Thesis (Ph. D.)--University of Illinois, 1917. / "Contributions from the Zoological laboratory of the University of Illinois ... no. 98." Thesis note on verso of t.p. Bibliography: p. 96-101.

Thesis (doctoral)--Académie de Paris, 1885. / "Serie A. no. 72 ; No. d'ordre 538." Includes bibliographical references.

Thesis - Wisconsin. / Vita. Bibliography: leaves 315-324.

Six species of larval trematoda were discovered in the mollusca of Burnaby Lake, B.C. These included two species each of echinostome cercariae, furcocercous cercariae and xiphidiocercariae. Life cycle studies were carried out with each of these larval species. A series of infection experiments proved one of the echinostome cercariae to be the larva of Echinoparyphium recurvatum which was shown to utilize several species of snails at Burnaby Lake as first and second intermediate hosts. Morphological and experimental evidence indicated the other echinostome cercaria to be the larval stage of Echinostome revolutum, an adult trematode parasitic in muskrat of Burnaby Lake. Both natural and experimental first and second intermediate hosts of E. revolutum at Burnaby Lake were established. The two xiphidiocercariae were found to be very similar morphologically, but were classed as separate species on the character of the stylet organ. One xiphidiocercaria bears much resemblance to Cercaria. albui, Brooke 1943, the other appears to be an undescribed species. The first intermediate snail hosts for these xiphidiocercariae have been found at Burnaby Lake and a Gammarus species has been demonstrated as being an experimental second intermediate host. Both the furococercous cercariae discovered appear to be new species. One of these forms bears some resemblance to Cercaria oregonensis. Macfarlane and Macy 1946, and has been found capable of producing a schistosome dermatitis in humans. A high incidence of larval trematode infection exists in the snails of Burnaby Lake. Area differences have been noted in snail populations and their trematode fauna. Additions have been made to larval trematode distribution and host records. / Science, Faculty of / Zoology, Department of / Graduate

This thesis investigates the effect of light, and to a lesser extent of gravity, on the distribution of the two free-living larval stages (miracidia and cercariae) of the digenetic trematode Bunodera mediovitellata. Test tubes, with various portions blackened, were illuminated by a horizontal white light, to determine the photoresponse and georesponse of miracidia and cercariae. Four-arm test chambers were used to determine the lowest light intensity at which miracidia and cercariae reacted. This intensity proved to be the same for both miracidia and cercariae even though miracidia are photonegative and cercariae are photopositive. Two-arm test chambers, illuminated with monochromatic light, were used to determine which wavelength(s) the larval stages were responding to. Cercariae showed a single response peak at 550Anm. while miracidia showed two peak's; one at 550 run. and the other at 650 nm. The second peak may be due to a screening effect by the pigment which surrounds the photoreceptor. The experimental results support the hypothesis that behavioural responses of free-living miracidia and cercariae to environmental stimuli guide? them to the general area of their next host and thereby increase! the chance of host-parasite contact. The photonegative and geopositive behaviour of miracidia of B.mediovitellata would keep them on or near the bottom of the pond and in the general habitat of the next host, Pisidium casertanum. Cercariae are photopositive and either geopositive or are very weak swimmers. Their behaviour would keep them on the bottom of the pond in the prefered habitat of the next probable host, an insect nymph or a crustacean. A model depicting the possible theoretical combinations of photoresponse with georesponse was constructed. A survey of the literature was undertaken to find larval stages with known photo-response and georesponse. The responses of these larvae were tabulated and compared to the model. In each case, the responses of the larvae supported the hypothesis that a complementary response to light and gravity should occur more frequently in nature than antagonistic reponses or a response to either light or gravity alone. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

In channel catfish (Ictalurus punctatus), the digenetic trematode B. damnificus, causes morality and reduced growth. Previous research has documented the hosts for B. damnificus are: the American white pelican (Pelecanus erythrorhynchos), the snail (Planorbella trivolvis) and the channel catfish. The goals of this research were to confirm the life cycle of B. damnificus in a single life cycle study fulfilling Koch’s postulates; determine if the snail, Biomphalaria havanensis-obstructa, could serve a host for B. damnificus, and examine the pathology of B. damnificus in channel catfish. American white pelicans (AWP) were artificially infected with B. damnificus metacercariae which matured to the adult stage (4 days) and shed ova. The ova hatched (12- 53 days), releasing miracidia which infected P. trivolvis and developed into B. damnificus cercariae which were shed (23 days), used to infect catfish and matured into metacercariae in the superficial muscle (23 days). Infected catfish were fed to AWP, and the metacercariae matured to patent adults (7 days) and shed ova, thus completing the life cycle. A second study was performed to determine if the snail, Biomphalaria havanensis- obstructa found in commercial catfish ponds could serve as an intermediate host for B. damnificus. Parasite free Biomphalaria havanensis- obstructa exposed to B. damnificus ova shed cercariae that were molecularly identified as B. damnificus; confirming Biomphalaria havanensis- obstructa is a potential intermediate host for B. damnificus. A third study examined the pathology associated with B. damnificus infections in channel catfish. Cercariae, confirmed by PCR to be B. damnificus, were used to infect fingerling catfish at 200, 100, 50, 25 and 0 cercariae/ fish. The fish were euthanized 3, 4, 5 and 6 days post-infection, gross observations were noted and tissues were collected for histology. Mortalities of 20- 100% occurred in fish challenged with 200 cercariae by day 6 post-infection. At day 6 post-infection, fish challenged with 100- 200 cercariae had loss of hepatocytes vacoulation and lymphoid depletion in the spleen. Metacercariae were not only present in the subcutaneous muscle but were also in the epidermis, behind the skull, within the muscular layers urinary bladder and around the heart.

No description available.

The fish Cymatogaster aggregata, Embiotoca lateralis and Phanerodon furcatus served as definitive hosts for the trematode Telolecithus pugetensis Lloyd and Guberlet. Eggs that were collected from the terminal part of the uterus of mature worms were found to have undergone several cleavages, but complete development was observed only in some eggs that were eaten by the clam Transennella tantilla which served as the first intermediate host. The miracidium that emerged from the egg was oval and covered with long cilia. Except for germ balls, no other internal structures were seen in the miracidium. In the clam sporocysts were found around the intestine in the vicinity of the gonad. No mother sporocyst generation was identified. Immature sporocysts were most frequent in the fall and winter, while mature sporocysts were most common in the spring and summer. The sporocysts were cylindrical, slightly motile, and contractile. Mature sporocyst infections were often of two size groups--one short and the other long. It appeared plausible to the author that the sporocysts may reproduce by transverse fission. Clams that harbored sporocysts were always sterile. Brevifurcate cercariae which developed in the sporocysts left the clam via the excurrent siphon. The cercaria could not swim, instead it moved in a leech-like manner. If a cercaria touched the soft parts of a potential host, it would attach, penetrate within one and one-half to two hours, and become an encysted metacercaria within 24 hours. The following pelecypods that were found in the same environment as the first intermediate host served experimentally as second intermediate hosts: Clinocardium nuttalli, Schizothaerus nuttalli, Transennella tantilla, Macoma nasuta, and Tellina salmonea. In the laboratory the gastropods Acmaea digitalis and Littorina planaxis, which were not found in the same environment as the other hosts, served as second intermediate hosts, indicating that among molluscs host specificity was primarily ecological. In the field and in the laboratory, the clams Tellina salmonea and Macoma nasuta were the most highly infected with metacercariae indicating that there was a certain degree of physiological specificity. / Graduation date: 1964

Thesis--Hebrew University. / Added title page and abstract in Hebrew. "Reprint from the Bulletin of the Research Council of Israel, Section B: Zoology, vol. 9B, July 1960, no. 2-3."