of the acetabulum. The testes are branched and situated in the posterior portion of the body, one behind the other. The ovary is trilobate and anterior to the testes. The uterus is moderately developed, and its coils are anterior to the genital glands. The vitellaria are moderately developed and occupy about the middle third of the body. The eggs are 28 to 30 μ in length by 15 to 17 μ in breadth, operculated, almost black in colour, and contain a ciliated embryo. Probably its immature stages are passed in a mollusc (?Melania obliquegranulosa, M. libertina) or other small, soft-skinned, fresh-water animal. According to Yokagawa, cercariæ of this species are found in Japan in fresh-water fish of the family Cyprinidæ. Quite recently Kobayashi has traced the cercariæ into a variety of fresh-water fish in which they become encysted in the muscular tissue and advance in development. In cats, dogs, rabbits, guineapigs, and rats, fed on infected fish, mature C. sinensis, producing eggs, were found after twenty-six days from the time of feeding.
Fig. 164.—Clonorchis sinensis.
(Partly after Looss.) a, Magnified; b, natural size.
(See text.)
Pathogenesis.—C. sinensis inhabits the bile-ducts and gall-bladder. It thickens the biliary canals and expands them in places into cavities and diverticula as large as filberts. In these cavities vast numbers of parasites may be found. The diverticula communicate with the bile-ducts, along which the ova of the parasites, and sometimes the parasites themselves, escape into the intestine. The affected liver is enlarged as a whole, although the tissue in the immediate neighbourhood of the diseased bile-ducts is atrophied. The spleen, also, may be hypertrophied, and the intestine in a condition of chronic catarrh. Some instances are recorded of the presence of this trematode in the pancreatic ducts, in the duodenum, and in the stomach.
This parasite, which for long was supposed to be
