix per j a r . The sealers were ha l f f i l l e d with tap water which had been allowed to . s tand approximately three or four days. It was found that water d i r e c t from the tap could not be used since i t k i l l e d the sna i l s within a few days. Some experiments were undertaken to determine the reason for t h i s . It was learned from the author i t i e s that chlorine i s added to the c i t y water i n the form of a c h l o r -amine and th i s would not d iss ipate upon standing. Therefore some other explanation had to be found to explain why the tap water became to lerab le to the sna i l s upon standing. The resul t s of the experiments showed that very probably the c r i t i c a l factor was one of pH and that the tap water was too a c i d i c for s n a i l s u r v i v a l . When the water was allowed to stand, the pH increased s l i g h t l y to a neutral po in t . The ro le of the pH i n a f fec t ing sna i l s was v e r i f i e d by the ad-d i t i o n of basic sa l t s to water obtained d i r e c t l y from the tap i n order to increase the pH to .a point between 7 and 8. Juveni les , which are more susceptable to pH var ia t ions than adults , were kept successful ly i n water so treated . 11. In the past, collections of snails have been fed by adding lettuce to the jars(Sager,1950). However, i t was discovered that the lettuce caused the- water i n the jar to become quite murky afte r a period of a few days. Hence a substitute was found which proved to be much more practicable. S t e l a r i a media, the common chick-weed, was used aft e r i t had been washed thoroughly i n tap water. A small amount of th i s plant was added to each sealer and the snails fed quite readily upon i t . While decaying i n the jar these leaves do not increase the t u r b i d i t y of the water. Snails were maintained i n the laboratory f o r a period of several weeks i n the above manner. In June a number of juvenile snails was collected from the same area of Cultus Lake. These were kept i n the laboratory i n gallon jars and also i n a f i v e gallon aquarium. Most of these snails., survived for a period of three months. It must be noted that i f the snails were kept i n the laboratory f o r a period exceeding one week, the water was buffered every few days by adding to the jars and aquar-i a a small amount (approximately one-eighth teaspoon) of powdered limestone. A quantity of powdered limestone was also added to the battery-jars i n which the tap water was allowed to stand. The jars of snails were examined several times each day with a hand lens to determine whether cercariae were emerging. I f cercariae were seen, the snails were taken from the jar and washed thoroughly i n tap water to remove any p o s s i b i l i t y of the trematodes clinging to the s h e l l s . The snails were then isolated by placing each one 12. i n a 1 x 2 inch v i a l with tap water which had been stand-ing f o r at least four days. The cercariae seen i n i t i a l l y i n the quart sealer would be found l a t e r within one or more of the v i a l s . The s n a i l responsible f o r them was thus singled out. Emergence of the cercariae could be acceler-ated by changing the water i n the v i a l or by shining a strong l i g h t into i t . When the snails giving o f f the cercariae were isolated, each was placed i n a larger container with a small amount of chick-weed. These were then placed i n a shallow trough which contained running water, to lower the temperature of the s n a i l ' s water. The lower temperature both retarded decomposition of the chick-weed and slowed down the emergence of the cercariae u n t i l they were needed for examination and l i f e - c y c l e experiments. B-Methods of Studying the Cercariae; A l l cercariae were studied a f t e r natural emergence from the s n a i l host. On some occasions i t was found that c e r c a r i a l emergence could be induced by changing the water i n the j a r . This phenomenon was reported by Taylor and Baylis i n 1930(Cort and Talbot, 1936) with reference to the emergence of Cercaria o c e l l a t a . Further, i t was discovered that emergence could be effected by shining a beam of l i g h t through the jar containing the s n a i l host. In one instance, • the number of Cercaria chilliwackensis present i n the s n a i l jar at mid-afternoon, a f t e r having remained constant f o r three hours, was increased from about s i x to approximately three dozen within a half hour by d i r e c t i n g the beam of a microscope lamp through the j a r . It was not determined i n t h i s instance whether the emergence was the result of a 13. l i g h t i n t e n s i t y i n c r e a s e or merely the r e s u l t of a pos-s i b l e r i s e i n temperature of the water i n the j a r . The e f f e c t of l i g h t upon the emergence o f c e r c a r i a e was stud-i e d ' by 0 1 i v i e r ( l 9 5 1 ) at which time he noted a d e f i n i t e c o r r e l a t i o n betvireen c e r c a r i a l emergence and the hours of d a y l i g h t f o r the c e r c a r i a e of Schistosomatium d o u t h i t t i . The c e r c a r i a e were s t u d i e d and d e s c r i b e d i n d e t a i l . They were examined with v a r i o u s powers of the microscope i n order to a s c e r t a i n the morphological d e t a i l s and to o b t a i n measurements. Examination under o i l - i m m e r s i o n was necessary i n order to observe the organ systems and to l o -cate and d e s c r i b e , p a r t i c u l a r l y , the p a p i l l a r s p i n a t i o n . C e r t a i n d e t a i l s of the behavior of these c e r c a r i a e c o u l d be determined by microscopic examination. Other d e t a i l s such as p r o p o r t i o n a l appearances of the v a r i o u s p a r t s of the c e r c a r i a e were observed. A f t e r studying these l a r v a e a number of times s u f f i c i e n t experience was gained to allow r e c o g n i t i o n of them upon low m a g n i f i c a t i o n . The c e r c a r i a e were a l s o s t u d i e d from the p o i n t of view of t h e i r free-swimming behavior. The importance of swimming behavior as a s p e c i f i c c h a r a c t e r i s t i c was estab-l i s h e d by Talbot(1936). A v i a l c o n t a i n i n g f a i r numbers of the Cultus Lake c e r c a r i a e was examined i n a beam of l i g h t i n a dark room to a s c e r t a i n the degree of r e a c t i o n , i f any, to l i g h t . T h e i r r e a c t i o n to g r a v i t y was a l s o noted, as w e l l as the body p o s i t i o n while r e s t i n g . The behavior of the c e r -c a r i a e was observed while they were under a c o v e r - g l a s s i n a wet.mount p r e p a r a t i o n . The taxes o f ' t h e c e r c a r i a e and t h e i r c h a r a c t e r i s t i c swimming behavior were most c l e a r l y s t u d i e d by u t i l i z a t i o n of the side-arm f l a s k " c o n c e n t r a t o r " 14. described below. By this means fa i r ly large numbers of the cercariae could be easily studied "en masse". As with ' the ease of the morphology of the cercariae famil iarity resulted in the abi l i ty to recognize one or two of these species by means of. their swimming behavior. The dermatitis-producing ab i l i t i e s of these cerc-ariae were studied. For a detailed analysis of the tech-niques used see under "Schistosome dermatitis Experiments'*. Cercariae were preserved by adding to the water an equal amount of hot 30% formalin. C-feethods of Studying the Sporocysts; When an infected snail died i t was dissected as soon as possible under the binocular microscope. The spor-ocysts were measured and photographed under high magnifica-tion with a monocular microscope. In two instances the snail was dissected "in vivo" in order to observe the spor-ocysts and cercariae in the l ive state. Cercariae were thus observed emerging from the sporocysts. Before l ive sporocysts could be measured or photographed they had to be k i l l e d to stop a l l motion. This was effected by touching to the sporocyst mass a drop of 30% formalin on the end of a dissecting needle. It was found more expedient to photograph the sporocysts than to draw them. In the snail tissue they were always found in a tangled mass and i t was very d i f f i cu l t to trace any one sporocyst along i t s length for any appreciable distance. 15. Methods Used In L i f e - c y c l e Studies: In attempting to solve the l i f e - c y c l e of the Cultus Lake trematodes the cycle was attacked from two dif f e r e n t points. Therefore these developmental studies may be considered under two headings: (l.Investigations of animals i n the f i e l d which could possibly act as the d e f i n i t i v e host. (2.The carrying out of i n f e c t i o n experiments i n the laboratory i n which animals were subjected to the cercariae. In the f i r s t instance the possible host i s known while the potential parasite i s unknown. In the second case the re-verse condition exists, the parasite being the known factor. A-Trapping; Since the unknown, 1951 cerca r i a possessed f i v e pairs of flame c e l l s i n the body i t was similar, i n t h i s respect to Cercaria douth i t t i Cort 1914. Price(l93l) worked out the l i f e - c y c l e of C.douthitti i n small mammals, i . e . mice. Schistosomatium do u t h i t t i became the only dermatitis producer which was known to occur i n mammals. It was there-fore considered l i k e l y that the Cultus Lake cercaria would be found to undergo development i n small mammals and traps were set out for these. The f i r s t series of traps were set out during the f a l l of 1952 and the spring of 1953. The area covered-was named by the author the "beach" area f o r the sake of d i f f e r e n t i a t i o n (Plate X. ). A l l traps used were mouse-traps, with the exception of a group of larger spring-traps used to catch Mink. The mouse-traps were baited with walnuts. The larger spring-traps were arranged i n a small 16. c i r c l e with a dead f i s h suspended above the center of the c i r c l e approximately three feet from the ground. A l l traps were set within a few yards of the shoreline, except i n one instance. In the l a t t e r case the traps were extended to approximately 30 feet from shore i n an attempt to vary, the y i e l d . The trapping attempts outlined above yielded 49 small mammals. These included 35 Peromyscus spp., 2 Mic-rotus spp., 11 Sorex spp. and one Mink. The animals were examined i n the laboratory f o r adult Schistosomes. A l l were found to be negative i n t h i s respect. Two methods of exam-ination were adopted: (l.The i n t e s t i n a l mesenteries were stretched under a binocular microscope and examined; the l i v e r was macerated and examined. (2.The faeces or i n t e s t i n a l contents were examined for ova by using the side-arm f l a s k technique. During the summer months of 1953 the author learn-ed that the Schistosome cercariae which possess p a p i l l a r spination occured i n snails located farther southward along the beach (Plate X J ). None whatever emerged from snails collected from the "beach" area. In view of t h i s , traps were set on August 31, 1953, i n Area B from which the great-est number of p a p i l l a t e d cercariae were recovered. The traps yielded only 4 Peromyscus and 2 Sorex spp. Examination proved these to be devoid of adult Schistosomes. No adult Schistosomes were found i n the animals caught i n the f i e l d , and as a result the natural host of the parasites could not be established. 17. B-Methods Used In Infection Experiments: Infection experiments were greatly hampered by a lack of material. This was due to the extremely small percentage of snails infected with the cercariae i n ques-t i o n . Methods had to be adopted which would increase the number of cercariae i n the water used for i n f e c t i o n exper-iments. Side-arm Flask Concentrator; I n i t i a l attempts to in f e c t white mice with cer-cariae were made by holding the mouse manually, with the t a i l immersed i n a v i a l of water containing the organisms. However, i n t h i s p osition the mouse was usually very active and disturbed the water i n the v i a l with movements of the hind feet and t a i l , as well as almost invariably defecating into the v i a l . The animal could not be maintained i n t h i s p o sition for long periods of time. O l i v i e r and Stirewalt (1952) outlined a system f o r restraining mice for i n f e c t i o n through the t a i l . In the present instance however, a method was sought which would not only, r e s t r a i n the movements of the mouse,,but which at the same time would allow for a greater concentration of cercariae to be present near the exposed area. Concentration of the cercariae was effected as follows. A 500 ml. side-arm f l a s k (Plate 1), such as i s used i n the McMullen and Beayer technique, was f i r s t f i l l e d with water to the l e v e l D. Snails were then put into i t which were giving off the same species of cercaria. A cork E was pushed into the mouth of the f l a s k to make i t a i r -PLATE 1 A - f l a s k B - s n a i l s C-paper bag,double D - f i r s t water l e v e l E - c o r k , a i r t i g h t F-second water l e v e l G - l i g h t source H-cardboard tube I - c o r k p l u n g e r J - l a b o r a t o r y mouse K-clamp L-clamp stand M-tail-clamp,padded APPARATUS FOR EXPOSURE OF M\CE TO CERCARIAE C PLATE 1 1'8. t i g h t . T h e l e v e l o f wat e r i n t h e f l a s k was t h e n r a i s e d t o t h e s e c o n d l e v e l F by a d d i n g more w a t e r t h r o u g h the. s i d e -a r m . T h e e n t i r e f l a s k . w a s e n c l o s e d u n d e r a p a p e r b a g o f d o u b l e t h i c k n e s s w i t h a h o l e i n i t t o a l l o w t h e s i d e - a r m t o p r o t r u d e t h r o u g h . A s t r o n g l a m p was s h o n e i n t o t h e a r m . The a p p a r a t u s w o u l d now u t i l i z e t h e c h a r a c t e r i s t i c n e g a t i v e g e o t a x i s a n d p o s i t i v e p h o t o t a x i s o f t h e c e r c a r i a e e m e r g i n g f r o m t h e s n a i l s . T h e s e became c o n c e n t r a t e d i n t h e s i d e - a r m . M i c e w e r e s u b j e c t e d t o t h e c e r c a r i a e by t h e f o l -l o w i n g m e t h o d . T h e mouse was p u t i n t o a c a r d b o a r d t u b e w i t h a s m a l l h o l e a t t h e b o t t o m a l l o w i n g t h e t a i l t o p r o t r u d e t h r o u g h . A c o r k p l u n g e r was t h e n p u s h e d t h r o u g h t h e t u b e o n t o p o f t h e mouse t o s u c h a p o i n t t h a t t h e a n i m a l became s u f f i c i e n t l y c o n f i n e d t o r e s t r a i n i t s m o v e m e n t s . M o v e m e n t s o f t h e t a i l w e r e r e d u c e d t o a m i n i m u m by a p p l y i n g a s m a l l c l a m p M t o t h e b a s e o f t h e t a i l . The c l a m p was p a d d e d o n t h e i n s i d e w i t h a b s o r b e n t c o t t o n . T h e mouse a n d t u b e w e r e h e l d i n p l a c e a b o v e t h e s i d e - a r m by means o f a c l a m p s t a n d , a n d t h e t a i l o f t h e a n i m a l was p l a c e d w i t h i n t h e s i d e - a r m o f t h e f l a s k . T h i s a p p a r a t u s ' a l l o w e d l o n g e r p e r i o d s o f m o t i o n l e s s e x p o s u r e o f t h e mouse t o t h e c e r c a r i a e a n d t h e a p p a r a t u s c o u l d be l e f t f o r p e r i o d s o f t i m e w i t h o u t a t t e n t i o n . A n o t h e r o b v i o u s a d v a n t a g e o f t h i s t e c h n i q u e l i e s i n t h e f a c t t h a t t h e c e r c a r i a e become c o n c e n t r a t e d i n t h e r e g i o n o f i n t e n d e d e x p o s u r e o f t h e m o u s e , due t o t h e t a x e s o f t h e f o r m e r . The a p p a r a t u s may be u s e d v e r y e f f i c i e n t l y f o r s e p a r a t i n g d o u b l e i n f e c t i o n s ( i . e . S c h i s t o s o m e s a n d S t r i g e i d s ) w h e r e t h e d e g r e e o f r e s p o n s e t o l i g h t d i f f e r s b e t w e e n t h e two t y p e s o f c e r c a r i a e . 1 9 . A n i m a l s U s e d I n E x p e r i m e n t s ; A l l a n i m a l s u s e d w e r e k n o w n t o be f r e e o f S c h i s t -osome i n f e c t i o n s . T h e y h a d b e e n r a i s e d u n d e r k n o w n c o n d i -t i o n s p r e v i o u s t o t h e e x p e r i m e n t s . A f t e r t h e m i p e h a d b e e n s u b j e c t e d t o c e r c a r i a e f a e c a l c h e c k s r e v e a l e d t h a t t h e s e a n i m a l s w e r e p a r a s i t i z e d by a t a p e - w o r m , H y m e n o l e p i s . T h i s h o w e v e r , w o u l d n o t a f f e c t i n a n y way t h e v a l i d i t y o f t h e r e s u l t s . P e k i n d u c k l i n g s r a n g i n g i n a g e f r o m one week t o o n e m o n t h w e r e e x p o s e d by a l l o w i n g t h e m t o s t a n d i n w a t e r c o n t a i n i n g t h e c e r c a r i a e . T h i s m e t h o d was a d o p t e d b y T a l b o t ( 1 9 3 6 ) i n h i s a t t e m p t s t o i n f e c t d u c k s w i t h C e r c a r i a e l v a e ; C . s t a g n i c o l a e a n d C . p h y s e l l a e . T a l b o t u s e d a g r e a t e r amount o f w a t e r t h a n d i d t h e a u t h o r . Two p i g e o n s w e r e e x p o s e d t o c e r c a r i a e b y s t a n d i n g t h e m i n s h a l l o w w a t e r c o n t a i n i n g t h e o r g a n i s m s . T h e w a t e r was a p p r o x i m a t e l y one a n d o n e h a l f i n c h e s i n d e p t h . F u r t h e r , one o f t h e p i g e o n s was g i v e n a. f e w c e r c a r i a e by i n t r a p e r i -t o n e a l i n j e c t i o n . W h i t e m i c e w e r e e x p o s e d t o t h e c e r c a r i a e t h r o u g h t h e t a i l , a s m e n t i o n e d o n p a g e 1 7 . One G u i n e a p i g was u s e d i n t h e e x p e r i m e n t s . C e r -c a r i a e w e r e a p p l i e d t o t h e i n q u i n a l r e g i o n o f t h e a n i m a l a n d a f e w w e r e a d m i n i s t e r e d o r a l l y . 20. Methods of Examination of Animals: The animals which had been subjected to cercariae were examined f o r the presence of adult worms while s t i l l l i v i n g , and when they had been k i l l e d f o r dissection. At various intervals a f t e r i n i t i a l exposure faecal checks were made to determine whether Schistosome ova were present'in the faeces. This was done by using the side-arm f l a s k tech-nique(McMullen and Beaver, 1945) or by adding some faeces to tap water i n a v i a l . Occasionally the DCJ? method of f l o t a t i o n was adopted, as outlined by Chandler("Introduc-t i o n to Parasitology"). Examinations of faecal smears were also made. The faecal material was collected by allowing the animal to defecate i n a large glass j a r . A l l animals were k i l l e d with intraperitoneal Nem-butal. The optimal dosage f o r the mice was found to be .1 ml. of Veterinary Nembutal. The amount given to the duck-lings increased i n proportion to t h e i r weight. In one case -a duck weighing approximately twelve pounds was given eight mis. before i t succumbed. Experimental animals were dissected and examined for adult Schistosomes. Price(l931) dissected adults of Schistosomatium do u t h i t t i from the hepatic portal veins of mice. McLeod and Li t t l e ( l 9 4 2 ) outlined a method of dissect-ing adult Schistosomes from the serosa of the gut. Ova of S. pathlocopticum were found i n the l i v e r of infected mice by Tanabe(l923). These three si t e s are implicated i n adult Schistosome in f e c t i o n s . Therefore these regions were exam-ined i n the animals which had been subjected to the cercariae i n the present experiments. Livers of animals other than mice • 2 1 . w e r e e x a m i n e d by c o m m i n u t i n g t h e m i n c i t r a t e d s a l i n e . The e x t r i c a t e d l i v e r was c u t i n t o two o r t h r e e l a r g e p i e c e s a n d e a c h was p u t i n t o a P e t r i d i s h c o n t a i n i n g s a l i n e . H e r e , t h e l a r g e r p i e c e was t e a s e d a p a r t w i t h d i s s e c t i n g n e e d l e s . The mass t h u s f o r m e d was a l l o w e d t o s t a n d f o r a p p r o x i m a t e l y one h o u r . E a c h p i e c e o f t i s s u e was t h e n r e m o v e d w i t h f o r c e p s a n d r i n s e d i n a n o t h e r d i s h c o n t a i n i n g c i t r a t e d s a l i n e . The i n i t i a l d i s h e s p l u s t h e r i n s e d i s h w e r e e x a m i n e d u n d e r a b i n o c u l a r m i c r o s c o p e f o r a d u l t w o r m s . T h i s t e c h n i q u e r e v e a l -e d t h e o n e a d u l t S c h i s t o s o m e d e s c r i b e d i n t h i s w o r k . The l i v e r s o f t h e m i c e w e r e p e r f u s e d u s i n g a m o d -i f i c a t i o n o f t h e Y o l l e s t e c h n i q u e ( l 9 4 7 ) . I n a l l c a s e s t h e l i v e r o n l y was p e r f u s e d . I t was v e r y d i f f i c u l t t o r e m o v e t h e l i v e r o f t h e mouse w h i l e l e a v i n g t h e a o r t a c o m p l e t e l y i n t a c t . T h e r e f o r e , t h e l i v e r was l i g a t u r e d o f f , e x t r a c t e d a n d p e r f u s e d , w h i l e e x a m i n a t i o n o f t h e i n t e s t i n a l m e s e n t e r - ' i e s a n d s e r o s a was c a r r i e d o u t l a t e r . M u c h more e x p e r i e n c e w i t h t h i s t e c h n i q u e w o u l d be n e c e s s a r y i n o r d e r t o e f f e c t b o t h a s u c c e s s f u l p e r f u s i o n o f t h e l i v e r a n d t h e i n t e s t i n -a l b l o o d v e s s e l s . S i n c e t h e r e e x i s t e d no s o u r c e o f a i r - p r e s s u r e i n t h e l a b o r a t o r y t h e n e c e s s a r y p r e s s u r e was s u p p l i e d by means o f a h a n d - b u l b . A m a n o m e t e r was c o n s t r u c t e d w h i c h was c o n -n e c t e d t o t h e p e r f u s i o n a p p a r a t u s t o g i v e a n i n d i c a t i o n o f t h e amount o f p r e s s u r e w i t h i n t h e a p p a r a t u s d u r i n g p e r f u -s i o n a n d a l s o t o e f f e c t a c o n s t a n t p r e s s u r e f o r a l l e x p e r -i m e n t s . A t f i r s t i t was f o u n d • n e c e s s a r y f o r a s e c o n d p e r s o n t o u s e t h e h a n d - b u l b t o m a i n t a i n t h e p r e s s u r e . H o w e v e r a s e x p e r i e n c e was g a i n e d i t was f o u n d t h a t t h i s o p e r a t i o n c o u l d be p e r f o r m e d by t h e a u t h o r w h i l e d o i n g t h e p e r f u s i n g . T h i s 22. was done by the following method. The li g a t u r e on the vena • cava behind the diaphragm was l e f t long and when the l i v e r was removed the latter.was p a r t i a l l y suspBaded by fastening the free end of the thread i n a clamp on a stand. This a l -lowed the l e f t hand to be free to pump the bulb while the right hand inserted the needle into the hepatic sinus just below the point of attachment of the long thread. The system worked admirably and i n a very short time the, l i v e r turned creamy white. The flow through the needle was regulated by squeezing the rubber hose with the right hand and by observ-ing the l i q u i d l e v e l within the manometer. Ligaturing of the blood vessels proved d i f f i c u l t at f i r s t since these are very small and they may easily be torn with forceps or probe. This problem was overcome by using an ordinary darning needle of medium s i z e . Two threads (for double ligatures) approximately one foot long were put through the eye of the needle and t h i s was passed beneath the blood vessel to be ligatured, while the l a t t e r was held suspended with a blunt probe. After the threads were pulled through about half way the needle was removed and the threads were t i e d as f a r apart as possible. The vessel was then cut between the l i g a t u r e s . It was found that the l i v e r could be p a r t i a l l y sus-pended by a very s l i g h t p u l l upon the ligatures on the por-t a l vein and vena cava (anterior to the diaphragm). This was" useful i n removing the l i v e r from the body cavity and for general manipulation of i t . The method was used since i t was found that the diaphragm often tore too readily when i t was used for manipulating the l i v e r . 23. The i n t e s t i n a l mesenteries and serosa of a l l animals were examined by removing the intestine and view-ing i t s surface with a binocular microscope. The mesenter-ies could be c l e a r l y examined by stretching them from the intestine with dissecting needles. 24 MORPHOLOGY OE THE CULTUS LAKE TREMATODES TRICHOBILHARZIA ADAMSI  CERCARIA ( P l a t e 111) Morphology: The c e r c a r i a of T r i c h o b i l h a r z i a adamsi i s an apharyngeal, furcocercous. distome and resembles very c l o s e -l y the c e r c a r i a e o f the " o c e l l a t a group". Measurements were made of 25 c e r c a r i a e which were f i x e d i n 15$ f o r m a l i n . The Means are g i v e n with the Standard e r r o r ; body l e n g t h .2301 ± .0069 mm; body width .0802 ± .0014 mm; t a i l - s t e m l e n g t h .3413 ± .0023 mm; t a i l - s t e m width, proximal .0438 ± ,00082mm, d i s t a l .0371 ± .002 mm; f u r c a l l e n g t h .2007 * .0054 mm; f u r c a l p a p i l l a l e n g t h .0173 ± .00077 mm; o r a l sucker width .0515 ± .00071 mm; v e n t r a l sucker diameter ( f o r 20 spec-imens) .0372 ± .00062 mm; d i s t a n c e from.center of v e n t r a l sucker to p o s t e r i o r end of body .0966 ± .059 mm. The t a i l - s t e m o f the c e r c a r i a i s s l i g h t l y l o n g e r than the body. The f u r c a e are g r e a t e r than h a l f the lengith of the t a i l - s t e m . D o r s o - v e n t r a l f i n - f o l d s are present on the f u r c a e . The e n t i r e body, t a i l - s t e m and f u r c a e are uniform-l y covered with minute r e t r o r s e s p i n e s . On the body these are most obvious on the a n t e r i o r h a l f and they seem to dim-i n i s h i n s i z e as one approaches the p o s t e r i o r end of the body, making them d i f f i c u l t to observe. Those spines on the t a i l - s t e m and fu r c a e are spaced f a r t h e r apart and appear 25. somewhat more c o a r s e o r s t u r d y . P a p i l l a r s p i n e s a r e p r e s e n t o n t h e c u t i c l e o f t h i s c e r c a r i a . On e a c h s i d e , a s p i n e i s l o c a t e d a b o u t m i d -way b e t w e e n t h e mos t a n t e r i o r p o i n t o f t h e body a n d t h e j u n c t i o n o f t h e o r a l o r g a n w i t h t h e b o d y c u t i c l e l a t e r a l l y ; two a r e l o c a t e d f a i r l y c l o s e t o g e t h e r i m m e d i a t e l y p o s t e r i o r t o t h e a b o v e j u n c t i o n ; o n e i s s i t u a t e d s l i g h t l y a n t e r i o r t o t h e l e v e l o f t h e e y e s p o t . I n a d d i t i o n t o t h e s e some p a p -i l l a r s p i n e s w e r e s e e n a t t h e l e v e l o f t h e v e n t r a l s u c k e r . I n t h i s r e g i o n two were s e e n o n t h e l e f t s i d e o f t h e c e r -c a r i a a n d one i n t h e c o r r e s p o n d i n g p o s i t i o n o n t h e o p p o s i t e s i d e o f t h e b o d y . I t i s p r o b a b l e t h a t t h e s e more p o s t e r i o r p a p i l l a r s p i n e s a r e a r r a n g e d b i l a t e r a l l y s y m m e t r i c a l l y a n d t h a t some o f t h e m w e r e n o t s e e n a t t h e t i m e o f o b s e r v a t i o n . T h e p a p i l l a e l o c a t e d i n t h e r e g i o n o f t h e v e n t r a l s u c k e r a r e much l e s s d i s t i n c t t h a n t h o s e n e a r t h e o r a l s u c k e r . I n some i n s t a n c e s t h e m i n u t e h a i r l o c a t e d o n t h e p a p i l l a n e a r -e s t t h e e y e s p o t a n d o n t h e two p a p i l l a e n e a r t h e j u n c t i o n o f t h e o r a l o r g a n a n d l a t e r a l c u t i c l e w e r e v e r y l o n g a n d d i s t i n c t . O f e s p e c i a l i m p o r t a n c e i s t h e f a c t t h a t t h e g r o u p s o f p a p i l l a r s p i n e s a r e n o t a l l i n t h e same p l a n e o f f o c u s . Two h e a v i l y p i g m e n t e d e y e s p o t s a r e l o c a t e d a p p r o x -i m a t e l y one t h i r d o f t h e d i s t a n c e f r o m t h e o r a l t o t h e v e n t r a l s u c k e r . T h e e y e s p o t s p o s s e s s a l e n s w h i c h i s d i r - ^ e c t e d l a t e r a d . T h e b o d y c o n t a i n s f i v e p a i r s o f p e n e t r a t i o n g l a n d s . T h e two a n t e r i o r p a i r a r e more g r a n u l a r i n a p p e a r a n c e t h a n t h o s e f a r t h e r p o s t e r i o r . T h e y a r e a r r a n g e d w i t h t h e f i r s t p a i r a n t e r i o r t o t h e v e n t r a l s u c k e r a n d t h e s e c o n d p a i r 26. postero-lateral to i t . Farther posteriorly the remaining three p a i r of glands are arranged somewhat l i n e a r l y on each side of the body. The ducts of the penetration glands were seen i n cross-section at a flexure within the oral sucker and here f i v e individual ducts were distinguished. No pap-i l l a e were seen at the point of exit of the ducts through the anterior c u t i c l e , although these may have been present. An oesophagus beginning within the oral sucker at a point somewhat posterior to the anterior end runs back between the anterior p a i r of penetration glands, bifurcat-ing behind the pair of eyespots. The caeca were obscured by the penetration glands and t h e i r termination was not observed. The excretory system consists of s i x pairs of flame c e l l s within the body and one p a i r i n the proximal portion of the tail-stem. A l l lead into a system of c o l -l e c t i n g tubules. On both sides of the body,there i s one flame c e l l on each side of the eyespot and one other be-tween the eyespot and the bifurcation of the main excret-ory c o l l e c t i n g tubule. Three flame c e l l s are located post-erior to the above bifurcation on each side of the body. Thus the flame c e l l pattern of t h i s cercaria i s 2(3+/3+l/). One departure from the above pattern of t h i s cercaria was noted. In t h i s instance the flame c e l l located immediately posterior to the eyespot i n other cercariae was seen to be adjacent to flame c e l l number one, and i t s junction with the anterior tubule was also anterior to the eyespot. This situ a t i o n existed on one side of the cercaria only. No reason can be given for t h i s departure from the apparently normal condition and i t must therefore be considered an anomaly. 27. Najim(l95l) observed similar anomalies i n the excretory-system of the cercaria of Gigantobilharzia huronensis. The main c o l l e c t i n g tubule runs into an excretory bladder p o s t e r i o r l y . Two c i l i a t e d patches are located near the b i -furcation of the main c o l l e c t i n g tubule on each side of the body. One of these i s situated i n the main c o l l e c t i n g tubule near the point of bifurcation. The position of the other patch i s not entirely certain. It i s located either i n the proximal portion of the posterior l a t e r a l excretory tubule or i n the main c o l l e c t i n g tubule. An excretory tube runs from the bladder medially down the length of the t a i l -stem and bifurcates. One branch passes through each furca, opening terminally through an excretory p a p i l l a . No Island of Gort could be seen near the excretory bladder. The blad-der was very obscure i n outline and could not be observed c l e a r l y . Behavior: The cercaria of T.adamsi i s p o s i t i v e l y phototactic and the cercariae c o l l e c t quite rapidly i n the side-arm of the "concentrator". Some of them attach by the ventral suc-ker to the side of the glass on the l i g h t side. In t h i s pos-i t i o n they form a U shape. Others remain free swimming on th i s side. The'cercariae do not congregate at the surface f i l m but are usually found i n a l l parts of a v i a l contain-ing them. When resting the furcae are usually held together. Under a cover-glass the cercariae are rarely observed l y i n g i n a dorso-ventral position due to the degree of protrusion of the ventral sucker. They sometimes hitch along under a cover-glass by alternate attachment of the ventral and oral suckers. 28. Dermatitis-Producing A b i l i t y ; The cercaria of T.adamsi i s a dermatitis-producer, as determined by experiment. This section i s discussed more f u l l y under "Schistosome dermatitis Experiments". Snail Host and Percent Infection; The cercaria emerged from a s n a i l i d e n t i f i e d as Physa c.f.coniformis. This s n a i l was collected from Area B, C16, on August 3, 1953, and was the only s n a i l collected from which the cercariae were obtained. On the above date 25 Physa were taken. Since the cercariae were obtained only t h i s once the percent i n f e c t i o n must be based only upon th i s c o l l e c t i o n . The i n f e c t i o n percentage can be considered only during the period of time at which the cercariae are emerg-i n g — s n a i l s infected were determined only by c e r c a r i a l emerg-ence. Since, i n the case of the cercaria of T.adamsi, the only period of emergence which we can be sure of i s the date which the infected s n a i l was collected,-the percent i n f e c t i o n must be calculated upon the basis of the.number of snails collected at that time. The p o s s i b i l i t y exists that the cercaria was emerging during other v i s i t s to t h i s area and"was missed i n the c o l l e c t i o n s . This cannot be known for certain, however. The percent i n f e c t i o n , since one of the 25 Physa gave off cercariae, i s 4%. Comparison With Known Forms; With the increased recognition of Schistosome dermatitis i n the l a s t few decades i t i s doubtful i f a Schistosome cercaria has been described without an i n v e s t i -2 9 . gation into i t s a b i l i t y to produce a dermatitis. It becomes necessary then to compare the cercaria of T.adamsi with other dermatitis-producers for the p o s s i b i l i t y of synonym-i t y . Further, t h i s cercaria need only be compared with others possessing the same flame c e l l p a t t e r n — t h a t i s , s i x pairs of flame c e l l s i n the body and one p a i r i n the tail-stem. Cort(1950) states that the chief reason f o r separ-ation of Cercaria dermolestes from C.stagnicolae i s that the s n a i l host of the former i s Stagnicola p a l u s t r i s , while the host of C.stagnicolae i s S.emarginata. This i s a separ-ation based on differences between hosts of the same genus Stagnicola. A high degree of host s p e c i f i c i t y i s usually found i n the Schistosomes. It i s reasonable therefore, to conclude that cercariae emerging from snails of d i f f e r e n t families need not be compared c r i t i c a l l y for the p o s s i b i l i t y of synonymity. All.dermatitis-producers known to date para-s i t i z e snails of one family only. On t h i s basis comparison w i l l be made between the cercaria of T.adamsi and other dermatitis-producers which pa r a s i t i z e snails of the family Physidae. Cercaria oregonensis MacFarlane and Macy(1946) i s a dermatitis-producer which i s found i n physa sp. In the past a certain amount of doubt has existed as to whether C.oregonensis i s actually d i s t i n c t enough from other cer-cariae of the " o c e l l a t a group" to be considered a separate species. However, Macy and Moore(1953) claim to have esta-blished the adult of t h i s cercaria and they give data which seems to support the view that the cercaria i s a separate species. The measurements of the cercaria of T.adamsi do not come close to the measurements of C.oregonensis. The 3 0 . two a n t e r i o r p a i r s o f p e n e t r a t i o n g l a n d s o f t h e l a t t e r a r e l o c a t e d w e l l i n f r o n t o f t h e v e n t r a l s u c k e r , w h e r e a s t h e s e g l a n d s i n o u r c e r c a r i a a r e d i s t r i b u t e d a b o u t t h e v e n t r a l s u c k e r . D i f f e r e n c e s i n t h e p o s i t i o n s o f t h e e x c r e t o r y s t r u c -t u r e s o f t h e two c e r c a r i a e e x i s t , t h e mos t a n t e r i o r f l a m e c e l l o f C . o r e g o n e n s i s l y i n g m e d i o - p o s t e r i o r l y t o t h e e y e -s p o t . F u r t h e r , t h e b i f u r c a t i o n o f t h e m a i n c o l l e c t i n g t u b -u l e i n t h e l a t t e r d o e s n o t c o i n c i d e w i t h t h a t o f o u r c e r c a r -i a . T h e c e r c a r i a o f T r i c h o b i l h a r z i a c a m e r o n i W u ( l 9 5 3 ) v e r y c l o s e l y r e s e m b l e s t h a t o f T . a d a m s i . H o w e v e r , a s i g n i f -i c a n t d i f f e r e n c e e x i s t s b e t w e e n t h e two f o r m s i n t h e r a t i o o f t h e body l e n g t h t o t h e t a i l - s t e m l e n g t h . I n t h e f o r m e r t h i s r a t i o i s . 8 6 , w h i l e i n t h e G u l t u s L a k e c e r c a r i a t h e r a t i o o f t h e b o d y l e n g t h t o t h e t a i l - s t e m l e n g t h i s . 6 7 . T h e mos t o b v i o u s p o i n t s o f d i f f e r e n c e b e t w e e n t h e s e two s p e c i e s a r e s e e n u p o n c o m p a r i s o n o f t h e a d u l t s . C e r c a r i a p h y s e l l a e i s v e r y s i m i l a r t o t h e c e r c a r i a o f T . a d a m s i m o r p h o l o g i c a l l y a n d t h e s n a i l h o s t s b e l o n g t o t h e same f a m i l y , i . e . t h e P h y s i d a e . D i f f e r e n c e s i n t h e m e a s -u r e m e n t s o f t h e s e two f o r m s e x i s t a n d t h e s e a r e g i v e n i n T a b l e 1 . I t i s e a s i e r t o c o m p a r e t h e a d u l t s o f t h e s e two s p e c i e s s i n c e t h e c e r c a r i a e a r e so s i m i l a r i n e v e r y r e s p e c t . C o m p a r i s o n s o f t h e c e r c a r i a o f T . a d a m s i w i t h o t h e r f o r m s h a s n o t b e e n c o n s i d e r e d o n t h e b a s i s o f t h e p o s s e s s i o n by t h i s c e r c a r i a o f p a p i l l a r s p i n a t i o n . The p o s s i b i l i t y d o e s e x i s t t h a t t h i s t y p e o f s p i n a t i o n h a s b e e n o v e r l o o k e d by o t h e r w o r k e r s " i n t h e i r o b s e r v a t i o n s o f t h e c e r c a r i a e now k n o w n . 31 T A B L E 1 C o m p a r i s o n o f M e a s u r e m e n t s o f t h e C e r c a r i a o f T . a d a m s i a n d C e r c a r i a p h y s e l l a e . D i m e n s i o n C e r c a r i a o f T . a d a m s i C . p h y s e l l a e * B o d y l e n g t h . 2 3 0 1 . 0 0 6 9 mm . 2 6 5 . 0 0 8 4 mm B o d y w i d t h . 0 8 0 2 . 0 0 1 4 mm . 0 6 0 . 0 0 4 6 mm T . S . l e n g t h . 3 4 1 3 . 0 0 2 3 mm . 3 7 4 . 0 1 0 6 mm T . S . w i d t h . 0 4 3 8 . 0 0 0 8 2 mm . 0 4 0 ± . 0 0 3 6 mm P u r e . l e n g t h . 2 0 0 7 . 0 0 5 4 mm . 1 9 6 . 0 0 7 8 mm O r a l s u c . d i a . . 0 5 1 5 . 0 0 0 7 1 mm . 0 3 9 . 0 0 2 0 mm V e n t . s u e . d i a . . 0 3 7 2 . 0 0 0 6 2 mm . 0 2 9 . 0 0 2 4 mm * T h e m e a s u r e m e n t s o f C . p h y s e l l a e w e r e t a k e n f r o m t h e d e s c r i p t i o n by T a l b o t ( 1 9 3 6 ) . 32 OVUM AND M I R A C I D I U M S i n c e worm e g g s w e r e n e v e r f o u n d i n f a e c a l e x a m -i n a t i o n s o f t h e d u c k i t i s n o t p o s s i b l e a t t h i s t i m e t o d e s c r i b e d t h e m o r p h o l o g y o f t h e ovum o r m i r a c i d i u m l a r v a o f T . a d a m s i . T h e l a c k o f eggs i n t h e f a e c e s o f t h e d u c k was i n a l l p r o b a b i l i t y due t o t h e worm b e i n g t o o i m m a t u r e a t t h a t p a r t i c u l a r t i m e . On t h e b a s i s o f t h i s r e a s o n i n g t h e c o m p a n i o n d u c k , s u b j e c t e d t o t h e same c e r c a r i a e a t t h e same t i m e , was a l l o w e d t o l i v e f o r a n a d d i t i o n a l 30 d a y s w i t h t h e hope t h a t a n y worms w h i c h m i g h t be p r e s e n t w i t h i n i t w o u l d m a t u r e . H o w e v e r , a s p r e v i o u s l y m e n t i o n e d , t h i s d u c k was l a t e r f o u n d t o be u n i n f e c t e d . SPOROCYSTS ( P l a t e I V ) On t h e m o r n i n g o f A u g u s t 17 t h e s n a i l " i n f e c t e d w i t h t h e c e r c a r i a o f T . a d a m s i was f o u n d t o be d e a d . I t was d i s s e c t e d i m m e d i a t e l y . T h e s p o r o c y s t s w i t h i n t h e s n a i l t i s s u e h a d n o t y e t r e a c h e d a s t a t e o f d i s i n t e g r a t i o n w h i c h w o u l d r e n d e r t h e m u s e l e s s f o r s t u d y . D i s s e c t i o n r e v e a l e d a f a i r l y h e a v y i n f e s t a t i o n o f s p o r o c y s t s w i t h i n t h e d i g e s t i v e g l a n d . I t was i m p o s s i b l e t o u n t a n g l e t h e s p o r o c y s t s s u f f i c i e n t l y t o a l l o w a n a p p r e c -i a t i o n o f t h e i r l e n g t h a n d t o d r a w t h e m w i t h a n y d e g r e e o f a c c u r a c y . A p a r t o f t h e t a n g l e was t h e r e f o r e s e p a r a t e d a n d t h i s was p h o t o g r a p h e d t o r e c o r d some o f t h e d e t a i l s o f t h e s p o r o c y s t s ' m a c r o s c o p i c m o r p h o l o g y . I t was p o s s i b l e t o m e a s u r e t h e w i d t h v a r i a t i o n s 33. of these sporocysts without having to untangle them. The measurements obtained are given i n Table 2. The width of the sporocysts varied from a minimum of .035 mm to a max-imum of .175 mm. The large degree of v a r i a t i o n i s due to the fact that the sporocyst consists for the most part of an alternation of f a i r l y large bulges and extremely narrow portions along i t s length. Since the sporocysts had been dead for a short time p r i o r to the dissection of the s n a i l the developing cercariae within them could not be seen cl e a r l y i n outline. It i s reasonable to assume that the bulges along the sporocyst's length contained groups of the developing cercariae, the narrow portions being too small for these cercariae to be present within. TABLE 2 Measurements of Width of T.adamsi Sporocysts. Measurements of Width (mm). Range .063 .056 .154 .035-.175 mm .140 ,.135 .140 Average .175 .133 .168 .035 .108 mm .035 .147 .119 ADULT FEMALE WORM (Plate 11) 3 4 . . The adult of Tr i c h o b i l h a r z i a adamsi was i n i t i a l l y suspected as being a parasite of birds, on the basis of the flame c e l l pattern of the cercaria. The l a t t e r posses-ses s i x pairs of flame c e l l s i n the body, a condition exist ing i n most other dermatitis-producing cercariae found to mature i n birds. Possessing the cercaria of T.adamsi, ex-perimental attempts were made to raise adult worms i n two Pekin ducklings (Anser domesticus) aged approximately one month. One was subjected to the cercariae on August 5 and the other on the following day. The birds were made to stand i n a jar containing 1.5 cms. of water with approximat l y one to two dozen cercariae, for a period of 15 to 20 min Bites. During t h i s time the ducklings frequently drank the water and splashed about considerably, thus increasing the chance of th e i r becoming infected. The f i r s t duck was a a c r i f i c e d on September 16, 42 days afte r exposure to the cercariae. Examination of the viscera revealed one immature adult female Schistosome i n the l i v e r . The worm was considered immature since no.eggs were present within the uterus and previous faecal examin-ations had not revealed ova. Since the one wOrm found i n the f i r s t duck was thought to be immature i t was considered advisable to allow the remaining duck, subjected to the same cercariae at approximately the same time, to l i v e for a longer period. This would give any worms which might be present a chance to mature. The second duck was s a c r i f i c e d on October 7, ex-actly 70 days from the time of exposure to the cercariae. 3 5 . Examination of t h i s duck f a i l e d to reveal any worms i n the viscera. The worm found i n the f i r s t duck was studied while l i v i n g . It was then examined afte r i t had been k i l l e d with formalin and f i n a l l y from a permanent mount. For mounting i t was stained with Acetic-alum-carmine and counter-stained with Light Green. Behavior: The worm was discovered i n the l i v e r residue one-half to three-quarters of an hour a f t e r the l i v e r had been removed from the duck. At this time the worm was quite ac-t i v e , though the duck had been dead f o r approximately one hour. It did not "hitch along" i n the dish but the anterior end performed apparently aimless twisting motions. When brought beneath a cover-glass on a s l i d e the worm did not at any time stretch out into a straight l i n e . This made measurements of the body length very d i f f i c u l t to obtain. External Morphology; The entire body i s d i s t i n c t l y flattened, especially the posterior h a l f . The posterior end of the body i s truncate and consists of three lobes, two l a t e r a l and the other mak-ing up the posterior termination of the body. The worm pos-sesses both an oral sucker and a ventral sucker, the l a t t e r of which i s at f i r s t seen only with d i f f i c u l t y . Coarse spines cover the anterior portion of the body. These are arranged i n l i n e s which run transversely 3 6 . over the cuticular surface. The anterior coarse spines merge more posteriorly into spines which are les s obvious at about the l e v e l of the posterior edge of the ventral sucker. The spination i s present on the entire body sur-face and i s more easily seen near the posterior region of the body than along the middle. Minute p a p i l l a r spines, seen only " i n vivo", are located on the l a t e r a l c u t i c l e near the extreme anterior end of the worm. A description of these spines i s given more f u l l y under a separate heading. Three b i l a t e r a l pairs were seen, i n addition to one spine further posterior than the others which probably possessed an unseen mate on the opposite side. On each side a spine i s located approximate-l y mid-way between the most anterior end of the worm and the junction of the oral sucker with the l a t e r a l c u t i c l e ; two are located f a i r l y close together immediately posterior to the above junction. One spine was seen on the right side a s l i g h t distance posterior to the previous p a i r . This spine i s the one which probably was duplicated on the opposite side. The description of the p a p i l l a r spination reveals that the r e l a t i v e positions of these spines i n the adult i s i d e n t i c a l with the r e l a t i v e positions of the anterior groups of spines noted on the cercaria. The ventral sucker has an almost globular appear-ance and i t i s probable that the organ i s used not as a sucker but as a means of eroding the surrounding tissue f or attachment. Very long r a d i a l l y arranged spines are present on the convex surface of the organ. 37. I n t e r n a l S t r u c t u r e : A n a r r o w , somewhat t w i s t e d o e s o p h a g u s l e a d s f r o m t h e o r a l s u c k e r p o s t e r i o r l y t o a l e v e l s l i g h t l y a n t e r i o r t o t h e v e n t r a l s u c k e r . A t t h i s p o i n t t h e o e s o p h a g u s b i f u r -c a t e s f o r m i n g two p o u c h - l i k e t u b e s l a t e r a l l y a n d i m m e d i a t e l y a n t e r i o r t o t h e v e n t r a l s u C k e r . T h e two t u b e s , o r i n t e s t -i n a l c a e c a , t h e n a p p r o a c h t h e m i d - l i n e a g a i n a n d d i s a p p e a r i n t h e r e g i o n o f t h e v e n t r a l s u c k e r . T h e p o s t e r i o r p o r t i o n o f t h e o e s o p h a g u s a n d e s p e c i a l l y t h e two l a t e r a l p o u c h e s o f t h e c a e c a c o n t a i n m a s s e s o f y e l l o w i s h g r a n u l e s w h i c h a r e p r o b a b l y t h e r e m a i n s o f i n g e s t e d e r y t h r o c y t e s . B e t w e e n t h e v e n t r a l s u c k e r a n d t h e p o s t e r i o r e n d o f t h e o v a r y t h e i n t e s t -i n a l t r a c t i s e i t h e r c o m p l e t e l y i n v i s i b l e o r e x t r e m e l y i n d i s -t i n c t . B e t w e e n t h e s u c k e r a n d t h e a n t e r i o r e n d o f t h e o v a r y t h e r e a p p e a r s a t h i c k t w i s t e d t u b e w h i c h i s e i t h e r d o u b l e o r p o s s e s s i n g a v e r y l a r g e l u m e n . I n t h e r e g i o n o f t h e o v a r y t h e c o u r s e o f t h e i n t e s t i n a l t r a c t i s i n d o u b t . P o s t e r i o r t o t h e o v a r y t h e i n t e s t i n e c o n t i n u e s i t s c o u r s e a s a s i n g l e u n b r a n c h e d t u b e t o a p o i n t n e a r t h e f l d & e n e d p o s t e r i o r e n d . T h e i n t e s t i n e u n d u l a t e s i n a h o r i z o n t a l p l a n e b e t w e e n t h e o v a r y a n d t h e p o s t e r i o r e n d o f t h e b o d y . I t c o u l d n o t be d e t e r m i n e d w i t h a n y d e g r e e o f c e r t a i n t y w h e t h e r t h e l a t e r a l c a e c a b i f u r c a t e d a n t e r i o r t o t h e v e n t r a l s u c k e r a g a i n u n i t e i n t h e i m m e d i a t e v i c i n i t y o f t h e v e n t r a l s u c k e r , o r w h e t h e r t h i s u n i o n o c c u r s f u r t h e r p o s t e r i o r l y i n t h e r e g i o n o f t h e o v a r y . T h i s l a t t e r c o n d i t i o n e x i s t s i n t h e c l o s e l y s i m i l a r f o r m s , i . e . T . o c e l l a t a , T . s t a g n i c o l a e a n d T . p h y s e l l a e ( M c M u i -l e n a n d B e a v e r , 1 9 4 5 ) . H o w e v e r , i n t h e a r e a b e t w e e n t h e v e n -t r a l s u c k e r a n d t h e o v a r y t h e t h i c k e n e d t u b e s e e n d o e s n o t a p p e a r o b v i o u s l y d o u b l e . F u r t h e r , t h e manne r i n w h i c h t h e two l a t e r a l p o u c h - l i k e e n l a r g e m e n t s a n t e r i o r t o t h e v e n t r a l s u c k e r a p p r o a c h t h e m i d - l i n e seems t o s u g g e s t i n i t s v e r y 38. a b r u p t n e s s a f u s i o n o f t h e s e t u b e s i n t h e i m m e d i a t e v i c i n -i t y o f t h e v e n t r a l s u c k e r . The q u e s t i o n mus t f o r t h e moment r e m a i n a n o p e n o n e u n t i l f u r t h e r e v i d e n c e i s a c c u m u l a t e d c o n c e r n i n g t h i s p o i n t . T h e f a i r l y c o n s p i c u o u s o v a r y i s l o c a t e d w i t h i t s a n t e r i o r e n d .175 mm p o s t e r i o r t o t h e edge o f t h e v e n t r a l s u c k e r . T h e o v a r y i s s l i g h t l y c o n v o l u t e d p o s s e s s i n g f o u r a n d one h a l f l o o p s a l o n g i t s l e n g t h . No t r a c e c o u l d be s e e n o f t h e c o n t i n u a t i o n o f t h e o v a r y i n t o . a n o v i d u c t , n o r o f a s e m i n a l r e c e p t i c a l b e h i n d t h e o v a r y . I n f a c t , no o t h e r t r a c e o f t h e g e n i t a l t r a c t c o u l d be d i s c e r n e d . I t i s p r o b a b l e h o w e v e r , t h a t t h e o v i d u c t c o n t i n u e s somewhat a n t e r i o r t o i t s p o i n t o f d e p a r t u r e f r o m t h e o v a r y . A v i t e l l i n e d u c t i s s e e n s u p e r i m p o s e d u p o n t h e s u r -f a c e o f t h e o v a r y a n d e x t e n d i n g f u r t h e r p o s t e r i o r l y a l o n g t h e i n t e s t i n a l t r a c t . T h e a n t e r i o r a n d p o s t e r i o r t e r m i n a -t i o n s o f t h i s d u c t w e r e q u i t e i n d i s t i n c t . N u m e r o u s v i t e l l a r i a a r e s c a t t e r e d f u r t h e r p o s t e r i o r l y o n e i t h e r s i d e o f t h e i n -t e s t i n a l t r a c t a n d t h e s e c o n t i n u e t o a p o i n t s l i g h t l y a n -t e r i o r t o t h e b e g i n n i n g o f t h e p o s t e r i o r l o b a t i o n o f t h e b o d y . A p a r t i c u l a r l y o u t s t a n d i n g c h a r a c t e r i s t i c o f t h i s worm i s t h e p o s s e s s i o n o f c l u s t e r s o f y e l l o w , g l i s t e n i n g g l o b u l e s i n t h e a n t e r i o r p o r t i o n o f t h e b o d y ( a n t e r i o r t o t h e o v a r y ) . T h e s e g l o b u l e s a p p e a r t o be v e r y c l o s e b e n e a t h t h e s u r f a c e o f t h e b o d y c u t i c l e a n d a r e mos t c o n c e n t r a t e d i n t h e r e g i o n a n t e r i o r t o t h e v e n t r a l s u c k e r . T h e g l o b u l e s a r e v e r y s i m i l a r i n a p p e a r a n c e t o t h e m i n u t e b o d i e s w i t h i n t h e i n t e s t i n a l c a e c a a n d t h e y p o s s e s s t h e same y e l l o w h u e . 39. However, they seem to tae more regular i n t h e i r outline than are the l a t t e r . Another feature of t h i s worm, which does not ap-pear to have been described for any other similar form, i s the occurance " i n vivo" seemingly on the surface of the ven-t r a l c u t i c l e near the posterior of the body, of longitud-i n a l s t r i a t i o n s which give the appearance of p a r a l l e l ducts. These fine l i n e s are extremely d i f f i c u l t to observe. Eleven of them were seen as i l l u s t r a t e d i n Plate 11. Comparison of T.adamsi With Known Forms; Comparison with other forms indicates that the Schistosome now being dealt with i s a member of the genus Trich o b i l h a r z i a , as redescribed by McMullen and Beaver i n 1945. A more detailed comparison between th i s and other members of the Schistosomatidae i s given under "Taxonomic Discussion". The adult Schistosome resembling most closely T r i c h o b i l h a r z i a adamsi i s T.physellae. In Table 3 the meas-urements of T.adamsi are compared with those of T.physellae. Since the measurements of T.adamsi were made under different conditions a seperate column i s provided stating the condi-tions under which each measurement was obtained. T.physellae i s similar to T.adamsi on the basis of morphology and host relationships. Both of these forms un-dergo developement i n a Physa i n the intermediate stage of the l i f e - c y c l e . A l l members of the "oc e l l a t a group" for which the adult has been described undergo developement i n 40. Lymnaeid snails excepting T.physellae. Prom Table 3 i t can be seen that T.adamsi i s con-siderably wider than T.physellae especially i n the region near the ventral sucker. This difference i s s i g n i f i c a n t i n view of the probable immaturity of the one T.adamsi meas-ured. The greater.width of T.adamsi i s reflected i n the width of the oral sucker of this form as compared with the sucker width of T.physellae. Due to the degree of flexure of the body of the Gultus Lake form the body length had to be measured by a summation of the lengths of the flexes. This method i s inaccurate but i t w i l l give a value within plus or minus ten calibrations, or ± .19 mm at the magni-f i c a t i o n used f o r this observation. The body thickness of I.physellae i s between one-half and two-thirds of the width. Measurements of the permanent mount of T.adamsi indicate that the thickness i s about two-fifths of the width immed-i a t e l y posterior to the ventral sucker. It i s probable that the worm was s l i g h t l y compressed under the cover-glass how-ever, e f f e c t i n g a greater degree of f l a t t e n i n g . Nevertheless, the difference i n thickness between these two forms i s s i g -n i f i c a n t . McMullen and Beaver(l945) indicated that i n some cases T.physellae appeared to possess "extremely f i n e spines" which, were especially obvious near the middle of the body of the males of t h i s species. The body spines of T.adamsi are readily seen and are especially obvious anterior to the ventral sucker. Further, T.adamsi possesses the p a p i l l a r spination which i s unique and has not been described on any other adult dermatitis-producer. No spherical yellow glob-ules are described as occurring i n T.physellae. The above differences would seem to eliminate the TABLE 3 Comparison of Measurements of T.adamsi w i t h T . p h y s e l l a e Dimension C o n d i t i o n Under Which Measurment Made of T.adamsi Measurments of T.adamsi Corresponeding Measurment f o r T . p h y s e l l a e Body Widths -across v . s . - f u r t h e r p o s t . i n v i v o .105 mm .093 mm .04-.08 mm Body Length \ % f o r m a l i n 3 . 6 l mm up to 4.4 mm V e n t r a l Sucker: -width l e n g t h 15% f o r m a l i n .064 mm .026 mm .024-.032 mm r e t r a c t e d , up to .04 mm p r o t r u d i n g . O r a l Sucker: -width - l e n g t h 15% f o r m a l i n .036 mm .039 mm .024-.028 mm .024-.044 mm C u t i c l e ( L a t . ) 15^ f o r m a l i n .004 mm Vent.Sue.-Oral permanent mount .111 mm . 2 - . 3 mm extended, .14 c o n t r a c t e d wsmrm. Vent.Sue.to Oesoph.Bifurea. permanent mount .026 mm .024-.060 mm Ovary to hack of V e n t r a l Sucker permanent mount .175 m m .1-.3 mm 42. p o s s i b i l i t y of synonymity between these two forms. The cercariae of T.physellae d i f f e r from those of T.adamsi, p r i n c i p a l l y i n t h e i r measurements. This aspect was discus-sed under the description of the cercaria of T.adamsi. Recently, another species of T r i c h o b i l h a r z i a was added to the l i s t of the three previously known dermatitis-producing members of t h i s genus. This was T r i c h o b i l h a r z i a  cameroni Wu(l953). This worm i s described as being'from .052 to .059 mm i n width i n the region of the ovary. The measurement i s to be contrasted with that of T.adamsi which, as indicated i n Table 3, measured .0933 mm " i n vivo". Wu described the i n t e s t i n a l caeca of T.cameroni as reuniting "anterior to the reproductive organs". Although i t i s not known .for certain, t h i s situation seems also to exist i n T.adamsi and the caeca may actually unite i n the region of the ventral sucker. The ventral sucker of T.cameroni i s des-cribed as quite prominent. The organ i n T.adamsi i s not pro-minent and t h i s region of the worm must be scrutinized f a i r -l y c a r e f u l l y before the sucker can be seen. Another point of d i f f e r e n t i a t i o n between the two worms l i e s i n the fact that the former possesses no body spination. T.adamsi possesses body spination and i n addition the p a p i l l a r spines on the anterior region of the body. PLATE 1 1 Immature adult female of T r i c h o b i l h a r z i a adamsi. — T h e drawing was made f r e e - h a n d — PLATE 11 PLATE 111 Eig.l-Cercaria of T.adamsi with body twisted to side to show de t a i l s of excretory system. Ei g . 2 - C e r c a r i a of T.adamsi, dorso-ventral view. X de-notes a p a p i l l a r spine. —Drawings made free-hand— PIG. 1 FIG. 2 P L A T E 111 PLATE IV Photomicrographs of Trichobilharzia adamsi sporocysts. . —The pointers should be ignored— F i g s . l and 2- X 40. Pig. 3 - X 100. P L A T E I V 43. CERCARIA 1 6 A Cercaria 16A i s mentioned b r i e f l y at t h i s time since i t possesses the p a p i l l a r spination described as char-a c t e r i s t i c of the other cercariae i n t h i s work. Of further interest i s the fact that this cercaria occurred i n a double i n f e c t i o n . On September 4 Cercaria 16A was discovered emerging from one of the s n a i l s , Lymnaea emarginata, i n the labora-tory. The s n a i l had been collected from Area B (Plate 3Cj on August 29. The l a r v a appeared to be very similar to the cerca r i a of T r i c h o b i l h a r z i a adamsi on the basis of morphol-ogy, especially i n the arrangement of the organ systems. So marked was t h i s resemblance that i n i t i a l l y t h i s cercaria, now designated as Cercaria 16A, was considered as being syn-onymous with the other form. Measurements revealed that C.16A possessed a s l i g h t l y longer tail-stem than that of the other cercaria and this coupled with the fact that the s n a i l host was of a different family than that of the host of the other form le d to the conclusion that the cercaria was pro-bably a different type. Further, the cercaria did not attach as readily to glass as did the cercaria of T.adamsi. Since Cercaria 16A was at f i r s t believed to be syn-onymous with the cercaria of T.adamsi no i n f e c t i o n experi-ments were carried out with this c e r c a r i a . The s n a i l host was dissected before i t was recognized as constituting a separate species. Measurements were made of a few cercariae which had been fixed i n 15$ hot formalin. This was done i n order to 44. effect a rough comparison with those measurements obtained for the cercaria of T.adamsi. Comparison of these measure-ments i s given i n Table 4. The number i n brackets following the measurements of Cercaria 16A indicates the number of cercariae measured. TABLE 4 Measurements of Cercaria 16A and the C.of T.adamsi Dimension Cercaria 16A C. of T.adamsi Body length .273 mm (3) .230 mm Body width .069 mm (2) .080 mm T.S.length .44 6 mm (5) .341 mm T.S.width .042 mm (4) .044 mm Oral suc.wid. .051 mm (4) .052 mm Furcal length .206 mm (5) .201 mm Although the number of Cercaria 16A measured i s not s u f f i c i e n t l y great for an adequate s p e c i f i c diagnosis of this cercaria the average measurements given above w i l l serve for comparison. It can be. seen from the table that the tail-stem of Cercaria 16A i s appreciably longer than that of the other cercaria. The other measurements given coincide quite closely and serve to i l l u s t r a t e to some extent the degree of s i m i l a r i t y of these two cercariae. s Considering the organ systems, the two cercariae d i f f e r to the greatest extent i n the .degree of flexure of the main c o l l e c t i n g tubules near the point of bifurcation l a t e r a l l y . In the cercaria of T.adamsi th i s flexure i s s l i g h t l y looped (Plate 111) whereas the flexure of Cercaria  16A i s much more marked and the tubule i n this region i s somewhat convoluted. 4 5 . In a l l other respects the two cercariae are very si m i l a r . P a p i l l a r Spination; Minute p a p i l l a r spines were seen on the anterior region of th i s cercaria and t h e i r p o s i t i o n corresponded with that of the spines on the cercaria of T.adamsi, with two exceptions. On Cercaria 16A immediately posterior to the junction of the oral sucker with the l a t e r a l c u t i c l e two p a p i l l a r spines were seen close together, as on the cercaria of T.adamsi, and i n addition another was seen fur-ther ventrad between these two by focusing upwards s l i g h t l y . These three p a p i l l a r spines formed a tri a n g l e with two of them on the same horizontal plane and with the "apex" point-ing ventrad. In addition to the spine seen s l i g h t l y ventrad to the l a t e r a l plane of focus another was seen on the .dorsal surface of the cercaria immediately posterior to the junc-t i o n of the oral sucker with the dorsal body c u t i c l e . The cercaria was l y i n g on i t s right side when thi s spine was observed. It appears almost impossible to observe such a spine while viewing i t "end on" and therefore the spine was not seen while the cercaria was l y i n g dorso-ventrally. Double Infection; C e r c a r i a 16A was di s c o v e r e d escaping from the s n a i l host along with a S t r i g e i d cercaria. This represented the only case of a double i n f e c t i o n for any of the cercariae described i n th i s work. The two cercariae could be readily d i s t i n g u i s h e d o n t h e b a s i s o f s i z e a n d b e h a v i o r . ' T h e S c h i s t -osome i s c o m p a r a t i v e l y l a r g e a n d s w i m s somewhat l e t h a r g i c a l -l y . When a t r e s t t h e l a t t e r h o l d s t h e f u r c a e a t r i g h t a n g l e s t o e a c h o t h e r a n d s l o w l y d r i f t s d o w n w a r d . I t i s s l i g h t l y p o s i t i v e l y p h o t o t a c t i c b u t d o e s n o t a t t a c h r e a d i l y t o g l a s s . The S t r i g e i d o n t h e o t h e r h a n d was v e r y s m a l l a n d swam q u i t e a c t i v e l y f o r f a i i l y l o n g p e r i o d s o f t i m e . When b o t h o f t h e s e c e r c a r i a e w e r e p l a c e d t o g e t h e r i n t h e " c o n c e n t r a t o r " ( p a g e 1 7 ) t h e S c h i s t o s o m e s a l o n e w e r e f o u n d i n t h e s i d e - a r m , a t t r a c t e d by t h e l i g h t . . T h i s c o n s t i t u t e s a n e x c e l l e n t m e t h o d o f s e p a r a t i n g t h e two c e r c a r i a e , s i n c e t h e w a t e r i n t h e s i d e -a r m may r e a d i l y be d r a w n o f f c o n t a i n i n g t h e S c h i s t o s o m e s . 47. CERCARIA CHILLIWACKENSIS(Plate V) Morphology; This i s an apharyngeal, furcocercous distome cer-c a r i a of the "douthitti group". The following measurements (with the exception of the body width) were made of 25 cercariae f i x e d i n 15$ hot formalin. Since most specimens after f i x a t i o n were bent s l i g h t l y dorso-ventrally i t was d i f f i c u l t to obtain measurements of the body width and only seven such measurements were taken. The Means of the meas-urements are given with t h e i r Standard error; body length .2668 ± .0084 mm; body width (7 specimens).0782 * .0027 mm; tail-stem length .3606 ± .0026 mm; tail-stem width, prox-imal .0436 ± .00041 mm, d i s t a l .0360 * .00071 mm; f u r c a l length .2058 ± .0042 mm; f u r c a l p a p i l l a length .0145 ± .00029 mm; ventral sucker diameter .0350 ± .00041 mm; or a l sucker length .0864 ± .0032 mm. The ration of the body length to the tail-stem len-gth i s approximately the same as that of the cercar i a of T.adamsi. The furcae of Cercaria chilliwackensis are longer than half the length of the tail-stem. Dorso-ventral f i n -folds are present on the quite narrow furcae. > The 'entire body, tail-stem and furcae are covered with minute retrorse spines. Those covering the body are much more prominent on the anterior h a l f . Farther posterior on the body the spines are d i f f i c u l t to see, probably be-cause they are shorter. Spines on the tail-stem and furcae are spaced considerably farther apart and are shorter than those found on the anterior half of the body. Spines are 48. p r e s e n t e n t h e v e n t r a l s u c k e r a n d t h e s e a r e a r r a n g e d r a d -i a l l y . P a p i l l a r s p i n e s a r e p r e s e n t o n t h e c u t i c l e o f t h e b o d y . T h e s e w e r e s e e n o n t h e l a t e r a l c u t i c l e o f t h e c e r c -a r i a a n d t h o s e n e a r t h e a n t e r i o r e n d o f t h e b o d y o c c u p y much t h e same p o s i t i o n a s do t h o s e o n t h e o t h e r c e r c a r i a e d e s -c r i b e d i n t h i s w o r k ( P l a t e V ) . The p a p i l l a r s p i n e s l o c a t e d p o s t e r i o r t o t h e e y e s p o t s o n t h e o t h e r h a n d , a r e a r r a n g e d i n a d i s t i n c t l y d i f f e r e n t p a t t e r n a n d seem t o be more s p r e a d o u t w i t h r e l a t i o n t o one a n o t h e r . On o n e s i d e o f t h e b o d y p a p i l l a r s p i n e s w e r e s e e n w h i c h d i v i d e d t h e s p a c e b e t w e e n t h e e y e s p o t a n d t h e v e n t r a l s u c k e r r o u g h l y i n t o t h i r d s . A n o t h e r was s e e n o n t h i s s i d e a t t h e l e v e l o f t h e v e n t r a l s u c k e r o r s l i g h t l y p o s t e r i o r t o i t s d i a m e t e r . A p a p i l l a w h i c h c o r r e s -p o n d s t o t h i s l a t t e r p o s i t i o n was s e e n o n t h e o p p o s i t e s i d e o f t h e b o d y a n d a n o t h e r was s e e n o n t h e o t h e r s i d e c o r r e s -p o n d i n g t o t h e p a p i l l a i m m e d i a t e l y p o s t e r i o r t o t h e e y e s p o t d e s c r i b e d a b o v e . I t i s p r o b a b l e t h a t t h e p a p i l l a r s p i n a t i o n i s b i l a t e r a l l y s y m m e t r i c a l a n d t h a t a l l t h e s p i n e s o n t h e o t h e r s i d e were n o t s e e n . T h e mos t p r o m i n e n t o f t h e p a p -i l l a r s p i n e s o n C e r c a r i a e h i l l i w a c k e n s i s a r e t h e p a i r l o c a t -e d i m m e d i a t e l y p o s t e r i o r t o t h e j u n c t i o n o f t h e o r a l s u c k e r w i t h t h e l a t e r a l b o d y c u t i c l e . The s p i n e s o f t h i s c e r c a r i a a r e n o t n e c e s s a r i l y a l l i n t h e same p l a n e o f f o c u s . I t i s p e r h a p s o f e s p e c i a l s i g n i f i c a n c e t h a t i n some i n s t a n c e s t h e s m a l l h a i r - l i k e p r o j e c t i o n o n t h e p a p i l l a e was s e e n t o move o r v i b r a t e a n d j u s t p r i o r t o t h e d e a t h p o i n t o f t h e c e r c a r i a t h i s p r o j e c t i o n was o b s e r v e d t o b e n d o v e r a n d d i s i n t e g r a t e . The two e y e s p o t s a r e h e a v i l y p i g m e n t e d a n d e a c h p o s -s e s s e s a " l e n s " w h i c h i s d i r e c t e d l a t e r a d . T h e e y e s p o t s a r e 4 9 . l o c a t e d between the o r a l and v e n t r a l suckers, s l i g h t l y -a n t e r i o r to the raid-way poin t between .these two organs. The body of the c e r c a r i a possesses f i v e p a i r s of p e n e t r a t i o n glands, the a n t e r i o r two p a i r s of which are . somewhat more g r a n u l a r and darker i n appearance than the p o s t e r i o r glands. The f o u r a n t e r i o r glands surround the v e n t r a l sucker, one p a i r being a n t e r i o r to t h i s organ and one p a i r p o s t e r i o r to i t . A nucleus was seen i n each of them. Three p a i r s of s m a l l e r glands l i e f a r t h e r p o s t e r i o r l y . The ducts of the p e n e t r a t i o n glands, which take a somewhat t w i s t e d course to the a n t e r i o r end o f the body, were seen i n c r o s s - s e c t i o n at one of the more a n t e r i o r f l e x -u r e s . The duct bundle was observed to be composed of f i v e separate ducts on each s i d e . The ducts are s l i g h t l y c o n s t r i c -• t e d at the p o i n t where they pass i n t o the o r a l sucker. No p a p i l l a e were observed at the t e r m i n a t i o n o f the ducts on the a n t e r i o r end of the body, but these s t r u c t u r e s may be p r e s e n t . A f a i r l y l ong, t h i n oesophagus was seen beginning w i t h i n the o r a l sucker at a p o i n t somewhat p o s t e r i o r from the t i p of t h i s organ and extending backward between the ducts of the p e n e t r a t i o n g l a n d s . A b i f u r c a t i o n of the oesophagus cou l d not be d i s c e r n e d . The excretory system of C e r c a r i a c h i l l i w a c k e n s i s i s composed of f i v e p a i r s of flame c e l l s i n the body and one p a i r i n the proximal p o r t i o n of the t a i l - s t e m , a l l l e a d -i n g i n t o a s e r i e s of c o l l e c t i n g t u b u l e s . W i t h i n the body three p a i r s of flame c e l l s are l o c a t e d a n t e r i o r to the vent-r a l sucker and two p a i r s are p o s t e r i o r to i t . These l e a d 50. into the anterior lateral and posterior lateral collecting tubules respectively. . The flame ce l l formula is therefore 2(3+/2+l/). On each side of the body the anterior and post-erior lateral collecting tubules join in the region of the ventral sucker to form a main collecting tubule. This runs posteriorly into an excretory bladder located at the junction of the body with the tail-stem. Two patches of. c i l i a are present on each side of the body. One of these is located in the main collecting tubule near the point of bifurcation. The position of the other is not certain. It is located either in the main collecting tubule or in the anterior l a t -eral collecting tubule. The outline of the bladder could not be seen clearly. Prom the bladder a central excretory tub-ule runs medially down the entire length of the tail-stem and bifurcates. Each branch runs through a furca and opens at the t ip through an excretory papi l la . Behavior: ,Cercaria chilliwackensis exhibits a mild response to a l ight stimulus moving in a positive direction. The degree of negative geotaxis is slight and the cercariae are found in a l l regions of the v i a l . However, when the v ia l i s left undisturbed the cercariae usually cluster near the meniscus, the majority remaining free swimming. Under a strong light stimulus in the "concentrator" approximately one quarter of the cercariae attach to the jar on the pos-i t ive side, forming a U shape with the body and tail-stem. Other cercariae drift ing in the water move intermittantly, t a i l f i r s t , and then while resting dri f t slowly downward with the body below the t a i l . If the cercaria is swimming horizontally i t wi l l sink when resting, with the body 5 1 ; s l o w l y p o i n t i n g d o w n w a r d . The c e r c a r i a e do n o t g a t h e r i n c l o u d s a t t h e s u r f a c e . T h e e m e r g e n c e t i m e o f t h e c e r c a r i a i s q u i t e d i f f i -c u l t t o d e t e r m i n e s i n c e a n y c h a n g e o f t h e w a t e r seems t o i n -d u c e more o f t h e c e r c a r i a e t o e m e r g e . As f a r a s c o u l d be d e t e r m i n e d t h e c e r c a r i a e emerge a f t e r 10 a . m . a n d t h e e m e r -g e n c e c o n t i n u e s n u n t i l a p p r o x i m a t e l y . 2 o r 3 p . m . A t 9 . 3 0 a . m . t h e r e a r e v e r y f e w , i f a n y , c e r c a r i a e p r e s e n t i n t h e v i a l . D e r m a t i t i s - P r o d u c i n g A b i l i t i e s ; C e r c a r i a c h i l l i w a c k e n s i s i s a d e r m a t i t i s - p r o d u c e r a s d e t e r m i n e d by e x p e r i m e n t . T h i s c h a r a c t e r i s t i c i s d i s -c u s s e d more f u l l y u n d e r " S c h i s t o s o m e d e r m a t i t i s E x p e r i m e n t s " . L i f e - c y c l e E x p e r i m e n t s ; E i g h t a l b i n o m i c e , two p i g e o n s a g e d a p p r o x i m a t e l y one m o n t h , a n d one d u c k l i n g w e r e e x p o s e d t o C e r c a r i a c h i l l i -w a c k e n s i s i n t h e l a b o r a t o r y . P o u r o f t h e m i c e w e r e e x p o s e d by h o l d i n g t h e m w i t h t h e t a i l s u s p e n d e d w i t h i n a s m a l l v i a l c o n t a i n i n g a f e w c e r c a r i a e i n w a t e r . T h e r e m a i n i n g f o u r w e r e e x p o s e d w i t h t h e " c o n c e n t r a t o r " . One o f t h e p i g e o n s was made t o s t a n d w i t h i t s f e e t i n a c u p o f w a t e r c o n t a i n i n g f r o m 1 0 0 t o 200 c e r c a r i a e . The o t h e r was g i v e n a n i n t r a -p e r i t o n e a l i n j e c t i o n o f 1 .5 m i s . o f w a t e r c o n t a i n i n g f r o m f i f t e e n t o t h i r t y c e r c a r i a e . The d u c k l i n g was e x p o s e d by i m m e r s i n g t h e f e e t i n a c u p o f w a t e r , o n e - q u a r t e r f i l l e d , c o n t a i n i n g up t o two d o z e n c e r c a r i a e . The m i c e w h i c h h a d b e e n e x p o s e d t o t h e c e r c a r i a e m a n u a l l y w e r e s a c r i f i c e d 4 2 43 and 44 days aft e r i n i t i a l exposure. Those mice which had been put into the "concentrator" were s a c r i f i c e d 55 and 59 days after exposure. Of the two pigeons used i n the ex-periments, one died one month afte r exposure of an unknown cause and the other.was s a c r i f i c e d 45 days after exposure. The pigeon which died prematurely was the one which had been given an intraperitoneal i n j e c t i o n and the death of the bird may have been related to the i n j e c t i o n . A l l attempts to infect laboratory animals with Cerc-a r i a chilliwackensis were unsuccessful. The explanation for t h i s may be that so few cercariae were available for the ex-periments. Cercariae used for the experiments by other work-ers i n the past numbered i n the thousands; i n spite of t h i s , the experiments frequently were unsuccessful(Talbot,1936). Sporocysts: The sporocysts from which Cercaria chilliwackensis was emerging were dissected from a s n a i l giving o f f these cercariae. The s n a i l had been dead for approximately one hour. Dissection revealed that the sporocysts were present as a tangled mass. It was found impossible to dissect any one of these structures out intact i n order to measure i t s length. The macroscopic appearance of the sporocysts was re-corded by photographing them (Plate Vl).. Measurements of the widths of the sporocysts were made. Extreme variations i n the widths occurred and the sporocysts appeared very similar to those of T .adamsi. The widths varied from a minimum of .042 mm. to a maximum of .175 mm. The measurements obtained are given i n Table 5. 53. TABLE 5 Measurements of Width of Cercaria chilliwackensis Sporocysts. Measurements of Range Width (mm) .007 .063 .126 .042-.175 mm. .098 .042 .168 Average .070 .168 .114 mm. .070 .105 .168 Snail Host; On July 7, 1953, cercariae which appeared i d e n t i c a l with Cercaria chilliwackensis were found emerging from a s n a i l i d e n t i f i e d as Physa c.f.coniformis. A l l cercariae were used i n experimental i n f e c t i o n attempts and the s n a i l host died before any of them could be preserved for future study. On July 17 another s n a i l , also physa c.f.coniformis, was discovered i n the laboratory to be giving o f f the cerc-ariae described above as Cercaria chilliwackensis. The only means of comparison between the l a t t e r c e r c a r i a and the f o r -mer were drawings of the f i r s t c e rcaria. On this basis, then, the cercariae were compared and considered i d e n t i c a l . The f i r s t s n a i l was collected on July 16, 1953, from Area A. 5 4 . The l a t t e r s n a i l was c o l l e c t e d o n J u l y 1 6 , 1 9 5 3 , f r o m t h e a r e a " S o u t h e n d o f B e a c h " ( P l a t e 3C ) . P e r c e n t I n f e c t i o n s : B e c a u s e C e r c a r i a c h i l l i w a c k e n s i s e m e r g e d f r o m t h e s n a i l s c o l l e c t e d b o t h f r o m A r e a A a n d " S o u t h e n d o f B e a c h " a n d s i n c e t h e s e s n a i l s w e r e c o l l e c t e d a t d i f f e r e n t d a t e s , i t i s n e c e s s a r y t o s e t t h e d a t e l i m i t s u p o n w h i c h t h e p e r c e n t -a g e s a r e b a s e d t o c o i n c i d e w i t h t h e d a t e s o f c o l l e c t i o n . T h e p e r c e n t i n f e c t i o n o f s n a i l s c o l l e c t e d i n t h e two a r e a s i s t h e r e f o r e b a s e d u p o n t h e p e r i o d f r o m J u l y 4 t o J u l y 1 6 . F u r t h e r , t h e p e r c e n t a g e s a r e b a s e d u p o n t h e number o f Physa lS c o l l e c t e d b e c a u s e t h e s e s n a i l s seem t o be t h e o n l y g e n u s i m p l i c a t e d . O n l y one c o l l e c t i o n was made i n t h e a r e a " S o u t h e n d o f B e a c h " d u r i n g t h e p e r i o d f r o m J u l y 4 t o J u l y 1 6 a n d t h e r e f o r e p e r c e n t a g e c a l c u l a t i o n s a r e b a s e d o n t h e number o f P h y s a c o l l e c t e d d u r i n g t h i s one v i s i t . The number o f s n a i l s c o l l e c t e d d u r i n g t h e a b o v e p e r i o d i s g i v e n i n T a b l e 6 . T A B L E 6 Number o f " S n a i l s C o l l e c t e d i n A r e a s A a n d S o u t h e n d o f B e a c h , W i t h D a t e s . A r e a A S o u t h e n d o f B e a c h D a t e C o l l e c t e d Number • D a t e C o l l e c t e d Number J u l y 4 J u l y 16 125 ••' 89 no c o l l e c J u l y 1 6 j t i o n 38 T o t a l s 214 38 A r e a A : C . c h i l l i w a c k e n s i s i n ^ - J x 100= . 4 6 7 % o f P h y s a s 5 5 . S o u t h e n d o f B e a c h ; G . c h i l l i w a c k e n s i s i n 55- x 100 = 2 . 6 3 % o f P h y s a s . 38 T h e p e r c e n t i n f e c t i o n b a s e d o n t h e t o t a l n u m b e r o f s n a i l s ( P h y s a ) c o l l e c t e d f r o m b o t h o f t h e s e a r e a s d u r i n g t h e p e r i o d f r o m J u l y 4 t o J u l y 16 i s e x p r e s s e d a s ; 2 1 4 ^ 3 8 x 100 = . 7 9 4 % o f P h y s a s . C o m p a r i s o n W i t h Known F o r m s ; C e r c a r i a c h i l l i w a c k e n s i s p o s s e s s e s a n e x c r e t o r y s y s t e m w i t h one p a i r o f f l a m e c e l l s l e s s t h a n t h e s e v e n p a i r s c h a r a c t e r i s t i c o f t h e " o c e l l a t a g r o u p " . I t i s t h e r e -f o r e n e c e s s a r y t o c o m p a r e t h i s c e r c a r i a w i t h o t h e r s p o s s -e s s i n g f i v e p a i r s o f b o d y f l a m e c e l l s . I n a d d i t i o n , C . c h i l -l i w a c k e n s i s w i l l be c o m p a r e d w i t h c e r c a r i a e w h i c h a r e k n o w n d e r m a t i t i s - p r o d u c e r s . C e r c a r i a t u c k e r e n s i s M i l l e r ( 1 9 2 7 ) e x h i b i t s t h e g r e a t e s t d e g r e e o f s i m i l a r i t y t o C . c h i l l i w a c k e n s i s m o r p h -o l o g i c a l l y ; C . t u c k e r e n s i s i s somewhat l a r g e r a n d n a r r o w e r t h a n C . c h i l l i w a c k e n s i s . A c o m p a r i s o n o f t h e m e a s u r e m e n t s o f t h e s e two c e r c a r i a e i s g i v e n i n T a b l e 7 . M e a s u r e m e n t s o f C . t u c k e r e n s i s w e r e o b t a i n e d f r o m M i l l e r ( l 9 2 7 ) . P e r h a p s t h e g r e a t e s t p o i n t o f d i f f e r e n c e b e t w e e n C . t u c k e r e n s i s a n d • C . c h i l l i w a c k e n s i s i s t h e f a c t t h a t t h e s n a i l h o s t s o f t h e s e two l a r v a e b e l o n g t o d i f f e r e n t f a m i l i e s . C . t u c k e r e n s i s i s f o u n d i n P i a n o r b i s s p . w h i l e , a s h a s a l r e a d y b e e n s t a t e d , C . c h i l l i w a c k e n s i s i s f o u n d i n P h y s a . 56 TABLE 7 -Comparison of Measurements of C . c h i l l i w a c k e n s i s and C.tuckerensis Dimension C . c h i l l i w a c k e n s i s C.tuckerensis Body leng t h .267 mm .325 mm Body width .078 mm .08 mm T.S.length .361 mm .4 mm T.S.width .044 mm .04 mm Furca le n g t h .206 mm .325 mm Oral suc.len. .086 mm .1 mm C e r c a r i a d o u t h i t t i Cort, as described by P r i c e ( l 9 3 1 ) , resembles C . c h i l l i w a c k e n s i s i n that i t possesses f i v e p a i r s of flame c e l l s i n the body and i s a known de r m a t i t i s - p r o d -ucer. This form however, has no f i n - f o l d s on the furcae and i n a d d i t i o n i t i s found i n Lymnaeidae. C e r c a r i a elongata Brackett has f i v e flame c e l l s on each side of the body. This p a t t e r n d i f f e r s nevertheless from that of C . c h i l l i w a c k e n s i s . C.elongata possesses two flame c e l l s connected to the a n t e r i o r l a t e r a l c o l l e c t i n g tub-ule and three connecting with the p o s t e r i o r tubule. This' c o n d i t i o n i s reversed i n C . c h i l l i w a c k e n s i s . Other d i f f e r -ences between the two c e r c a r i a e are the e x c e p t i o n a l l y long t a i l - s t e m of C.elongata and the occurence of t h i s c e r c a r i a i n the s n a i l Gyraulus parvus. Comparison.between C . c h i l l i w a c k e n s i s and C e r c a r i a  .jaensbhi Johnstone and Cleland(l937) reveals that whereas the former possesses at l e a s t an oesophagus, the d i g e s t i v e system i s e n t i r e l y l a c k i n g i n C.jaenschi. The l a t t e r cere-57. a r i a also attaches to the l i g h t side of a container while C.ch i l l iwackens i s does not attach to any great degree. C .  jaenschi i s found i n Amerianna spp. The above comprise the t o t a l number of dermat i t i s -producing cercariae known at the present time which possess f ive pa ir s of flame c e l l s i n the body. Cercar ia C of Kemp (1919) and the cercar ia of Schistosomatium pathlocopticum Tanabe(l923) are forms i n which the body flame c e l l s number f ive p a i r . These were not described as dermatit is-producers and they also d i f f e r from C.ch i l l iwackens i s i n the type of s n a i l host. Penner(l942) undertook to c l a r i f y the pos i t i on of Cercar ia d o u t h i t t i and the cercar ia of 3.pathlocopticum. He concluded that the two forms were, i n r e a l i t y , synonyms. However, for the sake of the present comparison the c e r c a r i a of S.pathlocopticum w i l l be considered separately . In Cerc-a r i a C of Kemp the penetration glands are arranged i n a d i f -ferent manner about the ventral sucker, while the c e r c a r i a of S.pathlocopticum possesses no f i n - f o l d s . A s f a r a s can be determined these la s t two forms complete the l i s t of known schistosome cercar iae , dermatit is-producers or other-wise, which possess an excretory system comprising f ive pairs of flame c e l l s i n the body and one p a i r i n the t a i l - s t e m . On the basis of the comparisons made above, Cercar ia c h i l l i - wackensis i s described as a species d i s t i n c t from any known form. PLATE V P i g , 1 - u e r c a r i a c h i l l i w a c k e n s i s , showing pos-i t i o n normally a t t a i n e d under a cover-g l a s s . F i g . 2 - P r o t r u s i o n of v e n t r a l sucker of C . c h i l -l i w a c k e n s i s . P i g . 3 - C . c h i l l i w a c k e n s i s , d o r s o - v e n t r a l view, i l l u s t r a t i n g morphology. The e x c r e t o r y system i s shown on one s i d e o n l y , . X denotes p a p i l l a r s p i n e s . — A l l drawings were made f r e e - h a n d — PLATE V r i G 3 PLATE VI Fig.l-Photomicrograph of f r e s h l y k i l l e d C e r c a r i a c h i l l i w a c k e n s i s . X 24 F i g . 2 - C e r c a r i a of F i g . l enlarged. X 60 Fig.3-3porocysts of u . c h i l l i w a c k e n s i s . X 100 PLATE VI 58. CERCARIA 10 (Plate V l l ) Morphology: This i s an apharyngeal, brevifurcate, distome cercaria of the "spindalis group". A l l measurements were made of twenty-five specimens fixed i n 15$ hot formalin. The Means are given with the Standard error: body length .1985 ± .0094 mm; body width .0779 ± .002 mm; tail-stem length .2092 ± .0045 mm; tail-stem width, proximal .0366 ± .0014 mm, d i s t a l .0260 ± .00057 mm; f u r c a l length .0955 ± .0049 mm; f u r c a l p a p i l l a length .0120 ± .00026 mm; o r a l sucker width .0537 ± .0011 mm; ventral sucker .0295 ± .00057 mm, by .0216 ± .00082 mm. The tail-stem of Cercaria 10 i s very s l i g h t l y long-er than the body. While a l i v e the tail-stem of t h i s c e r c a r i a exhibits a marked "wrinkled" appearance. That i s , the cut-i c l e of the tail-stem i s not straight, as i t i s i n most of the other Schistosome cercariae, but a series of indentations occurs down i t s length on both sides. The furcae are extrem-ely c o n t r a c t i l e . Occasionally they were observed to contract to mere lobes, extending at other times to a much greater length. The body of Cercaria 10 i s "spade-shaped" and i s narrowed at the posterior end where i t joins the tail-stem. The proximal portion of the tail-stem i s greater i n width than the narrow posterior region of the body. The oral sucker of the cercaria i s quite protrusable and when viewed a l i v e t h i s organ i s continually being withdrawn into the body and pushed out a n t e r i o r l y . The entire body, tail-stem and furcae are covered 59. w i t h m i n u t e . r e t r o r s e s p i n e s . T h o s e o n t h e body a r e o f u n i f o r m s i z e a n d a r e a s e a s i l y s e e n p o s t e r i o r t o t h e v e n t r a l s u c k e r a s a n t e r i o r t o i t . T h e s p i n e s o n t h e t a i l a r e s p a c e d f a r t h e r a p a r t t h a n t h o s e o n t h e b o d y . C e r c a r i a 10 p o s s e s s e s p a p i l l a r s p i n e s o n t h e b o d y c u t i c l e . T h e p a t t e r n o f t h e s p i n e s a n t e r i o r t o t h e e y e s p o t s c o i n c i d e s w i t h t h a t o f t h e c e r c a r i a o f T . a d a m s i a n d C e r c a r i a  c h i l l i w a c k e n s i s a n d t h e y a r e b i l a t e r a l l y s y m m e t r i c a l . One i s s i t u a t e d o n t h e o r a l s u c k e r b e t w e e n t h e mos t a n t e r i o r p o i n t o f t h e b o d y a n d t h e j u n c t i o n o f t h e o r a l s u c k e r w i t h t h e ; l a t e r a l b o d y c u t i c l e . Two p a p i l l a r s p i n e s a r e l o c a t e d q u i t e c l o s e t o g e t h e r i m m e d i a t e l y p o s t e r i o r t o t h e a b o v e j u n c -t i o n . A n o t h e r i s f o u n d o n t h e l a t e r a l c u t i c l e s l i g h t l y a n t -e r i o r t o t h e l e v e l o f t h e e y e s p o t s . A p a p i l l a r s p i n e was s e e n s l i g h t l y a n t e r i o r t o t h e l e v e l o f t h e v e n t r a l s u c k e r o n t h e same s i d e o f t h e body a s t h e o n e s d e s c r i b e d a b o v e a n d a n o t h e r was o b s e r v e d o n t h e o p p o s i t e s i d e o f t h e b o d y s l i g h t l y p o s t e r i o r t o t h e d i a m e t e r o f t h e v e n t r a l . s u c k e r . T h e p a p i l -l a r s p i n e s o f C e r c a r i a 10 a r e r e a d i l y s e e n a n d a r e more o b -v i o u s t h a n t h o s e o f e i t h e r t h e c e r c a r i a o f T . a d a m s i o r C e r c -a r i a c h i l l i w a c k e n s i s . Two g r a n u l a r e y e s p o t s a r e p r e s e n t i n t h i s c e r c a r i a . T h e s e a r e l o c a t e d a t a p o i n t j u s t a n t e r i o r t o t h e m i d - p o i n t b e t w e e n t h e o r a l a n d v e n t r a l s u c k e r s . The e y e s p o t s a r e n o t e n c l o s e d w i t h i n a d e f i n i t e d e l i m i t i n g s t r u c t u r e a n d i n t h i s r e s p e c t C e r c a r i a 10 d i f f e r s m a r k e d l y f r o m t h e o t h e r c e r c a r i a e d e s c r i b e d i n t h i s w o r k . M i n u t e p i g m e n t a t i o n g r a n u l e s may be s e e n s c a t t e r e d somewhat f r o m t h e p r i n c i p a l b o d y o f t h e e y e -s p o t . The i l l - d e f i n e d n a t u r e o f t h e e y e s p o t s o f t h i s c e r c a r i a i s m a r k e d a n d may be e a s i l y d i s c e r n e d a t f i r s t g l a n c e . 60. The body of ,Cercaria 1 0 contains f i v e pairs of penetration glands. The most anterior gland on each side i s lobed and i s i n th i s respect quite unique. I n i t i a l l y i t was believed that there were three pairs of anterior glands, so d i s t i n c t i s the lobation. Closer examination however, and a count of the number of ducts' leading from the glands, i n -dicated that there were only two pairs of anterior glands, the f i r s t pair being lobed. It was very d i f f i c u l t to deter-mine whether gland one or gland two was the lobed one, but very close examination seemed to indicate that the most ant-erior pair were the lobed ones..The anterior two pairs sur-round the ventral sucker, with pair number two l y i n g d i r e c t l y posterior to this organ. The posterior three pairs of glands are arranged- l i n e a r l y on each side and l i e immediately post-erior to pair number two. A nucleus was observed within each gland. The ducts from the glands extend anteriorly as a compact but large bundle. The connection of the ducts with the most anterior pair of penetration glands i s dorsad. The number of ducts.making up each bundle was observed to be f i v e , i n a cross-sectional view at a flexure. The ducts take a somewhat twisted course and open at the anterior end of the body. At th i s termination f i v e papillae were observed but i t could not be determined whether the ducts opened at the t i p of the papillae or at the i r base. A digestive tract was observed between the penetra-t i o n gland ducts. This consisted of an oesophagus leading from the posterior end of the oral sucker backward to a point approximately half-way between the eyespots and the ventral sucker. Here the oesophagus bifurcated into two very short caeca. The outline of the caeca was best seen when the cerc-a r i a had been subjected to a very d i l u t e solution of neutral 61. red. When this technique had been employed numerous small red granules could be seen within the i n t e s t i n a l caeca. The excretory system of Cercaria 10 i s one of i t s most unique features. It consists of only four pairs of flame c e l l s i n the body and one pair i n the proximal portion of the tail-stem, a l l running into a series of c o l l e c t i n g tubules. Two pairs of flame c e l l s lead into the anterior c o l l e c t i n g tubules (one pair on either side of the eyespots) and two pairs lead into the posterior c o l l e c t i n g tubule. Thus, the flame c e l l pattern of this cercaria i s 2(2+/2+l/). The anterior and posterior l a t e r a l c o l l e c t i n g tubules j o i n at a point l e v e l with the anterior end of the ventral sucker, where they form a main c o l l e c t i n g tubule on either side of the body. The proximal portion of the main c o l l e c t i n g tub-ule i s characterized by two d i s t i n c t regions of convolution and the actual course of the tubule cannot be accurately f o l -lowed through these areas. A c i l i a t e d patch i s located near the point of bifurcation of the main c o l l e c t i n g tubule and also within the c o i l s of the more posterior convolution. The main c o l l e c t i n g tubule runs posteri o r l y where i t joins an excretory bladder near the junction of the body with the tail-stem. The outline of the bladder could not be c l e a r l y observed. A central excretory tubule leaves t h i s bladder and runs medially down the length of the tail-stem. It b i -furcates near the furcae and a tubule leads through each furca to open through an excretory p a p i l l a at the f u r c a l t i p . Associated with the eyespots of Cercaria 10 struc-tures were observed which may represent portions of the ner-vous system. An extremely fine ring surrounds each eyespot and t h i s tends to become extended toward the midline (Plate VII 62. F i g . l ) . T h i s s t r u c t u r e was n o t i c e d a b o u t t h e e y e s p o t s o f t h e c e r c a r i a o f T . a d a m s i a n d C e r c a r i a c h i l l i w a c k e n s i s b u t i t i s much more o b v i o u s a n d e a s i l y s e e n i n C e r c a r i a 1 0 , p r o -b a b l y b e c a u s e o f t h e i l l - d e f i n e d n a t u r e o f t h e e y e s p o t s o f t h e l a t t e r . L e a d i n g l a t e r a l l y f r o m e a c h r i n g a n d c r o s s i n g t h e a n t e r i o r c o l l e c t i n g t u b u l e o f t h e e x c r e t o r y s y s t e m i s a v e r y f i n e s t r u c t u r e w h i c h may be a n e r v e t r a c t . T h i s b i -f u r c a t e s l a t e r a l l y i n t o a n a n t e r i o r a n d p o s t e r i o r " l i n e " . No o t h e r d e t a i l s i n t h i s r e s p e c t c o u l d be o b s e r v e d . The s t r u c t u r e s d e s c r i b e d c o n s i s t m e r e l y o f f i n e r e f r a e t i l e l i n e s a n d a r e v e r y d i f f i c u l t t o o b s e r v e . B e h a v i o r : C e r c a r i a 10 i s m a r k e d l y n e g a t i v e l y g e o t a c t i c . I n g e n e r a l , t h e m a j o r i t y o f t h e c e r c a r i a e i n a v i a l a t a n y one t i m e w i l l be f o u n d c l i n g i n g t o t h e s u r f a c e f i l m by t h e v e n t r a l s u c k e r . . U s u a l l y t h e c e r c a r i a e c a n n o t be s e e n i n n u m b e r s by l o o k i n g t h r o u g h t h e s i d e o f t h e v i a l i n t o t h e w a t e r , t h e c o n -t a i n e r a p p e a r i n g q u i t e d e v o i d o f t h e s e f o r m s . I t i s n e c e s s a r y t o v i e w t h e s u r f a c e o f t h e w a t e r , w i t h a l e n s i f p o s s i b l e , t o a p p r e c i a t e t h e n u m b e r s p r e s e n t w i t h i n t h e v i a l . W h i l e c l i n g i n g t o t h e s u r f a c e many o f t h e c e r c a r i a e r e m a i n m o t i o n -l e s s . T h e y become a c t i v e i s d i s t u r b e d . A f e w o f t h e c e r c -a r i a e a t t a c h t o t h e s i d e o f t h e v i a l . C e r c a r i a 10 a l s o e x -h i b i t s a s l o w , p o s i t i v e r e a c t i o n t o a l i g h t s t i m u l u s . When a s t r o n g l i g h t i s s h o n e i n t o t h e v i a l t h e c e r c a r i a e w i l l a t -t a c h t o t h e s i d e o f t h e v i a l w h e r e t h e s t i m u l u s i s s t r o n g e s t . A s t r o n g l i g h t s t i m u l u s seems t o o b l i t e r a t e t o some e x t e n t t h e i n t e n s e n e g a t i v e g e o t a x i s . -When f r e e s w i m m i n g i n a v i a l t h e e n t i r e c e r c a r i a s w i m s w i t h a s p i r a l m o t i o n d e s c r i b i n g a somewhat c o r k s c r e w p a t h . 6 3 . xhe cercariae may be concentrated i n very large numbers i n the side-arm of the "concentrator" described under "Methods and Apparatus". Under a cover-glass the cercariae hitch along by alternate attachments of the oral and ventral suckers. The body of this cercaria exhibits an amazing a b i l i t y to with-stand unfavorable conditions and usually remains viable long af t e r the tail-stem has become disjoined from the body. In one instance the body remained viable when the water under the cover-glass had nearly completely dried, the dry spots closely surrounding i t . The flame c e l l s could be studied with ease. Dermatitis-Producing A b i l i t i e s ; Cercaria 10 i s a dermatitis-producer, as determined experimentally. This characteristic i s discussed more f u l l y under "Schistosome Dermatitis Experiments". L i f e - c y c l e Experiments: Four white mice, one Guinea pig aged approximately one month, and two ducklings were exposed to Cercaria 10 i n attempts to complete 6 r elucidate the l i f e - c y c l e of t h i s trematode. Two of the mice were exposed both with the "con-centrator" and manually, while two were exposed with the "con-centrator" alone. The Guinea pig was shaved i n the inquinal region and drops of water containing cercariae were applied to t h i s area. Considerable d i f f i c u l t y was experienced i n retaining the water on t h i s region for any length of time. The Guinea pig was also given approximately two dozen cercariae o r a l l y . The duckli naps we re exposed i n a manner similar to 64. that used i n experiments with the cercaria of T.adamsi, and were held i n place for ten minutes. Three of the mice were s a c r i f i c e d sixty and sixty-one days after exposure. One mouse died of an unknown cause on the forty-fourth day. The Guinea pig was s a c r i f i c e d .eightyirtwo days aft e r exposure to the cercariae. The ducklings were k i l l e d f i fty-one days after they had been subjected to the cercariae. A l l attempts to infect laboratory animals with Cercaria 10 were unsuccessful. A d e f i n i t e explanation can-not be put forth to account for t h i s . With the aid of the "concentrator" a f a i r l y large number of cercariae could be brought near the exposed area of the mice. Admittedly, T a l -bot (1936) i n his experimental attempts to inf e c t water fowl with C.elvae, C.physellae and C.stagnicolae, used large num-bers of cercariae and repeated exposures without r e s u l t s . In the experiments with Cercaria 10 the reason for the f a i l u r e of adult worms to become-established i n the animals used must f a l l into one of two categories. Either the conditions for c e r c a r i a l penetration were inadequate ( i . e . i n s u f f i c i e n t cercariae, exposure time too short, wrong area used f o r ex-posure) or the animals used i n the experiments were incapable of acting i n the capacity of the adult host. More experiments would be necessary using larger numbers of cercariae over a greater period of time before mice could be eliminated as a possible adult host for this parasite. Sporocysts: Sporocysts of Cercaria 10 were observed both within 6 5 . a s n a i l h o s t o f t h i s c e r c a r i a w h i c h d i e d p r i o r t o d i s s e c t i o n a n d w i t h i n a s n a i l w h i c h was d i s s e c t e d " i n v i v o " . M e a s u r e -m e n t s w e r e made o f t h e s p o r o c y s t s i n t h e l a t t e r s n a i l a f t e r t h e l a r v a e h a d b e e n k i l l e d w i t h a d r o p o f f o r m a l i n . T h e w i d t h v a r i e d c o n s i d e r a b l y a l o n g i t s l e n g t h . W i d t h s a t t h e w i d e s t p o i n t s v a r i e d f r o m . 0 9 8 mm t o . 1 3 3 mm f o r s i x m e a s u r e -m e n t s . The m i n i m u m w i d t h v a l u e s w e r e . 0 4 2 mm a n d . 0 4 9 mm. The e x a c t l e n g t h o f t h e s p o r o c y s t s c o u l d n o t be d e t e r m i n e d s i n c e t h e o r g a n i s m s w e r e v e r y much i n t e r t w i n e d w i t h e a c h o t h e r a n d t h e y c o u l d n o t be d i s s e c t e d a p a r t w i t h o u t a t e a r o c c u r r i n g somewhere a l o n g t h e l e n g t h . H o w e v e r , t h e l e n g t h p r o b a b l y e x c e e d s 1 6 t i m e s t h e w i d t h a t t h e l a r g e s t p o i n t . T h e m e a s u r e m e n t s o f t h e w i d t h s a r e g i v e n i n T a b l e 8 . T A B L E 8 M e a s u r e m e n t s o f t h e W i d t h o f C e r c a r i a 10. S p o r o c y s t s . W i d t h (mm) R a n g e . 1 3 3 . 0 9 8 . 0 4 2 - . 1 3 3 mm . 1 1 9 . 1 0 5 A v e r a g e . 1 2 6 . 1 1 2 . 0 9 8 mm . 0 4 2 . 0 4 9 S i n c e one o f t h e s n a i l h o s t s o f C e r c a r i a 10 was d i s s e c t e d a l i v e , i t was p o s s i b l e t o o b s e r v e t h e l i v i n g s p o r -o c y s t s . T h i s a l l o w e d t h e c e r c a r i a e t o be o b s e r v e d w h i l e e s c a p i n g f r o m t h e s p o r o c y s t s . . . The e s c a p e was e f f e c t e d by 66. the cercaria hitching along up to the long th i n end of the sporocyst and wriggling vigorously u n t i l i t had squeezed through the long narrow "tubule" (Plate v l l , F i g . 5 ) . Snail Host and Percent Infections: Cercaria 10 emerged from a t o t a l of four s n a i l s , a l l of which have been i d e n t i f i e d as Physa c.f.coniformis. Three of these sna i l s , found on July 4, were collected from Area B. The other was collected on July 29 from Area A. The l a t t e r s n a i l died one day after the cercariae were f i r s t observed emerging and dissection revealed a juvenile leech within the s h e l l . The leech had been collected along with the,snail; beneath the s h e l l of a s n a i l the molluscan leeches are completely hidden and are brought i n with the s n a i l from the f i e l d . Because Cercaria 10 was found i n both Area A and Area B at different times i t i s necessary to consider the percent i n f e c t i o n based on the period delimited by the dates of these two c o l l e c t i o n s . Cercariae were discovered from Area B f i r s t on July 4 and l a s t l y from Area A on July 29. The percent i n f e c t i o n w i l l therefore be considered on the basis of the number of snails collected on and between these dates. Further, the percents are given only on the basis of the number of Physa infected. The number of snails c o l -lected from each area i s given with the dates of c o l l e c t i o n i n Table 9. 67 TABLE 9 Number o f S n a i l s C o l l e c t e d P r o m A r e a s A a n d B , W i t h D a t e s . A r e a A A r e a B D a t e C o l l e c t e d Number D a t e C o l l e c t e d Number J u l y 4 125 J u l y 4 47 J u l y 1 6 89 J u l y 1 6 49 J u l y 25 32 J u l y 29 19 J u l y 29 13 T o t a l P h y s a s 265 109 D u r i n g t h e p e r i o d o f e m e r g e n c e t h r e e s n a i l s w e r e f o u n d i n f e c t e d w i t h C e r c a r i a 10 f r o m A r e a B a n d one f r o m A r e a A . The p e r c e n t a g e o f P h y s a s i n f e c t e d w i t h C e r c a r i a 10 f o r t h e s e two a r e a s i s t h e n ; A r e a B :C e r c a r i a 10 i n A r e a i ; C e r c a r i a 10 i n 1 . 0 7 % o f P h y s a s The a b o v e c a l c u l a t i o n s a r e v a l i d f o r t h e p e r i o d b e t w e e n J u l y 4 a n d J u l y 2 9 , i n c l u s i v e . C o m p a r i s o n W i t h K n o w n P o r m s : A t t h e t i m e o f w r i t i n g , o n l y two d e r m a t i t i s - p r o d -u c i n g c e r c a r i a e h a v e b e e n d e s c r i b e d w h i c h p o s s e s s a n e x c r e t -o r y s y s t e m c o n s i s t i n g o f f o u r p a i r s o f f l a m e c e l l s i n t h e j ~ x 1 0 0 = 2 . 7 5 % o f P h y s a s x 1 0 0 = . 3 7 7 % o f P h y s a s B o t h A r e a s T o g e t h e r ; C e r c a r i a 10 i n 5 T 4 x ioo = 6 8 . b o d y . The e a r l i e s t d e s c r i b e d i s t h e c e r c a r i a o f S c h i s t o s o m a  s p i n d a l i s M o n t g o m e r y 1 9 0 6 ( S o p a r k a r , 1 9 2 1 ) a n d i t has . b e e n d e s c r i b e d o n l y f r o m I n d i a a n d M a l a y a ( S o p a r k a r , 1 9 2 1 ; B u c k l e y , 1 9 3 8 ) a n d S o u t h A f r i c a ( P o r t e r , 1 9 3 8 ) . The o t h e r d e r m a t i t i s -p r o d u c i n g c e r c a r i a * 1 p o s s e s s i n g f o u r p a i r s o f f l a m e c e l l s i n t h e b o d y i s t h e c e r c a r i a o f G i g a n t o b i l h a r z i a h u r o n e n s i s N a j -i m ( 1 9 5 1 ) . A s f a r as c a n be d e t e r m i n e d , o n l y t h r e e o t h e r S c h i s t o s o m e c e r c a r i a e a r e k n o w n w h i c h p o s s e s s a n e x c r e t o r y s y s t e m o f t h i s k i n d a n d t h e s e a r e n o n - d e r m a t i t i s - p r o d u c e r s . C e r c a r i a e i n d i c a e X L V I I S e w e l l ( l 9 2 2 ) h a s b e e n d e s c r i b e d f r o m A c h u r a n d Wynaad i n I n d i a . C e r c a r i a B o f K e m p ( l 9 1 9 ) was d e s c r i b e d f r o m H a m u n - i - H e l m a n d , S e i s t a n i n I n d i a . A n n i e P o r t e r r e p o r t e d t h e d i s c o v e r y i n A f r i c a o f a S c h i s t o s o m e c e r c a r i a w h i c h was p h o t o p h o b i c . T h i s c e r c a r i a was d e s i g -n a t e d a s C . e l a n d s i a e a n d i t p o s s e s s e d f o u r p a i r s o f b o d y f l a m e c e l l s . The c e r c a r i a o f G . h u r o n e n s i s i s t h e o n l y c e r c -a r i a w i t h t h i s t y p e o f e x c r e t o r y s y s t e m w h i c h h a s b e e n f o u n d i n t h e p a s t i n t h e W e s t e r n H e m i s p h e r e . A c o m p a r i s o n w i l l be made b e t w e e n t h e a b o v e f o r m s a n d C e r c a r i a 1 0 . The c e r c a r i a o f S . s p i n d a l i s p r o d u c e s a d e r m a t i t i s w h i c h i s c o n t r a c t e d by w o r k e r s i n t h e p a d i s o f M a l a y a , w h e r e i t i s k n o w n a s " s a w a h i t c h " . B u c k l e y d e s c r i b e d t h e d e r m a -t i t i s a s o n e w h i c h i s c o n t r a c t e d i n t h e m o r n i n g a n d becomes e v i d e n t i n t h e e v e n i n g . The c e r c a r i a o f S . s p i n d a l i s i s s i m -i l a r i n m a c r o s c o p i c a p p e a r a n c e t o C e r c a r i a 1 0 . The f u r c a e a r e c o m p a r a t i v e l y s h o r t . T h e b o d y s p i n a t i o n , a s d e s c r i b e d by S o p a r k a r , i s e s p e c i a l l y m a r k e d a t t h e a n t e r i o r p o r t i o n o f t h e b o d y . F u r t h e r , t h e o r a l o r g a n i s p r o t r u s a b l e . The i n t e s t i n a l c a e c a o f t h i s c e r c a r i a c o n t a i n g r a n u l a r m a t e r i a l w h i c h s t a i n s w i t h i n t r a v i t a m n e u t r a l r e d . T h e c e r c a r i a v a r i e s i n o t h e r r e s p e c t s f r o m C e r c a r i a 10 t o s u c h a d e g r e e 69. t h a t p o s s i b l e s y n o n y m i t y i s e l i m i n a t e d . T h e c e r c a r i a o f S . s p i n d a l i s p o s s e s s e s no e y e s p o t s . The t a i l - s t e m i s much l o n g e r p r o p o r t i o n a l l y t h a n t h e body a s c o m p a r e d w i t h t h e same r a t i o i n C e r c a r i a 1 0 . I n a d d i t i o n , t h e a n t e r i o r two p a i r s o f p e n e t r a t i o n g l a n d s a r e b o t h l o c a t e d i n f r o n t o f t h e v e n t r a l s u c k e r i n t h e c e r c a r i a o f S . s p i n d a l i s . T h e s n a i l h o s t o f t h e l a t t e r i s P i a n o r b i s e x u s t i s w h i c h i s n o t a P h y s i d s n a i l . The b e h a v i o r p a t t e r n o f t h e c e r c a r i a o f S .  s p i n d a l i s i s q u i t e d i f f e r e n t f r o m t h a t o f C e r c a r i a 1 0 . The l a t t e r a r e f o u n d c l i n g i n g t o t h e s u r f a c e f i l m w h i l e t h e f o r -mer h a n g i n t h e w a t e r w i t h t h e b o d y d o w n w a r d a n d g r a d u a l l y s i n k , o n l y t o s w i m u p w a r d s a g a i n i n t e r m i t t a n t l y . The c e r c a r i a w h i c h mos t c l o s e l y r e s e m b l e s C e r c a r i a  10 i s t h a t o f G i g a n t o b i l h a r z i a h u r o n e n s i s N a j i m ( l 9 5 1 ) . So c l o s e i s t h e r e s e m b l a n c e t h a t t h e two may i n f u t u r e be f o u n d t o be s y n o n y m o u s . T h e b e h a v i o r p a t t e r n o f t h e two c e r c a r i a e i s e s s e n t i a l l y t h e s a m e . T h e c e r c a r i a o f G . h u r o n e n s i s i s f o u n d i n P h y s a g y r i n a . The b o d y p r o p o r t i o n s a r e s i m i l a r t o t h o s e o f C e r c a r i a 1 0 , t h e f u r c a e b e i n g s h o r t e r t h a n h a l f t h e l e n g t h o f t h e t a i l - s t e m a n d t h e t a i l - s t e m l e n g t h v e r y s l i g h t l y e x c e e d i n g t h a t o f t h e b o d y . N a j i m d e s c r i b e d t h e c e r c a r i a a s p o s s e s s i n g p a p i l l a r s p i n e s o n t h e s i d e o f t h e b o d y . H o w e v e r , o n l y t h r e e o f t h e s e w e r e a p p a r e n t l y s e e n o n o n e s i d e , w i t h o n e o n t h e o p p o s i t e s i d e . T h e y a r e l o c a t e d i n p o s i t i o n s c o r r e s p o n d i n g w i t h some o f t h e s t r u c t u r e s f o u n d o n C e r c a r i a 1 0 . The r e l a t i v e p o s i t i o n s o f t h e p a p i l l a r s p i n -a t i o n o n t h e two c e r c a r i a e a r e i l l u s t r a t e d b e l o w . 70. Cercaria of Cercaria 10. G.huronensis. Within the body further s i m i l a r i t i e s between the two cercariae become apparent. Both possess f i v e pairs of penetration glands. Najim stated that the second p a i r of glands i s t r i - l o b e d . Cercaria 10 i s described as possess-ing lobation i n the f i r s t pair of glands. Either one of the cercariae has been in c o r r e c t l y described, or the cerc-ariae are two separate forms. The question must, for the moment, remain an open one. The excretory system of the cercaria of G.huronensis i s essentially the same as that of Cercaria 10. However, the two regions of marked convolution i n the main c o l l e c t i n g tubules of Cercaria 10 are not des-cribed as occurring i n Najim's cercaria. He does state how-ever,that the elements of the excretory system of his cerc-a r i a were found occasionally to vary considerably i n posi-t i o n . In the author's own words,"Variations i n the position of the flame c e l l s and the looping of the tubules were not-iced quite often". The number of flame c e l l s he states, were even found to vary, an "extra" one being noted at times pos-t e r i o r to the ventral sucker. It i s possible that a c i l -71. iated patch was mistaken for a flame c e l l i n t h i s l a t t e r case, but i t i s equally possible that the cercaria actually possessed a greater number of flame c e l l s than were describ-ed by Najim. This author also mentions that the t h i r d and fourth flame c e l l s "might come closer together i n p o s i t i o n " . In view of this high degree of "variation" i t seems undes-ira b l e to eliminate the p o s s i b i l i t y of there 'being more than four pairs of body flame c e l l s i n t h i s cercaria. The cerc-a r i a of G.gyrauli Brackett(1940), belonging to the same genus as. Najim describes for his organism, possesses s i x pairs of flame c e l l s i n the body. The adult worm of Gigantobilharzia huronensis was experimentally established i n chickens and canaries. It was found i n naturally infected goldfinches and cardinals. The p r i n c i p a l points of difference between Cercaria 10 and the cercaria of G.huronensis are as follows; Najim*s cercaria i s described as possessing a f a i r l y large "brain"' with the l a t e r a l lobes surrounding the eyespots. This struc-ture was not observed to be so extensive i n Cercaria 10. In the l a t t e r cercaria the nervous system, already described, encloses the eyespots very closely (Plate V l l , P i g . 1 ) . This i s perhaps one of the most obvious differences between the two cercariae. Najim states that the bifurcation of the oesophagus of his cercaria i s incomplete or bulb-like. The bifurcation of the oesophagus of Cercaria 10 was observed to be d i s t i n c t and a number of granules were seen within the short caeca. Further, Najim described r e l a t i v e l y few p a p i l -l a r spines on the body of his cercaria. More of these struc-tures were observed on Cercaria 10. 4 7 2 . I t seems p r o b a b l e t h a t C e r c a r i a 10 f a l l s w i t h i n t h e g e n u s G i g a n t o b i l h a r z i a o n t h e b a s i s o f c o m p a r i s o n w i t h t h e c e r c a r i a o f G . h u r o n e n s i s a l t h o u g h t h i s c a n n o t be d e f i n i -t e l y e s t a b l i s h e d u n t i l t h e a d u l t o f C e r c a r i a 10 i s k n o w n . O n l y two o t h e r members o f t h e g e n u s G i g a n t o b i l h a r z i a h a v e b e e n d e s c r i b e d . T h e s e w e r e r e p o r t e d by B r a c k e t t ( 1 9 4 2 ) . T h i s a u t h o r d e s c r i b e d t h e l i f e - c y c l e o f G . g y r a u l i a n d t h e a d u l t s o f G . l a w a y i . As p r e v i o u s l y m e n t i o n e d , t h e c e r c a r i a o f G . g y r a u l i p o s s e s s e s s i x p a i r s o f f l a m e c e l l s i n t h e b o d y . T h e p o s s i b i l i t y o f s y n o n y m i t y b e t w e e n N a j i m ' s c e r c a r i a a n d C e r c a r i a 10 c a n n o t be o v e r l o o k e d . I t i s t h e r e f o r e a d v i s a b l e t o l e a v e t h e q u e s t i o n a n o p e n o n e u n t i l f u t u r e work ' c a n be c a r r i e d o u t w i t h C e r c a r i a 1 0 . The o t h e r s p e c i e s d e s c r i b e d w i t h f o u r b o d y f l a m e c e l l s a r e n o t d e r m a t i t i s - p r o d u c e r s , o r r a t h e r t h e y h a v e n o t b e e n d e s c r i b e d a s s u c h t o d a t e . H o w e v e r , a c o m p a r i s o n w i l l be made a t t h i s t i m e b e t w e e n t h e s e f o r m s a n d C e r c a r i a 10 s i n c e t h e number o f c e r c a r i a e k n o w n t o p o s s e s s t h i s t y p e o f . f l a m e c e l l p a t t e r n i s so s m a l l . C e r c a r i a e i n d i c a e X L V I I p o s s e s s e s no f u r c a l f i n - f o l d s a n d i n t h i s r e s p e c t d i f f e r s f r o m C e r c a r i a 10 t o t h e g r e a t e s t e x t e n t . T h e m a c r o s c o p i c a p p e a r a n c e o f t h i s c e r c a r i a i s s t r i k i n g l y s i m i l a r t o t h a t o f C e r c a r i a 1 0 . T h e a p p e a r a n c e o f t h e e y e s p o t s i s s i m i l a r t o t h a t o f t h e C u l t u s L a k e c e r c a r i a i n t h a t t h e r e i s a m a r k -ed d e g r e e o f g r a n u l a t i o n . F u r t h e r , t h e p e n e t r a t i o n g l a n d s , a l t h o u g h p o s s e s s i n g no l o b a t i o n , a r e a r r a n g e d i n a s i m i l a r p a t t e r n a b o u t t h e v e n t r a l s u c k e r , w i t h r e s p e c t t o t h o s e o f C e r c a r i a 1 0 . T h e p o s t e r i o r p o r t i o n o f t h e b o d y i s somewhat b u l b o u s , n a r r o w i n g down g r e a t l y a t t h e p o i n t o f j u n c t i o n w i t h t h e t a i l - s t e m . Kemp , i n h i s d e s c r i p t i o n o f C e r c a r i a B s t a t e d t h a t 1 t h i s form i s closely related to Cercariae indicae X L V I I . Cercaria B d i f f e r s markedly from Cercaria 10 i n that the former possesses a pair of un-pigmented eyespots. Further, no trace of a digestive tract could be seen by Kemp i n his observations. Kemp's description of th i s cercaria, although a valuable contribution to the f i e l d at the time of p u b l i -cation, i s quite vague i n comparison with the precise des-criptions found i n more modern works, and i s highly inade-quate f o r comparative purposes. It i s not d i f f i c u l t to distinguish between Cercaria  10 and G.elandsiae Porter(1938). The former i s markedly p o s i t i v e l y phototactie while the l a t t e r i s photophobic. While the number of flame c e l l s i n the excretory system i s the same for both, the position of these flame c e l l s d i f f e r s quite d i s t i n c t l y i n the two forms. The course'of the main c o l l e c t i n g tubule of these cercariae varies with each case to a considerable degree. ! PLATS V l l P i g . l - C e r c a r i a 1 0 showing nervous circum-ocular r i n g s and s t r u c t u r e s which may be nerve t r a c t s . F i g . 2 - E x c r e t o r y p a p i l l a on f u r c a t i p of C e r c a r i a 1 0 Fig,3-End of sporocyst of C e r c a r i a 1 0 showing method of escape of c e r c a r i a e . F i g . 4 - C e r c a r i a 1 0 , d o r s o - v e n t r a l view, i l l u s t r a t i n g morphology. The excretory system i s shown on one side only, with p e n e t r a t i o n glands shown only on opposite s i d e f o r c l a r i t y . X denotes p a p i l l a r s p i n e s . — A l l drawings were made f r e e - h a n d — PLATE V l l l Fig.l-Photomicrograph of C e r c a r i a 10 s p o r o c y s t s . X 40 Fig.2-Sporocysts of F i g . l enlarged.X 100 Fig.3-Photomicrograph of f r e s h l y k i l l e d C e r c a r i a 10. X 100 F I G . 3 PLATE V l l l 74. PAPILLAR SPINATION. As f a r as can be determined, p a p i l l a r spination such as i s found on the Cultus Lake trematodes has never been described i n the past on adult Schistosomes. The occurrence of similar spines on Schistosome cercariae has been describ-ed only seldom i n the past. Szidat i n 1929 and Gordon i n 1934 reported the occurrence of similar spines on Schistosome cercariae(Najim,195l). The former observed what he c a l l e d "sense-bristles" on the cercaria of B tpolonica. Gordon re-ported spines on the cercaria of Schistosoma mansoni and S.haematobium. Wall(1941) reported the presence of similar spines on the cercaria of Spirorchis elephantis. This author described the cercaria as also possessing p a p i l l a r spines on the tail-stem. ¥ercammen-Granjean(195l) published a pap-er i n which he stated that he observed long spines with basal papillae on the body of the cercaria of Schistosoma mansoni. He included i l l u s t r a t i o n s of t h i s spination and these struc-tures appear very similar to those observed on the three Cultus Lake forms. However, the h a i r - l i k e projection on the papillae appears very much longer and f i n e r than this struc-ture on the Cultus Lake cercariae. Granjean's observations were made with a magnification of 1470X, a considerably higher magnification than the s l i g h t l y less than 1000X used to ob-serve the l o c a l forms. Granjean stated that i t was of p r i -mary importance that the cercariae be studied " i n vivo" and at the correct temperature (30°C). He also emphasized that the cercariae were studied i n human serum. Twenty-four pap-i l l a r spines were described on the body of the cercaria. These were not a l l i n the same plane but were symmetrical i n t h e i r arrangement. No spines were located on the extreme l a t e r a l "edge" of the body, being above and below th i s plane. 75. Granjean's observations were confirmed by J.J.C.Buckley of the school of.Hysiene and Tropical Medicine of London. Fur-ther, the author stated that i n a private correspondance Buckley informed him he had observed similar spines on the cercaria of Schistosoma bovis. Granjean also indicated that i n 1934 Gordon, Davey and Peaston observed similar spines on the tail-stem of S.mansoni. Najim(l95l), i n his description of the l i f e history of Gigantobilharzia huronensis, reported the occurrence of p a p i l l a t e spines on the body of the cercaria of this species. Three spines were seen on one side and one on the other side, as i l l u s t r a t e d i n his drawing of the cercaria. These spines are located i n positions which coincide with some, of those on the Gultus Lake forms, but more spines were observed on the l a t t e r . Morphology of Spination on Cultus Lake Cercariae; The p a p i l l a r spination of the Trematodes described i n the present work can be viewed only'with the use of o i l -immersion. Further, i t i s necessary that the observations be made immediately after the cercariae are put beneath a cover-glass as a wet-mount. The spines tend to disintegrate very early during the course of the observation. There are a number of points of s i m i l a r i t y between this type of spination on the three Cultus Lake Trematodes. The p a p i l l a r spines possess at t h e i r base a minute dome-like p a p i l l a projecting s l i g h t l y from the c u t i c l e . The size of these papillae varies. They are usually largest near the anterior end of the body. The spines are present as an ex-76. t r e m e l y f i n e " h a i r " o r p r o j e c t i o n a t t h e a p e x . T h e p r o j e c -t i o n s v a r y i n l e n g t h f r o m a m i n i m u m t h e same l e n g t h a s t h e p a p i l l a i s h i g h , t o a b o u t f o u r o r more t i m e s t h e h e i g h t o f t h e p a p i l l a . T h e l o n g e r " h a i r s " o r s p i n e s a r e v e r y much t h i n n e r t h a n t h e s h o r t e r o n e s a n d t h e y a p p e a r a l m o s t a s s h a d -o w s . I n g e n e r a l ; t h e p a p i l l a t e d s p i n e s a r e more o b v i o u s l y s e e n n e a r t h e a n t e r i o r p o r t i o n o f t h e b o d y . T w i c e w h i l e o b s e r v i n g C e r c a r i a c h i l l i w a c k e n s i s some o f t h e h a i r - l i k e p r o j e c t i o n s o n t h e p a p i l l a e w e r e o b s e r v e d t o be u n d e r g o i n g a v i b r a t o r y m o t i o n . T h e p a p i l l a r s p i n e s o n t h e a n t e r i o r h a l f o f t h e b o d y , a n d p r o b a b l y a l s o f u r t h e r p o s t e r i o r , a r e b i l a t e r a l l y s y m m e t -r i c a l . On e a c h s i d e o f t h e b o d y t h e c e r c a r i a e p o s s e s s o n e s p i n e b e t w e e n t h e mos t a n t e r i o r p o i n t a n d t h e j u n c t i o n o f t h e l a t e r a l c u t i c l e w i t h t h e o r a l s u c k e r ; two s p i n e s c l o s e t o -g e t h e r j u s t p o s t e r i o r t o t h e a b o v e j u n c t i o n ; o n e s p i n e b e -t w e e n t h e a b o v e p a i r a n d t h e l e v e l o f t h e e y e s p o t s ; a n d f u r -t h e r p o s t e r i o r i n t h e r e g i o n o f t h e v e n t r a l s u c k e r , o t h e r s p i n e s a r r a n g e d i n v a r i o u s p a t t e r n s . T h e abov.e p a t t e r n o f p a p i l -l a r s p i n a t i o n i s common t o t h e t h r e e t y p e s o f c e r c a r i a e d e s -c r i b e d h e r e i n , r e g a r d l e s s o f t h e o b v i o u s d i s s i m i l a r i t i e s o f t h e s e c e r c a r i a e i n o t h e r r e s p e c t s . T h e p o s i t i o n o f t h e s p i n e s v a r i e s w i t h t h e d i f f e r e n t c e r c a r i a e i n o n e r e s p e c t o n l y . T h o s e p a p i l l a r s p i n e s l o c a t e d p o s t e r i o r t o t h e l e v e l o f t h e e y e s p o t s a r e n o t l o c a t e d i n s i m i l a r p o s i t i o n s i n t h e t h r e e c e r c a r i a e . T h e p o s i t i o n s o f t h e s e more p o s t e r i o r p a p i l l a r s p i n e s a r e c h a r a c t e r i s t i c f o r e a c h o f t h e c e r c a r i a o f T . a d a m -s i , C e r c a r i a c h i l l i w a c k e n s i s a n d C e r c a r i a 10 a s i l l u s t r a t e d i n P l a t e s 1 1 1 , V a n d V l l . 77. T h e p a p i l l a r s p i n e s a r e n o t a l l l o c a t e d o n t h e same p l a n e . M u c h f o c u s i n g i s n e c e s s a r y i n o r d e r t h a t t h e s e s p i n e s may be s e e n a n d v e r y r a r e l y do more t h a n two o r t h r e e s p i n e s a p p e a r o n t h e same p l a n e o f f o c u s . On C e r c a r i a 1 6 A , d e s -c r i b e d o n p a g e 4 5 , a " t r i a n g l e " f o r m e d by t h r e e p a p i l l a r s p i n -es was o b s e r v e d n e a r t h e j u n c t i o n of. t h e o r a l s u c k e r w i t h t h e l a t e r a l c u t i c l e . F u r t h e r , a p a p i l l a r s p i n e was o b s e r v e d o n t h e d o r s a l s u r f a c e o f t h i s c e r c a r i a i m m e d i a t e l y a d j a c e n t t o t h e p o s t e r i o r edge o f t h e o r a l s u c k e r . On a f e w o c c a s i o n s w h i l e t r i e w i n g t h e v e n t r a l s u r f a c e o f C e r c a r i a c h i l l i w a c k e h -s i s , a p a p i l l a r s p i n e was o b s e r v e d o n t h e v e n t r a l c u t i c l e by f o c u s i n g u p w a r d s . T h i s s p i n e was l o c a t e d midway b e t w e e n t h e l a t e r a l b o d y c u t i c l e a n d t h e v e n t r a l s u c k e r , a t a l e v e l w i t h t h e p o s t e r i o r edge o f t h e l a t t e r . The s p i n e s s i t u a t e d u p o n t h e a p e x o f t h e m i n u t e p a p -i l l a e d i s i n t e g r a t e , c o n s i d e r a b l y i n a d v a n c e o f t h e d e a t h p o i n t o f t h e c e r c a r i a . O c c a s i o n a l l y t h e m i n u t e s p i n e was o b s e r v e d t o b e n d o v e r a n d d i s i n t e g r a t e p r i o r t o t h e d e a t h p o i n t . J u s t b e f o r e t h e d e a t h p o i n t o f t h e c e r c a r i a o n l y t h e p a p i l l a e a r e s e e n , w h i l e a f t e r t h e c e r c a r i a h a s . d i e d t h e s e p a p i l l a e a r e l o c a t e d o n l y w i t h g r e a t d i f f i c u l t y a n d h a v e u s u a l l y d i s a p p e a r e d c o m p l e t e l y . T h e l i f e - c y c l e e x p e r i m e n t s u n d e r t a k e n w i t h t h e c e r c -a r i a o f T . a d a m s i r e v e a l e d t h a t t h e p a p i l l a r s p i n a t i o n i s c a r -r i e d o v e r i n t o t h e a d u l t s t a g e o f t h i s f o r m . T h e p a t t e r n o f t h e more a n t e r i o r s p i n e s o f t h e c e r c a r i a i s r e t a i n e d i n t h e a d u l t ( P l a t e 1 1 ) . The s p i n e s o f t h e a d u l t T . a d a m s i a r e s l i g h t -l y more d i f f i c u l t t o o b s e r v e t h a n t h o s e o f t h e c e r c a r i a . 78. D u r i n g t h e s u r v e y o f t h e O k a n a g a n V a l l e y i n 1 9 5 2 a n o t h e r c e r c a r i a was d i s c o v e r e d w h i c h b o r e p a p i l l a r s p i n e s i n a v e r y s i m i l a r p a t t e r n t o t h a t o f t h e C u l t u s L a k e f o r m s . T h e e x a c t i d e n t i t y o f t h e O k a n a g a n c e r c a r i a h a s n o t b e e n d e t e r m i n e d b u t i t b e l o n g s t o t h e " d o u t h i t t i g r o u p " p o s s e s s i n g a s f a r a s c o u l d be o b s e r v e d a t t h e t i m e , f i v e p a i r s o f f l a m e c e l l s i n t h e b o d y . T h e b e h a v i o r p a t t e r n o f t h e O k a n a g a n c e r c -a r i a c o i n c i d e d w i t h t h e b e h a v i o r d e s c r i b e d f o r t h e c e r c a r i a o f • G . h u r o n e n s i s N a j i m , C e r c a r i a d o u t h i t t i C o r t a n d C e r c a r i a 1 0 , a n d i n d e e d t h e c e r c a r i a may be s y n o n y m o u s w i t h one o f t h e s e f o r m s . The s i g n i f i c a n c e o f t h e p a p i l l a r s p i n a t i o n i s n o t a t a l l c e r t a i n . I t i s p o s s i b l e t h a t t h e s e s t r u c t u r e s h a v e b e e n m e r e l y o v e r - l o o k e d by o t h e r w o r k e r s i n t h e p a s t . T h e p o s s i b -i l i t y a l s o e x i s t s t h a t c e r c a r i a e p o s s e s s i n g t h i s t y p e o f s p i n -a t i o n a r e e n t i r e l y s e p a r a t e f o r m s f r o m t h o s e d e s c r i b e d w i t h o u t t h e m , a n d a r e a c t u a l l y new s p e c i e s . To t h e a u t h o r ' s m i n d , i t seems h i g h l y u n l i k e l y t h a t a w o r k e r who i s f a m i l i a r w i t h c e r c -a r i a e a n d who h a s b e e n s t u d y i n g t h e m f o r some t i m e c o u l d d e s -c r i b e a c c u r a t e l y t h e m i n u t e r e t r o r s e s p i n a t i o n o n t h e b o d y o f a c e r c a r i a a n d o v e r - l o o k t h e l a r g e r , more c o m p l e x p a p i l l a r s p i n e s . T h e o n l y r e a s o n a b l e e x p l a n a t i o n f o r t h e p o s s i b l e f a i l -u r e o f p r e v i o u s w o r k e r s t o o b s e r v e p a p i l l a r s p i n e s o n c e r c a r i a e seems t o l i e i n t h e f a c t t h a t t h e p a p i l l a r s p i n e s d i s i n t e g r a t e s o o n a f t e r t h e o r g a n i s m s h a v e b e e n p l a c e d u n d e r a c o v e r - g l a s s . P e r h a p s i n i t i a l c o n c e n t r a t i o n by a w o r k e r o n some o t h e r m o r -p h o l o g i c a l a s p e c t o f t h e c e r c a r i a i n v i e w a l l o w e d a n y p a p i l -l a r s p i n e s w h i c h m i g h t h a v e b e e n p r e s e n t t o d i s i n t e g r a t e b e -f o r e t h e a t t e n t i o n was f o c u s e d o n t h e m . 79. TAXONOMIC D I S C U S S I O N . Taxonomy o f t h e A d u l t T r i c h o b i l h a r z i a a d a m s i . P r i c e ( l 9 3 0 ) i n h i s d e s c r i p t i o n o f t h e f a m i l y S c h i s t - o s e mat i d a e . d i v i d e d t h e g r o u p i n t o two s u b f a m i l i e s — t h e S c h i s t o s o m i n a e a n d t h e B i l h a r z i e l l i n a e . T h e S c h i s t o s o m i n a e i n c l u d e s f e m a l e worms w h i c h a r e r o u n d i n c r o s s - s e c t i o n , w h i l e t h e worms o f t h e B i l h a r z i e l l i n a e a r e more o r l e s s f l a t t e n e d , e s p e c i a l l y i n t h e more p o s t e r i o r r e g i o n s o f t h e b o d y . F u r -t h e r , t h e i n t e s t i n a l c a e c a o f t h e S c h i s t o s o m i n a e u n i t e c a u -d a d o f t h e e q u a t o r o f t h e b o d y , w h i l e t h o s e o f t h e o t h e r s u b -f a m i l y u n i t e more a n t e r i o r l y . I t i s a p p a r e n t t h e r e f o r e t h a t t h e a d u l t S c h i s t o s o m e d e s c r i b e d i n t h e p r e s e n t w o r k i s a mem-b e r o f t h e B i l h a r z i e l l i n a e , o n t h e b a s i s o f t h e f l a t n e s s o f t h e b o d y a n d t h e m o r p h o l o g y o f t h e i n t e s t i n a l c a e c a . T h e g e n e r a o f t h e s u b f a m i l y B i l h a r z i e l l i n a e w e r e l i s t e d by P r i c e a s B i l h a r z i e l l a , G i g a n t o b i l h a r z i a , D e n d r i t o -b i l h a r z i a a n d T r i c h o b i l h a r z i a . The d e s c r i p t i o n o f B i l h a r z i e l -l a s t a t e d t h a t t h e p o s t e r i o r o f t h e b o d y i s d i s t i n c t l y f l a t -t e n e d , t h u s i n f e r r i n g t h a t t h e more a n t e r i o r r e g i o n s o f t h e b o d y w e r e n o t a s f l a t t e n e d . The d e s c r i p t i o n d o e s n o t c o i n c i d e w i t h t h a t o f t h e l o c a l w o r m . F u r t h e r , t h e B i l h a r z i e l l a s p e c -i e s d e s c r i b e d by P r i c e a r e n o t a s g r e a t l y e l o n g a t e d w i t h r e -s p e c t t o t h e i r w i d t h a s i s t h e p r e s e n t w o r m . T h e worms o f G i g a n t o b i l h a r z i a a r e somewhat c y l i n d r i c a l a n d do n o t p o s s e s s s u c k e r s . D e n d r i t o b i l h a r z i a p o s s e s s e s a c u t i c l e d e v o i d o f s p i n e s a n d s u c k e r s a r e a b s e n t . I n a d d i t i o n , t h e s e worms p o s -s e s s a d i g e s t i v e c a e c u m w i t h l a t e r a l c a e c a e x t e n d i n g f r o m i t . P r i c e ' s d e s c r i p t i o n o f t h e g e n u s T r i c h o b i l h a r z i a was q u i t e i n a d e q u a t e f o r c o m p a r i s o n w i t h o t h e r f o r m s . B e t w e e n t h e t i m e 80. of publication of Price's paper and the.McMullen and Beaver publication(l945) of the description of the adults of C.stag-nicolae, C.physellae and C.elvae, another genus became est-ablished by Ejsmont(Brackett,1942). This was Pseudobilharz-i e l l a . McMullen and Beaver revised the genus T r i c h o b i l h a r z i a and included under this description the. former genus Pseudo-b i l h a r z i e l l a . For this reason.the l a t t e r genus i s mentioned only b r i e f l y at this time. Of great importance was the description given by McMullen and Beaver of the s p e c i f i c dia-gnosis of the revised genus Trich o b i l h a r z i a , and on the basis of t h i s description an adequate comparison can be made be-tween th i s generic diagnosis and the worm being described at present. On the basis of this comparison and comparison with i l l u s t r a t i o n s of the adult T.stagnicolae, T.physellae and T.ocellata our worm i s diagnosed as Tr i c h o b i l h a r z i a . Taxonomy of the Cultus Lake Cercariae. The taxonomic position of cercariae has i n the past been determined on the basis of a number of c r i t e r i a . Faust (1924) stated that the position of the flukes should be de-termined on the basis of a system which i s carried through the entire l i f e - c y c l e with a minimum of change. The only system of which th i s can be said, as observed by Faust, i s the excretory system. On the basis of embryological develop-ment and morphology the excretory system of furcocercous cerc-ariae i s probably the most primitive of a l l types(Hussey,1941). Relatively l i t t l e change occurs i n the excretory structures throughout the l i f e - c y c l e of the fluke. On the other hand, Dawes(1946) stated that the flame c e l l "formula" does not designate phylogenetic relationships between cercariae, while Harper(l929) was of the co/pinion that the excretory system 81. i s n o t a n i n f a l l i b l e r g u i d e i n c e r c a r i a l d i a g n o s i s . T h e e x c r e t o r y s y s t e m i s u s u a l l y e x t r e m e l y d i f f i c u l t t o t r a c e w i t h a n y d e g r e e o f a c c u r a c y . F u r t h e r , S t u n k a r d ( l 9 2 9 ) o b -s e r v e d t h a t c e r t a i n a d d i t i o n s t o t h e e j s c r e t o r y s y s t e m do o c -c u r d u r i n g t h e t r a n s i t i o n f r o m c e r c a r i a t o a d u l t . Most a u t h o r s i n t h e p a s t h a v e b a s e d much o f t h e i r d e s c r i p t i v e w o r k u p o n t h e s p e c i f i c m e a s u r e m e n t s o f c e r c a r i a e . V a r i o u s c e r c a r i a e h a v e b e e n s e p a r a t e d a n d c o n s i d e r e d s e p a r -a t e s p e c i e s b e c a u s e t h e y w e r e . " s m a l l e r " o r " l a r g e r " t h a n a n -o t h e r s i m i l a r f o r m . One g r e a t d i f f i c u l t y i n t h i s r e s p e c t h a s b e e n t h a t t h e c e r c a r i a e a r e v e r y c o n t r a c t i l e a n d t h e r e i s u s u a l l y a w i d e r a n g e o f m e a s u r e m e n t s f o r a n y g i v e n d i m e n s i o n . P o r t e r ( l 9 3 8 ) r e p o r t e d t h a t s h e h a d f o u n d t h e c e r c a r i a o f S .  s p i n d a l i s i n S o u t h A f r i c a , b u t t h e m e a s u r e m e n t s o f t h i s c e r c -a r i a w e r e l e s s t h a n t h o s e o f t h e I n d i a n s t r a i n , p a r t i c u l a r l y t h e l e n g t h o f t h e t a i l - s t e m . On t h i s b a s i s s h e p r o p o s e d t h a t t h e A f r i c a n c e r c a r i a be c o n s i d e r e d a s a v a r i e t y a f r i c a n a . N e u h a u s ( l 9 5 2 ) i n e x p e r i m e n t s w i t h t h e c e r c a r i a o f T r i c h o b i l -h a r z i a s z i d a t i f o u n d t h a t " t h e c e r c a r i a e o f v a r i o u s i n t e r m e d -i a t e h o s t i n d i v i d u a l s o f t h e same k i n d a n d t h e same o r i g i n a r e d i f f e r e n t " . . He a l s o s t a t e d t h a t c e r c a r i a l m o d i f i c a t i o n s o c c u r i n e a c h i n d i v i d u a l i n t e r m e d i a t e h o s t u n d e r t h e i n f l u -e n c e o f i n d i v i d u a l v a r i a t i o n s o f t h e h o s t , a n d t h e a g e o f t h e h o s t i n f l u e n c e s t h e d e v e l o p m e n t a l t i m e o f t h e p a r a s i t e . N e u -h a u s o b s e r v e d t h a t one c o u l d c o r r e l a t e t h e d i f f e r e n t d e v e l o p -ment t i m e s w i t h l a r g e d i f f e r e n c e s i n t h e c e r c a r i a e . I t w o u l d seem t h e r e f o r e , t h a t m e a s u r e m e n t s of t h e d i m e n s i o n s o f c e r c -a r i a e do n o t f o r m a r e l i a b l e s o u r c e o f c r i t e r i a u p o n w h i c h t o b a s e c o m p a r i s o n s . M i l l e r ( l 9 2 6 ) o u t l i n e d a s y s t e m f o r g r o u p i n g S c h i s t -82. osorae cercariae based on a similar system previously put forth by Sewell. This grouping i s based on the flame c e l l pattern of the cercariae, as well as upon other data, and i s given as follows for the cercariae known i n 1926. GROUP A.-Human Schistosomes, possessing three pairs of flame c e l l s i n the body. GROUP B.-Cercaria B of Kemp. Cercaria of Schistosoma s p i n d a l i s . Cercariae indicae XLVII This group i s characterized by the presence of four pairs of flame c e l l s i n the body. The group was modified from the o r i g i n a l of Sewell by the addition of Cercaria B, the excretory system of wtiich was unknown when the group was formed. GROUP C.-Cercaria d o u t h i t t i . Cercaria C of Kemp. Cercaria of Schistosomatium pathlocopticum. O r i g i n a l l y Sewell created t h i s group to also include Cercaria elephantis but M i l l e r gave th i s a separate grouping. Group C i s character-ized by the presence of f i v e pairs of flame c e l l s i n the body of the cercaria. Sewell(1922) stat-ed that "no forms corresponding to thi s group have been found i n India". GROUP D.-Cercaria o c e l l a t a . Cercaria bombayensis no.19. Cercaria elvae. Cercaria gigantea. This group i s characterized by the presence of s i x pairs of flame c e l l s i n the body and by 8 3 . t h e number o f p e n e t r a t i o n g l a n d s . T h e " o c e l l a t a g r o u p " , a s c o n s t r u c t e d by S e w e l l ( l 9 2 2 ) , i s t y p e d by C e r c a r i a o c e l l a t a . The e x c r e t o r y s y s t e m o f t h i s c e r c a r i a was u n k n o w n a t t h e t i m e t h e g r o u p was c o n s t r u c t e d by S e w e l l . T h e l a t t e r s t a t -e d t h a t t h e e x c r e t o r y p a t t e r n o f t h e " o c e l l a t a g r o u p " was 2 ( 4 + 1 ) a n d he i n c l u d e d a new c e r c a r i a d i s c o v e r e d by h i m s e l f , C e r c a r i a i n d i c a e XXV. w i t h i n t h i s g r o u p . T h i s c e r c a r i a p o s -s e s s e s a n e x c r e t o r y p a t t e r n 2 ( 3 + / l + ± / ) . T h e b o d y i s d e s -c r i b e d a s b e i n g p e a r i s h a p e d , b e i n g w i d e s t a t t h e p o s t e r i o r e n d . T h e p e n e t r a t i o n g l a n d s w e r e g i v e n a s c o n s i s t i n g o f two a n t e r i o r p a i r s p l u s a l a r g e a m o r p h o u s mass p o s t e r i o r t o t h e v e n t r a l s u c k e r w h i c h was c o n s i d e r e d t o be p o s s i b l y o t h e r p e n -e t r a t i o n g l a n d s . T h e t a i l - s t e m was d e s c r i b e d a s b e i n g j o i n -ed t o t h e b o d y d i s t i n c t l y v e n t r o - p o s t e r i o r l y . The f u r c a e w e r e q u i t e s h o r t a n d t h e t a i l - s t e m was n e a r l y t w i c e t h e l e n g t h o f t h e b o d y . S e w e l l a l s o s t a t e d t h a t t h e c e r c a r i a e o f t h i s g r o u p d i f f e r " f r o m n e a r l y a l l o t h e r c l o s e l y r e l a t e d f o r m s " i n t h a t t h e p e n e t r a t i o n g l a n d d u c t s o p e n t h r o u g h p a p i l l a e a t t h e a n t -e r i o r e n d o f t h e b o d y i n s t e a d o f o p e n i n g t h r o u g h c o n i c a l h o l -l o w s p i n e s . Many a d d i t i o n s h a v e b e e n made t o t h e a b o v e g r o u p s s i n c e 1 9 2 6 . G r o u p D h a s r e c e i v e d t h e g r e a t e s t number o f a d -d i t i o n s w i t h t h e i n c r e a s i n g n u m b e r o f k n o w n S c h i s t o s o m e d e r m -a t i t i s p r o d u c e r s , a n d o t h e r s . G r o u p C , t h e " d o u t h i t t i g r o u p " , h a s r e c e i v e d a f e w a d d i t i o n s , a l s o d e r m a t i t i s - p r o d u c e r s . A s f a r a s c a n be d e t e r m i n e d G r o u p B h a s r e c e i v e d b u t two a d d i t i o n s t o t h o s e l i s t e d by M i l l e r . T h e s e a r e t h e c e r c a r i a o f G . h u r -o n e n s i s N a j i m a n d C e r c a r i a e l a n d s i a e P o r t e r . P o s i t i o n o f t h e C u l t u s L a k e C e r c a r i a e ; 84. C e r c a r i a 1 0 , o n t h e b a s i s o f t h e f l a m e c e l l p a t -t e r n a n d o t h e r s i m i l a r i t i e s , may be p l a c e d w i t h i n M i l l e r ' s G r o u p B , o r S e w e l l ' s " s p i n d a l i s g r o u p " . T h i s c e r c a r i a a l -t h o u g h a d e r m a t i t i s - p r o d u c e r s i m i l a r t o t h e c e r c a r i a o f S .  s p i n d a l i s d o e s n o t b e l o n g t o t h e . g e n u s S c h i s t o s o m a . T h e l a t t e r g e n u s i s c h a r a c t e r i z e d by t h e a b s e n c e o f e y e s p o t s a n d t h e s e s t r u c t u r e s a r e p r e s e n t o n C e r c a r i . a 1 0 . I n f a c t , t h e v e r y c l o s e s i m i l a r i t y b e t w e e n t h e c e r c a r i a o f G i g a n t o b i l h a r z i a  h u r o n e n s i s a n d C e r c a r i a 10 c o n s t i t u t e s s t r o n g e v i d e n c e i n f a v o r o f t h e a s s i g n m e n t o f t h e l a t t e r t o t h i s g e n u s . N o t h i n g f u r t h e r may be s a i d c o n c e r n i n g t h e c l a s s i f i c a t i o n o f C e r c a r i a  10 u n t i l t h e a d u l t o f t h i s f o r m i s k n o w n . C e r c a r i a c h i l l i v j a c k e n s i s p o s s e s s e s f i v e p a i r s o f f l a m e c e l l s i n t h e b o d y a n d t h e r e f o r e may be l o c a t e d i n t h e " d o u t h i t t i g r o u p " , o r G r o u p C o f M i l l e r . The c e r c a r i a o f T r i cho b i l h a r z i a a d a m s i b e l o n g s t o t h e g e n u s w h i c h i s i n c l u d e d i n G r o u p D . The c e r c a r i a e o f t h e known s p e c i e s o f T r i c h o b i l h a r z i a a l l b e l o n g t o t h e " o c e l l a t a g r o u p " . E C O L O G I C A L R E L A T I O N S H I P S OP THE THREE TREMATODES 85. P l a t e I X i l l u s t r a t e s t h e r e l a t i v e p o s i t i o n o f t h e c o l l e c t i n g a r e a ( C 1 6 ) t o o t h e r p o i n t s a t C u l t u s L a k e . T h e map ( P l a t e X) o f t h e s p e c i f i c a r e a u n d e r i n v e s t i g a t i o n shows t h e r e l a t i v e p o s i t i o n s o f t h e t h r e e a r e a s f r o m w h i c h s n a i l s w e r e c o l l e c t e d t h a t p r o d u c e d t h e c e r c a r i a e d e s c r i b e d i n t h i s w o r k . T h e s e a r e a s a l l c o n s i s t o f a f a i r l y s h . a l l o w b e a c h w h i c h i s s i m i l a r i n n a t u r e t h r o u g h o u t . T h e b o t t o m i s c o m -p o s e d o f r o c k s w h i c h i n p l a c e s a r e c o v e r e d w i t h a l i g h t g r o w t h o f a l g a e . S n a i l s w e r e g a t h e r e d i n w a t e r n o t e x c e e d i n g a n a r m ' s l e n g t h i n d e p t h . The s n a i l s f r o m t h e s e s e p a r a t e l o c -a l i t i e s , h a v e a l l b e e n i d e n t i f i e d a s b e l o n g i n g t o t h e same s p e c i e s . H o w e v e r , d e s p i t e t h e a p p a r e n t u n i f o r m i t y o f c o n d i -t i o n s t h e o c c u r r e n c e o f t h e c e r c a r i a e d e s c r i b e d was c o n f i n e d t o s p e c i f i c a r e a s . I t must be n o t e d h e r e t h a t c o l l e c t i o n s o f s n a i l s w e r e o n l y o c c a s i o n a l l y made o u t s i d e o f t h e a r e a s i n d i c a t e d a n d c e r c a r i a e c o u l d q u i t e c o n c e i v a b l y h a v e o c c u r r e d o u t s i d e o f t h e b o u n d a r i e s o f t h e a r e a s . T h e s e b o u n d a r i e s c a n n o t be p r e c i s e l y l o c a t e d a b o u t a n y g i v e n a r e a a n d t h e y a r e shown m e r e l y i n a n a t t e m p t t o d e l i m i t somewhat t h e a r e a i n q u e s t i o n . The c e r c a r i a e w e r e f o u n d t o be s p e c i f i c f o r a g i v e n a r e a a n d o n l y i n o n e c a s e , n e a r P o i n t a l p h a , d i d t h e s p e c i f i c a r e a s o v e r l a p . C e r c a r i a 1 0 was f o u n d i n A r e a B a n d i n A r e a A o n J u l y 4 a n d J u l y 29 r e s p e c t i v e l y . T h e c o n c e n t r a t i o n o f t h e s e was t h r e e t i m e s a s g r e a t i n A r e a B ( J u l y 4) a s i n A r e a A ( J u l y 2 9 ) . C e r c a r i a c h i l l i w a c k e n s i s was f o u n d i n A r e a A f a r t h e r n o r t h o n J u l y 4 , a n d i n t h e A r e a " s o u t h e n d o f b e a c h " o n J u l y 1 7 . L a t e r i n t h e summer , o n A u g u s t 3 , t h e c e r c a r i a o f T . a d a m s i was f o u n d i n A r e a B . T h a t i s , t h e l a t t e r c e r c a r i a 8 6 . seemed t o h a v e r e p l a c e d C e r c a r i a 10 i n t h i s a r e a , a l m o s t a m o n t h a f t e r C e r c a r i a 10 was f o u n d h e r e . I t i s t o be empha -s i z e d t h a t a t no t i m e were t h e a b o v e t h r e e t y p e s o f c e r c a r -i a e f o u n d i n s n a i l s w h i c h h a d b e e n l o c a t e d i n c l o s e p r o x i m i t y . F o r a n e x p l a n a t i o n o f t h i s p h e n o m e n o n i t w i l l be n e c e s s a r y t o c o n s i d e r t h e a d u l t h o s t s o f t h e T r e m a t o d e s . O f t h e t h r e e f o r m s d e s c r i b e d i n t h i s w o r k a h o s t h a s b e e n f o u n d f o r o n l y one o f t h e m , t h e c e r c a r i a o f T . a d a m s i . T h i s was e x -p e r i m e n t a l l y d e t e r m i n e d t o be a w a t e r f o w l . I t may be s u s p e c -t e d t h e n , t h a t a w a t e r f o w l i s a c t i n g a s t h e a d u l t h o s t o f t h e p a r a s i t e a t C u l t u s L a k e . S i n c e t h e c e r c a r i a h a s b e e n f o u n d o n l y i n A r e a B i t i s l i k e w i s e r e a s o n a b l e -to s u s p e c t t h a t t h e s e w a t e r f o w l i n h a b i t t h e r e g i o n o f t h e s h o r e l i n e o f A r e a B . L a r g e n u m b e r s o f w a t e r f o w l h a v e b e e n o b s e r v e d d u r i n g t h e d a y f a r o u t t o w a r d t h e m i d d l e o f t h e l a k e . None h a v e e v e r b e e n s e e n by t h i s w o r k e r a c t u a l l y c l o s e t o A r e a B d u r i n g h i s d a y t i m e v i s i t s . I t i s p e r h a p s c o n c e i v a b l e t h a t t h e b i r d s come i n t o "the a r e a d u r i n g t h e n i g h t . H o w e v e r , no r e a s o n i s s u g g e s t e d a s t o why t h e b i r d s w o u l d c h o o s e t h i s p a r t i c u l a r l o c a t i o n . A s t u d y o f t h e h a b i t s o f t h e b i r d s s e e n d u r i n g t h e d a y i s n e e d e d a n d A r e a B s h o u l d be c l o s e l y w a t c h e d a t n i g h t i n o r d e r t o d e t e r m i n e w h e t h e r t h e b i r d s a c t u a l l y do come t o t h i s r e g i o n a t t h a t t i m e . The r e m a i n i n g two c e r c a r i a e f o u n d a t a n e a r l i e r d a t e t h a n t h e a b o v e p o s s e s s a f l a m e c e l l p a t t e r n p e r h a p s i n d i c a t -i v e o f m a m m a l i a n f o r m s , b u t t h e p o s s i b i l i t y o f a n a v i a n h o s t a l s o e x i s t s . S i n c e t h e l i f e - c y c l e o f C e r c a r i a c h i l l i w a c k e n -s i s a n d t h a t o f C e r c a r i a 10 i s n o t k n o w n we c a n s a y n o t h i n g f a c t u a l c o n c e r n i n g t h e e c o l o g y o f t h e s e p a r a s i t e s . T h e c l o s e s i m i l a r i t y b e t w e e n C e r c a r i a 10 a n d t h e c e r c a r i a o f G . h u r o n -87. ensis Najim seems to indicate that t h i s c e r c a r i a i s an •avian form. It must be noted that Cercaria 10 was replaced l a t e r i n the season by an avian parasite, T.adamsi, which proves that birds capable of harboring the Trematodes are either present or do v i s i t the v i c i n i t y of thi s region. How-ever, Cercaria 10 i s also similar to the cercari a of S.spin-d a l i s which matures i n the buffalo of Malaya. An important question i n the consideration of l i f e -cycles i s chronology. We can delimit the period of existence of the cercaria to a few hours, or possibly days, aft e r i t has emerged. It therefore follower that penetration of the cercaria into the d e f i n i t i v e host occurs during t h i s time. In the case of Tr i c h o b i l h a r z i a adamsi the adult worm becomes mature i n approximately 50 days from the time of exposure of the host, under laboratory conditions. With other forms there may be a va r i a t i o n within approximately 20 days on either side of thi s f i g u r e . When the worm reaches maturity eggs are deposited i f i t i s a female and these reach the wa-ter with the host faeces. It may take approximately three or four days for the eggs themselves to become f u l l y mature before they are released by the female(Price,193l). The egg gives fort h a miracidium which may be free-swimming for a very short time (similar to the cercariae), and thi s pene-trates a s n a i l . Cercariae usually emerge from the s n a i l from approximately 50 days after the mollusc has become infected. The above developmental times have been determined i n the laboratory i n the past iby many workers. However, under natural conditions i n the f i e l d the l i f e - c y c l e s are not so d i r e c t . I f we begin the cycle i n the case of T.adamsi with the free-swimming cercaria on August 4, 8 8 . on the basis of the above chronology the adult would be ma-ture on approximately September 2 3 and miracidia would hatch three days l a t e r . The l a t t e r would inf e c t snails and the cercariae, according to laboratory data of other workers, would escape on approximately November 15. This i s not the case. Dermatitis-producing cercariae are found annually and t h e i r periods of emergence vary only s l i g h t l y from year to year. It i s obvious then that the cycle i s retarded at some point. It remains no?; to consider the possible points of re-tardation. The l i f e - c y c l e of the Trematodes could be slowed down at two points: (l.-development of the adult i n the d e f i n i t i v e host. (2.-development' of the sporocysts and cercariae within the s n a i l intermediate host. If the maturation of the adults i n the d e f i n i t i v e host i s retarded the snails w i l l become infected with miracid-i a during the spring, the adults "wintering" i n the d e f i n i -t i v e host. Now, i f the s n a i l i s to be infected i n the spring and i f normal development of the sporocysts and cercariae i s to occur, the miracidia w i l l have to penetrate the s n a i l near the f i r s t part of June. This would allow the cercariae to emerge at the time at which they have been observed (Ju l y ) . It i s possible that the snails become infected e a r l i e r than June and a certain amount of retardation of development occurs i n the s n a i l , to allow the cercariae to escape l a t e r i n the summer. If the l a r v a l development of the Trematodes i s re-89. tarded i n the intermediate host stage of the l i f e - c y c l e , the snails must become infected i n the P a l l . The i n f e c t i o n would be carried over the winter i n the s n a i l host. However, a l l of the snails found to be infected with dermatitis-producing Schistosomes during the present investigations were snails which had not been carried over from the previous year. They had a l l hatched during the spring of the same year that they were found giving off cercariae. It i s therefore obvious that they must have become infected at some time during the spring, p r i o r to the f i r s t week of June. PLATE IX '. uontour map i n g the r e l a t i v e CI6 to important of Cultus Lake, p o s i t i o n of the landmarks. B.C. i l l u s t r a t -c o l l e c t i n g area PLATEIS PLATE X enlargement of square C16 shown i n P l a t e IX i l l u s t r a t i n g r e l a t i v e p o s i t i o n s of s p e c i f i c c o l -l e c t i n g areas. C e r c a r i a 10; spacing i n d i c a t e s c o n c e n t r a t i o n of i n f e c t i o n . C e r c a r i a of T.adamsi. CercasEia c h i l l i w a c k e n s i s . CULTUS LAKE M A L L A R D POINT PLATE X: 9 0 . S C H I S T O S O M E - D E R M A T I T I S E X P E R I M E N T S . T h e c e r c a r i a o f T r i c h o b i l h a r z i a a d a m s i , C e r c a r i a 1 0 , C e r c a r i a c h i l l i w a c k e n s i s a n d C e r c a r i a 1 6 A w e r e i n v e s t i g a t e d e x p e r i m e n t a l l y t o d e t e r m i n e t h e i r a b i l i t y t o p r o d u c e S c h i s t o -some d e r m a t i t i s . A l l w e r e f o u n d t o be d e r m a t i t i s - p r o d u c e r s . A d e s c r i p t i o n i s g i v e n b e l o w o f t h e p r o c e d u r e u s e d t o d e t e r -m i n e t h i s c h a r a c t e r i s t i c o f t h e v a r i o u s t y p e s o f c e r c a r i a e . The C e r c a r i a o f T . a d a m s i . On A u g u s t 4 , 1 9 5 3 , a f e w d r o p s o f w a t e r c o n t a i n i n g c e r c a r i a e w e r e a p p l i e d w i t h a d r o p p e r t o t h e f l e x o r s u r f a c e o f t h e a u t h o r ' s r i g h t a r m . W i t h i n f i v e m i n u t e s a p r i c k l i n g was f e l t o n t h i s a r e a w h i c h g r a d u a l l y i n c r e a s e d i n i n t e n s i t y . A t t h i s t i m e t h e a r e a o n t h e s u r f a c e o f t h e a r m was r u b b e d v i g o r o u s l y w i t h t h e p a l m o f t h e l e f t h a n d a n d t h e " i t c h i n g " s u b s i d e d . One d a y l a t e r no m a c u l e s w e r e p r e s e n t . T h e same c e r c a r i a e w e r e a p p l i e d t o t h e l e f t a r m o f a woman c o - w o r k e r a n d s h e f e l t a n i n t e n s e i t c h i n g w i t h i n a f e w m i n u t e s . One d a y l a t e r e i g h t s m a l l p a p u l e s w e r e p r e s e n t o n t h i s r e g i o n o f h e r a r m . T h i s woman i n t h e p a s t h a d a l w a y s s h o w n a v e r y m a r k e d r e a c t i o n t o d e r m a t i t i s - p r o d u c i n g c e r c a r i a e . * * I h a d d i t i o n s e e E x p e r i m e n t s w i t h " F e n d - E " . C e r c a r i a 1 6 A . On S e p t e m b e r 4 a f e w d r o p s o f w a t e r c o n t a i n i n g t h e s e c e r c a r i a e w e r e a p p l i e d t o t h e f l e x o r s u r f a c e o f t h e a u t h o r ' s l e f t f o r e a r m . The e x p o s e d r e g i o n was h e l d n e a r a l i g h t . W i t h i n t e n m i n u t e s a n i n t e n s e p r i c k l i n g s e n s a t i o n was f e l t 9 1 . w h i c h l a s t e d a f e w m i n u t e s . The n e x t d a y a l a r g e r e d , r a i s e d a r e a p l u s two r e d p a p u l e s w e r e p r e s e n t o n t h i s r e g i o n a n d t h e s e i t c h e d when r u b b e d l i g h t l y , i n a manne r s u g g e s t i v e o f m o s q u i t o b i t e s . P o u r d a y s a f t e r e x p o s u r e t h e p a p u l e s a n d r a i s -ed p o r t i o n h a d s u b s i d e d l e a v i n g o n l y a s l i g h t p i g m e n t a t i o n a n d e l e v a t i o n o f t h e s k i n . C e r c a r i a 1 0 . A f e w d r o p s o f w a t e r c o n t a i n i n g c e r c a r i a e w e r e a p p l i -e d t o t h e f l e x o r s u r f a c e o f t h e a u t h o r ' s l e f t f o r e a r m . Two s u c h a t t e m p t s w e r e made t o p r o d u c e a r e a c t i o n b u t n e i t h e r r e -s u l t e d i n a n y r e a c t i o n w h a t e v e r . T h e c e r c a r i a e w e r e t h e n a p -p l i e d t o t h e f o r e a r m o f t h e c o - w o r k e r m e n t i o n e d a b o v e . . W i t h i n a f e w m i n u t e s s h e r e p o r t e d a p r i c k l i n g s e n s a t i o n w h i c h i n -c r e a s e d i n i n t e n s i t y . A t t h i s p o i n t s h e r u b b e d t h e a r e a v i g o r -o u s l y w i t h f o r m a l i n a n d no f u r t h e r r e a c t i o n was n o t e d . L a t e r , some d r o p s o f w a t e r c o n t a i n i n g t h e s e c e r c a r i a e w e r e a p p l i e d t o t h e a u t h o r ' s r i g h t f o r e a r m a n d w i t h i n f i v e m i n u t e s a s e v e r e p r i c k l i n g s e n s a t i o n was f e l t w h i c h g r e w i n i n t e n s i t y . I h r e e h o u r s l a t e r a t l e a s t f o u r m a c u l e s w e r e a p -p a r e n t o n t h a t r e g i o n o f t h e f o r e a r m . S i m u l t a n e o u s l y , t h e c e r c a r i a e w e r e a p p l i e d t o t h e f o r e a r m o f t h e a u t h o r ' s c o - w o r k -e r . A n i t c h r e s u l t e d w h i c h , two h o u r s l a t e r , r e s u l t e d i n t h e f o r m a t i o n o f two p a p u l e s . One o f t h e s n a i l s g i v i n g o f f C e r c a r i a 10 was d i s s e c t -e d a n d some o f t h e c e r c a r i a e t h u s o b t a i n e d w e r e a p p l i e d t o t h e r i g h t f o r e a r m o f t h e a u t h o r . ? / i t h i n t e n m i n u t e s a p r i c k l i n g was f e l t a n d w i t h i n one h o u r t h r e e m a c u l e s w e r e o b s e r v e d o n t h i s a r e a . A n o c c a s i o n a l p r i c k l i n g was s t i l l n o t i c e a b l e a f e w h o u r s a f t e r a p p l i c a t i o n o f t h e c e r c a r i a e . i t i s c u r i o u s t o n o t e t h a t a d e r m a t i t i s was n o t p r o -d u c e d o n t h e a u t h o r ' s l e f t a r m i n t h e f i r s t e x p e r i m e n t w i t h t h i s c e r c a r i a w h i l e l a t e r , u s i n g e x a c t l y t h e same m e t h o d , t h e r e a c t i o n was p r o d u c e d c o n s i s t a n t l y o n t h e o t h e r a r m . T w e l v e d a y s a f t e r t h e a b o v e e x p e r i m e n t s w i t h t h e c e r c a r i a h a d b e e n p e r f o r m e d a f e w s m a l l r a i s e d p o r t i o n s w h i c h were n o t p i g m e n t e d w e r e p r e s e n t o n t h e f l e x o r s u r f a c e o f t h e a u t h o r ' s r i g h t f o r e a r m . T h e s e d i d n o t p r o d u c e a n i r r i t a t i o n a t t h i s t i m e . C e r c a r i a c h i l l i w a c k e n s i s . T h e a b i l i t y o f t h i s c e r c a r i a t o p r o d u c e a d e r m a t i t i s was i n v e s t i g a t e d by a p p l y i n g a number o f t h e c e r c a r i a e i n a d r o p o r two o f w a t e r t o t h e f l e x o r s u r f a c e o f t h e f o r e a r m o f t h e a u t h o r a n d t h e a u t h o r ' s c o - w o r k e r . T h e c e r c a r i a e p r o d u c e d a f a i r l y i n t e n s e i t c h i n g o n t h e c o - w o r k e r ' s a r m , f o l l o w e d by two p a p u l e s w h i c h l a s t e d f o r a p p r o x i m a t e l y t e n d a y s . T h e c e r c a r i a e o n t h e a u t h o r ' s a r m p r o d u c e d a f a i r l y i n t e n s e i t c h -i n g when t h e w a t e r h a d n e a r l y c o m p l e t e l y d r i e d . Two p a p u l e s f o l l o w e d w h i c h l a s t e d w e l l o v e r t h r e e w e e k s . E x p e r i m e n t s W i t h w P e n d - E " . T h i s s u b s t a n c e , w h i c h i s s o l d a s a d i r t r e p e l l e n t • f o r m i n e r s , , was i n v e s t i g a t e d t o d e t e r m i n e w h e t h e r i t w o u l d i n h i b i t p e n e t r a t i o n o f t h e d e r m a t i t i s - p r o d u c i n g c e r c a r i a e . I t was f o u n d t o be c a p a b l e o f p r e v e n t i n g a d e r m a t i t i s when t h e c e r c a r i a o f T . a d a m s i was a p p l i e d t o t h e r e g i o n o f t h e 93. a r m w h i c h h a d b e e n c o a t e d w i t h i t . H o w e v e r , i t was d i s c o v -e r e d t h a t t h e s u b s t a n c e w o u l d w a s h o f f i n r u n n i n g t a p - w a t e r . T h u s , i t was c o n s i d e r e d i m p r a c t i c a l f o r u s e a s a S c h i s t o s o m e d e r m a t i t i s p r e v e n t a t i v e . I t was l a t e r l e a r n e d t h a t t h e r e e x i s t s a s i m i l a r r e p e l l e n t o n t h e m a r k e t , " F e n d - I n , w h i c h i s i n s o l u b l e i n w a t e r , a n d f u t u r e e x p e r i m e n t a t i o n w i t h t h i s s u b -s t a n c e may p r o v e f r u i t f u l . 94. D I S C U S S I O N . A s h a s b e e n p r e v i o u s l y m e n t i o n e d , a n u n d e s c r i b e d c e r c a r i a was d i s c o v e r e d a t C u l t u s L a k e i n 1 9 5 1 , a n d t h i s l e d t o t h e p r e s e n t i n v e s t i g a t i o n . I t i s n e c e s s a r y t o c o n s i d e r a t t h i s t i m e t h e p o s s i b l e r e a s o n s f o r t h e c e r c a r i a h a v i n g f a i l -e d t o t u r n up d u r i n g t h e c o u r s e o f t h e r e c e n t w o r k . T h r e e p o s s i b i l i t i e s e x i s t f o r t h e e x p l a n a t i o n o f t h e s i t u a t i o n * ( l . - D u e t o r a n d o m s e l e c t i o n o f t h e s n a i l s c o l l e c t e d i n t h e a r e a s , s n a i l s h a r b o r i n g t h e c e r c a r i a . w e r e by c h a n c e m i s s e d . ( 2 . - T h e 1 9 5 1 c e r c a r i a was r e s t r i c t e d t o a s m a l l a r e a . T h i s a r e a was n o t d e s c r i b e d s p e c i f i c a l l y by p r e -v i o u s w o r k e r s a n d t h e 1 9 5 3 c o l l e c t i o n s f a i l e d t o s a m p l e t h e a r e a . ( 3 . - T h e c e r c a r i a was e r r o n e o u s l y d e s c r i b e d , t h e d e s -c r i p t i o n c o n s i s t i n g i n r e a l i t y o f a c o m p o s i t e o f two o r more o f t h e c e r c a r i a e d e s c r i b e d i n t h e p r e s e n t w o r k . T h e f i r s t two p o s s i b l e e x p l a n a t i o n s i n f e r t h a t t h e c e r c a r i a p r e v i o u s l y d e s c r i b e d d o e s i n f a c t e x i s t . I f t h e f i r s t p o s s i b i l i t y o u t l i n e d a b o v e i s t r u e , t h e n c e r t a i n l y i n -f e c t i o n s o f s n a i l s by t h i s c e r c a r i a a r e e x t r e m e l y s c a r c e , more so e v e n t h a n w e r e t h e i n f e c t i o n s d e s c r i b e d a t t h e p r e s e n t t i m e . H o w e v e r , S.M . S a g e r i n h i s i n v e s t i g a t i o n s o f t h e a r e a i n 1 9 5 1 r e p o r t e d t h e i n c i d e n c e o f i n f e c t i o n o f t h i s c e r c a r i a a t t h a t t i m e t o be o f t h e o r d e r o f 6%, a f i g u r e w h i c h i s much i n e x c e s s o f t h e r e s u l t s o f t h e p r e s e n t i n v e s t i g a t i o n . 9 5 . T h e s e c o n d - p o s s i b i l i t y i s p e r h a p s more r e a s o n a b l e , t h e a c c o u n t s o f t h e d i s c o v e r y o f t h e u n k n o w n c e r c a r i a o f 1 9 5 1 s t a t e t h a t i t was f o u n d i n C 1 6 , t h e a r e a " i n t o t o " i n w h i c h t h e p r e s e n t i n v e s t i g a t i o n s w e r e c a r r i e d o u t . No t r a c e o f d e s c r i p t i o n s o f s p e c i f i c s u b - a r e a s w h e r e t h i s c e r c a r i a was f o u n d a r e a v a i l a b l e . I n v i e w o f t h e f a c t t h a t t h e T r e m a t o d e s d e s c r i b e d i n t h e p r e s e n t w o r k w e r e f o u n d t o o c c u r i n s p e c i f -i c l i m i t e d a r e a s , i t seems p r o b a b l e t h a t t h e 1 9 5 1 c e r c a r i a c o u l d be e a s i l y m i s s e d . The s u b - a r e a s i n w h i c h t h e p r e s e n t c e r c a r i a e w e r e f o u n d i n c l u d e d a t o t a l a r e a o f no more t h a n o n e t h i r d o f t h e e n t i r e C 1 6 . A d m i t t e d l y , s n a i l s w e r e c o l l e c t -e d f r o m mos t o f t h e e n t i r e a r e a i n q u e s t i o n , b u t t h o s e c o l l e c t -e d f r o m r e g i o n s n o r t h o f t h e " S o u t h e n d o f b e a c h " a r e a w e r e f o r t h e mos t p a r t j u v e n i l e s a n d n e v e r g a v e o f f c e r c a r i a e o f a n y t y p e . T h e t h i r d a n d l a s t p o s s i b l e e x p l a n a t i o n f o r t h e a b -s e n c e o f t h e 1 9 5 1 c e r c a r i a i n f e r s t h a t t h e c e r c a r i a a s d e s -c r i b e d by t h e o t h e r w o r k e r s d o e s n o t e x i s t . T h i s w o u l d mean e i t h e r t h a t some o t h e r c e r c a r i a ( p o s s i b l y o n e o f t h e t h r e e d e s c r i b e d i n t h e p r e s e n t w o r k ) was i n c o r r e c t l y d e s c r i b e d , o r t h a t t h e d e s c r i p t i o n p u t f o r t h was a c t u a l l y a c o m p o s i t e .of two o r more d i f f e r e n t f o r m s . T h e ' o n l y p o s s i b l e e x p l a n a t i o n f o r t h i s l a t t e r o x u r r i n g , t o t h e a u t h o r ' s m i n d , i s t h a t t h e g r e a t amount o f e m p h a s i s p u t u p o n t h e p o s s e s s i o n o f p a p i l l a r s p i n a t i o n by t h i s f i r s t c e r c a r i a may h a v e l e d t o t h e c o n c l u -s i o n . t h a t o n l y one s p e c i e s was b e i n g d e a l t w i t h . H o w e v e r , t h e c e r c a r i a e d e s c r i b e d a t t h e p r e s e n t t i m e do n o t a p p e a r c l o s e -l y s i m i l a r m o r p h o l o g i c a l l y , e v e n a t f i r s t g l a n c e . I t seems u n l i k e l y t h a t t h e p r e v i o u s w o r k e r s w o u l d m i s t a k e t h e m f o r a s i n g l e s p e c i e s . 96. U p o n c o n s i d e r a t i o n o f a l l t h e f a c t o r s i n v o l v e d , i t seems mos t p r o b a b l e t h a t e i t h e r t h e f i r s t o r s e c o n d o f t h e p o s s i b l e e x p l a n a t i o n s o u t l i n e d a b o v e e x p l a i n s t h e f a i l u r e t o u n c o v e r , t h e 1951 c e r c a r i a d u r i n g t h e s u m m e r - o f 1953. I n o t h e r w o r d s , i n t h e a u t h o r ' s o o p i n i o n , i t i s h i g h l y l i k e l y t h a t t h e c e r c a r i a d e s c r i b e d a s b e i n g t e n t a t i v e l y new i n 1951 s t i l l e x i s t s a s s u c h a n d h a s n o t b e e n f o u n d a g a i n . C o n t i n u e d i n v e s t i g a t i o n s o f t h e t y p e s o f S c h i s t o s o m e c e r c a r i a e p r e s e n t i n t h e a r e a i n q u e s t i o n s h o u l d be made i n s u c c e e d i n g y e a r s a n d t h e 1951 c e r c a r i a s h o u l d n o t be c o n s i d e r e d n o n - e x i s t a n t w i t h a n y d e g r e e o f c e r t a i n t y u n t i l two more s u c h i n v e s t i g a -t i o n s r e p r e s e n t i n g two summers w o r k h a v e f a i l e d t o r e v e a l i t . 97. SUMMARY. T h r e e d e r m a t i t i s - p r o d u c i n g c e r c a r i a e , d i s c o v e r e d a t C u l t u s L a k e d u r i n g t h e summer o f 1 9 5 3 , h a v e b e e n d e s c r i b e d . I n a d d i t i o n r e f e r e n c e h a s b e e n made t o t h e e x i s t e n c e o f a n -o t h e r v e r y s i m i l a r c e r c a r i a i n t h i s r e g i o n . Two o f t h e T r e m - -a t o d e s a r e d e s c r i b e d a s new s p e c i e s , w h i l e two may be n e w . T h e p o s i t i o n o f t h e l a t t e r i s l e f t o p e n t o q u e s t i o n due t o a l a c k o f d e s c r i p t i o n o f t h e a d u l t s . A t t e m p t s w e r e made t o d i s c o v e r t h e l i f e - c y c l e o f e a c h o f t h e t h r e e T r e m a t o d e s . I n i t i a l l y o n l y t h e c e r c a r i a l s t a g e was k n o w n . Two a p p r o a c h e s w e r e a d o p t e d . A n i m a l s w e r e t r a p p e d i n t h e f i e l d a n d e x a m i n e d f o r a d u l t S c h i s t o s o m e s ; a n d l a b o r a t o r y a n i m a l s w e r e e x p o s e d t o t h e c e r c a r i a e i n a t t e m p t s t o i n f e c t t h e m . A l l e x a m i n a t i o n s o f a n i m a l s f r o m t h e f i e l d p r o v e d t o be n e g a t i v e . The m a j o r p o r t i o n o f t h e l i f e - c y c l e o f o n e o f t h e c e r c a r i a e was e s t a b l i s h e d e x p e r i m e n t a l l y a n d t h e T r e m a t o d e . , , d e s c r i b e d a s a new s p e c i e s , h a s b e e n named T r i c h o b i l h a r z i a  a d a m s i . I n t h e . l a b o r a t o r y two P e k i n d u c k l i n g s w e r e e x p o s e d t o t h e c e r c a r i a o f T . a d a m s i a n d l a t e r o n e i m m a t u r e a d u l t f e -m a l e was r e m o v e d f r o m t h e l i v e r o f o n e o f t h e m . E s t a b l i s h e d i n t h i s l i f e - c y c l e a t p r e s e n t a r e t h e f e m a l e a d u l t , s p o r o c y s t a n d c e r c a r i a , a s w e l l a s t h e two h o s t s i n v o l v e d ( t h e n a t u r a l a d u l t h o s t h a s n o t b e e n d e t e r m i n e d ) , T r i c h o b i l h a r z i a a d a m s i i s a member o f t h e " o c e l l a t a g r o u p " . C e r c a r i a c h i l l i w a c k e n s i s , d i a g n o s e d a s a new s p e c i e s , was e x p o s e d i n t h e l a b o r a t o r y t o w h i t e m i c e , p i g e o n s a n d one P e k i n d u c k l i n g . L a t e r e x a m i n a t i o n p r o v e d t h a t no c e r c a r i a e -h a d p e n e t r a t e d a n d r e a c h e d t h e a d u l t s t a g e . C e r c a r i a c h i l l i -98. wackensis i s a member of the " d o u t h i t t i group" and appears very s i m i l a r to C.tuckerensis M i l l e r 1927. C e r c a r i a 10 was exposed to white mice, one Guinea p i g and two Pekin d u c k l i n g s . A l l animals were found to be negative when l a t e r examined f o r the presence of the a d u l t worm. C e r c a r i a 10 i s a member of the " s p i n d a l i s group" and i s very s i m i l a r , i f not i d e n t i c a l with, the c e r c a r i a of G i -g a n t o b i l h a r z i a huronensis Najim 1951. No d e f i n i t e determin-a t i o n of the p o s i t i o n of C e r c a r i a 10 could be made. I t was t h e r e f o r e deemed a d v i s a b l e to leave the matter open u n t i l the a d u l t i s known and f u r t h e r comparisons can be made. A l l three c e r c a r i a e , C e r c a r i a 10, C e r c a r i a c h i l l i -Yfackensis and the c e r c a r i a of T.adamsi possess a type of s p i n -a t i o n which i s d i s t i n c t from the usual type of small s p i n a - . t i b n found on the body of Schistosome c e r c a r i a e . T h i s has been c a l l e d " p a p i l l a r s p i n a t i o n " and has been p r e v i o u s l y d e s c r i b e d only by Najim(l95l) on non-human d e r m a t i t i s - p r o d -ucing Schistosome c e r c a r i a e . The spines have been found very i n f r e q u e n t l y by c e r t a i n other workers on some of the other Schistosomes. A d e s c r i p t i o n of t h i s s p i n a t i o n has been g i v e n i n the present work. Two important phenomena were d i s c o v e r -ed with r e l a t i o n to the occurrence of the p a p i l l a r spines on the Cultus Lake Trematodes. The p a p i l l a r spines are present i n a very s i m i l a r p a t t e r n on the body of a l l of the c e r c a r i a e d e s c r i b e d . Further, i t was e s t a b l i s h e d that the s p i n a t i o n i s c a r r i e d through from the c e r c a r i a to the a d u l t of T.adamsi and f o r the most p a r t , the l o c a t i o n p a t t e r n i s maintained i n the>adult. As f a r as can be determined, t h i s represents the f i r s t time that p a p i l l a r s p i n a t i o n has been d e s c r i b e d as oc-c u r r i n g on an a d u l t Schistosome. 9 9 . Ecological studies of the s n a i l hosts of Cercaria  10, Cercaria chilliwackensis and the cercaria of T.adamsi revealed that the snails giving o f f the individual types of cercariae were confined to s p e c i f i c areas. Only i n one i n -stance did these overlap. In this case the occurrence of Cercaria 10 was replaced l a t e r i n the season by the cercaria of T.adamsi. It i s believed that the i n f e c t i o n of the s n a i l intermediate hosts of the Trematodes occurs at some time during the spring, p r i o r to June. An outline has been given of the methods adopted i n determining the dermatitis-producing cha r a c t e r i s t i c s of the Cultus Lake cercariae described i n this work. A modification of the perfusion technique of Yolles et a l , i s described. This was used i n attempts to recover any adult Schistosomes which might have been present i n the experimental white mice. The reasons for the adoption of these modifications are given. They enabled the. author to perform the necessary perfusions of the l i v e r s while at the same time maintaining a constant pressure i n the perfusion apparatus. The l a t t e r was necessary since no source of con-stant air-pressure was available and a hand-bulb had to be used. A new technique has been described for concentrating large numbers of Schistosome cercariae when the number a v a i l -able through ordinary means i s li m i t e d . This technique i n -volves the use of a side-arm f l a s k and u t i l i z e s the taxes of the cercariae. Cercaria 1 0 , which i s especially responsive to a l i g h t stimulus, could be concentrated i n extremely large numbers i n the side-arm of the f l a s k . LITERATURE CITED 100. Brackett,S. 1942: Five new species of avian schistosomes from Wisconsin and Michigan with the l i f e - c y c l e of G i g a n t o b i l h a r z i a g y r a u l i (Brackett,1940). J . P a r a s i t , 28(1): 25 - 42 Buckley, J.J.C.1938: On a d e r m a t i t i s i n Malays caused by the ce r c a r i a e of Schistosoma spindale Mont-gomery, 1906. J . Helminthology, 16(2); 117 - 120. Chandler, A: I n t r o d u c t i o n to the ' f o r m s—Diagnosis. Introduc-t i o n to P a r a s i t o l o g y , 8th e d i t i o n , Chap.11* P. 251. Cort, W.W. 1928a: Schistosome d e r m a t i t i s i n the United s t a t e (Michigan). J . Amer.Med.Assoc. 90: 1027 -. 1029. 1928b: Further observations on Schistosome derma-t i t i s i n the United States (Michigan) . Sci-ence, 68(1764): p.388. 1936a: Studies on Schistosome' d e r m a t i t i s — 1 ; Pres ent status of the subject. Amer. Journ. of Hygiene, 23: 349- 371. 1936b: Studies on Schistosome d e r m a t i t i s — I V ; Pur. information on d i s t r i b u t i o n i n Canada and the United S t a t e s . Amer. Journ, of Hygiene 24(2): 318 - 333. Cort, W.W. and. Talbot, S.B. 1936: Studies on Schistosome d e r m a t i t i s — 1 1 1 ; Observations on the be-havior of the dermatitis-producing S c h i s t -osome d e r c a r i a e . Amer. Journ. of Hygiene, 23(2); 385 - 396. 101. • H a r p e r , W . F . 1 9 2 9 : On t h e s t r u c t u r e a n d l i f e h i s t o r y o f B r i t i s h f r e s h w a t e r l a r v a l t r e m a t o d e s . P a r a s i t . 2 1 ; 189 ' - 1 9 9 . H u n t e r , G . W . I l l , S h i l l a m , D . S . , T r o t t , C . T . , a n d H o w e l l , E . V . J r . 1 9 4 9 : S c h i s t o s o m e d e r m a t i t i s i n S e a t t l e , W a s h i n g t o n . J . P a r a s i t . 35_: 2 5 0 -2 5 4 . H u s s e y , K . L . 1 9 4 1 : C o m p a r a t i v e e m b r y o l o g i c a l d e v e l o p m e n t o f t h e e x c r e t o r y s y s t e m i n D i g e n e t i c t r e m -a t o d e s . T r a n s . A m e r . M i c . S o c . 6 0 ( 2 ) : 1 7 1 -2 1 0 . J o h n s t o n e , T . H . a n d C l e l a n d , E . R . 1 9 3 7 : L a r v a l t r e m a t o d e s f r o m A u s t r a l i a n t e r r e s t r i a l a n d f r e s h w a t e r m o l l u s c s . P a r t 1 1 — C e r c a r i a ( F u r c o c e r c a r i a ) j a e n s c h i n . s p . T r a n s . R o y . S o c . S . A u s . 6 1 : 202 - 2 0 6 . Kemp , S . 1 9 2 1 : N o t e s o n l a r v a l t r e m a t o d e s f r o m - S e i s t a n . R e c . I n d . M u s . , C a l c u t t a . 1 8 : 229 - 2 3 3 . M a c y , R . W . 1 9 5 2 : S t u d i e s o n S c h i s t o s o m e d e r m a t i t i s i n t h e P a c i f i c n o r t h w e s t . N o r t h w e s t M e d i c i n e , S e a t t l e . 5 1 ( 1 1 ) : p . 9 4 7 . M a c y , R . W . a n d M o o r e , D . J . 1 9 5 3 : The r e l a t i o n s h i p b e t w e e n T r i c h o b l l h a r z i a o r e g o n e n s i s a n d T . e l v a e , e t i o l o g i c a l a g e n t s o f S c h i s t o s o m e d e r m a -t i t i s i n t h e P a c i f i c n o r t h w e s t . S c i e n c e . 1 1 8 ( 3 0 7 4 ) : p 6 5 0 . M c L e o d , J . A . 1 9 4 0 : S t u d i e s o n c e r c a r i a l d e r m a t i t i s a n d t h e T r e m a t o d e f a m i l y S c h i s t o s o m a t i d a e i n M a n -i t o b a . C a n . J o u r n . R e s . 1 8 : 1 - 2 8 . ' 1 0 2 . M c L e o d , J . A . a n d L i t t l e , G . E . 1 9 4 2 ; C o n t i n u e d s t u d i e s o n c e r c a r i a l d e r m a t i t i s a n d t h e t r e r a -a t o d e f a m i l y S c h i s t o s o m a t i d a e i n M a n i t o b a . C a n . J o u r n ^ R e s . , 2 0 : 1 7 0 - 1 8 1 . M c M u l l e n , D . B . a n d B e a v e r , P . C . 1 9 4 5 : S t u d i e s o n S c h i s t o s o m e d e r m a t i t i s — I X ; T h e , l i f e - c y c l e s o f t h r e e d e r m a t i t i s - p r o d u c i n g S c h i s t o -somes f r o m b i r d s a n d a d i s c u s s i o n o f t h e s u b f a m i l y B i l h a r z i e l l i n a e ( T r e m -a t o d a : S c h i s t o s o m a t i d a e ) . A m e r . J o u r n . o f H y g i e n e , 4 1 - 4 2 : 128 - 1 5 4 . M i l l e r , H . M . 1 9 2 6 : C o m p a r a t i v e s t u d i e s o n F u r c o c e r c o u s c e r c -a r i a e . I l l i n o i s B i o l o g i c a l M o n o g r a p h s , 10 ( 3 ) : 2.65::- 3 7 0 . 1 9 2 7 : F u r c o c e r c o u s l a r v a l t r e m a t o d e s f r o m S a n J u a n I s l a n d , W a s h i n g t o n . P a r a s i t . , 1 9 ( 1 ) : 61 - 8 3 . N a j i m , A . T . 1 9 5 1 : L i f e h i s t o r y o f G i g a n t o b i l h a r z i a h u r o n e n -s i s N a j i m , 1 9 5 0 a d e r m a t i t i s - p r o d -u c i n g b i r d b l o o d - f l u k e ( T r e m a t o d a : S c h i s t o s o m a t i d a e ) . D o c t o r a t e t h e s i s , P u b . n o . 3 5 3 9 : A n n A r b o r , M i c h i g a n . N e u h a u s , W. 1 9 5 2 : D e r E i n f l u s s d e s Z w i s c h e n w i r t e s a u f d i e G e s t a l t d e r C e r c a r i e v o n T r i c h o b i l -h a r z i a s z i d a t i N e u h a u s , 1 9 5 1 u n d i h r e s y s t e r n a t i s c h e K e n n z e i c h n u n g . Z o o l o g i s c h e r A n z e i g e r , 1 4 8 ( 9 - 1 0 ) : 275 - 2 8 5 . 1 0 3 . O l i v i e r , L . 1 9 5 1 : The i n f l u e n c e o f l i g h t o n t h e e m e r g e n c e o f S c h i s t o s o m a t i u m d o u t h i t t i c e r c a r i a e f r o m t h e i r s n a i l h o s t . J . P a r a s i t . 3 7 : 20)1 - 2 0 4 . 1 9 5 3 : O b s e r v a t i o n s o n t h e m i g r a t i o n o f a v i a n S c h i s t o s o m e s i n mammals p r e v i o u s l y u n e x p o s e d t o c e r c a r i a e . J . P a r a s i t . 3 9 ( 3 ) : 237 - 2 4 3 . O l i v i e r , L a n d S t i r e w a l t , M . A , 1 9 5 2 : A n e f f i c i e n t m e t h o d f o r e x p o s u r e o f m i c e t o c e r c a r i a e o f S c h i s t o s o m a m a n s o n i . J . P a r a s i t . 3 8 ( 1 ) : 19 - 2 3 . P e n n e r , L . R . 1 9 4 1 : T h e p o s s i b i l i t i e s o f s y s t e m i c i n f e c t i o n w i t h d e r m a t i t i s - p r o d u c i n g S c h i s t o -s o m e s . S c i e n c e , 9 3 : 327 - 3 2 8 . 1 9 4 2 : S t u d i e s o n d e r m a t i t i s - p r o d u c i n g S c h i s t o -somes i n e a s t e r n M a s s a c h u s e t t s , w i t h e m p h a s i s o n t h e s t a t u s o f S . p a t h l o -c o p t i c u m T a n a b e , 1923 . . J . P a r a s i t . 2 8 ( 2 ) : 1 0 3 - 1 1 6 . P o r t e r , A n n i e . 1 9 3 8 : T h e l a r v a l T r e m a t o d a f o u n d i n c e r t a i n S o u t h A f r i c a n m o l l u s c a . P u b s , o f t h e S o u t h A f r i c a n I n s t i t u t e f o r M e d i c a l ' R e s e a r c h , 8 ( 5 2 ) . 492 p p . P r i c e , E . W . 1 9 2 9 : A s y n o p s i s o f t h e T r e m a t o d e f a m i l y s c h i s t o -. s o m i d a e w i t h d e s c r i p t i o n s o f new g e n e r a a n d s p e c i e s . P r o c . D . S . N a t . M u s . , 7 5 ( 1 8 ) : 1 - 3 9 . 104. Price, H.F. 1931: L i f e history of Schistosomatium do u t h i t t i Cort. Amer. Journ. of Hygiene. 13; 665 - 727. Sager, S.M. 1950: Studies on l a r v a l trematoda of Burnaby Lake, B.C. Master's thesis; University of B r i t i s h Columbia. 121 pp. Sewell, R.B.S. 1922: Cercariae indicae. Ind. Journ. Med. Res. 10 (supplement): 1 - 370. Simmonds, W.L. Martin, W.E. and Wagner, E.D. 1951: Freshwater c e r c a r i a l dermatitis from southern Cal-i f o r n i a . Amer. Journ. Trop. Med. 31(5): 611 - 613. Soparkar, M.B. 1921: The cercaria of Schistosomum spindalis Montgomery, 1906. Ind. Journ. Med. Res. 9(1): 1 - 23. Stunkard, H.N. 1929: The excretory system of Cryptocotyle (Het-erophyidae). J . Parasit. 15: 259 - 266. Talbot, S.B. 1936: Studies on Schistosome dermatitis.—11; Mor-phological and l i f e history studies on three dermatitis-producing Schistosome .cercariae, C . elvae M i l l e r , 1923, C ._ stagnicolae n.sp. a,nd C . physellae n.spp Amer. Journ. of Hygiene. 23(2): 372 -384. Tanabe, B. 1923: The l i f e history of a new Schistosome, Schisto-somatium pathlocopticum Tanabe, found i n experimentally infected mice. J . Parasit. 9: 183 - 198. 105. Vercammen-Granjean, P.H. 1951: Sur l a Chaetotaxie de l a l a r -vae infestante de Schistosoma man-. son!. Annales de Parasitologie- Hum-aine et Comparee. 26: 412 - 414.' Wall, L.D. 1941: L i f e history of Spirorchis elephantis Cort, 1917 a new blood-fluke from Chrysemys  p i c t a . Amer. Mid. Nat. 25(2): 402 -412. Wu, Liang-Yu. 1953: A study of the l i f e history of T r i c h o b i l -harzia cameroni sp. nov. (Para. Schis-tosomatidae) . Can. Jour. Zool. 31: 351 - 373. Yolles, T.K., Moore, D.V., De G u i s t i , D.L., Ripsom, C.A. and Meleney, H.E. 1947: A technique for the perfusion of laboratory animals for the recovery of Schistosomes. J. Parasit. 33(5): 419 - 426. 

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