XIX] PROTOZOA CAUSING DISEASE 507 



large oval forms, and in their turn, on their ripening, grow 

 into these latter. 



It can be shown that the coccidia first appear in the 

 epithelium of the intestine, and from here they find their 

 way into the epithelium of the hepatic duct and gradually 

 into the bile ducts within the liver. Here their multiplica- 

 tion produces saccular, tubular, and cystic enlargements of 

 the interlobular bile ducts, the wall of which becomes 

 thickened by connective tissue, and folded in many ways. 

 In this manner numerous whitish irregularly shaped firm 

 nodules and cysts are formed in the liver, which, when cut 

 into, show a cavity with the thick white wall folded 

 inwards. 



The columnar epithelial cells lining the hypertrophied 

 bile ducts, which harbour the coccidia, are, in fact, the soil 

 at the expense of which the coccidia grow and ripen ; these 

 latter in their turn, and for their own purpose, cause a 

 continuous multiplication of the epithelial cells. 



Leuckart in his work. Die Parasiten des Menschen, 2te 

 Aufl. i., gives an exhaustive account of the life-history of 

 the coccidium oviforme, the mode of passing into new 

 animals, and the changes and distribution of it. In the 

 human subject nodules of the liver have been observed 

 which were caused by coccidia, probably coccidium ovi- 

 forme. Gubler, Leuckart, Dressier, and Perls {see Leuckart, 

 loc. cit. p. 281) have observed such cases. Besides the 

 rabbit coccidium oviforme has been found in the intestines 

 of the dog, cat, sheep, guinea-pig, and pheasant. ^ 



■ Miescher's coccidia tubes occur in the muscles of the mouse occasion- 

 ally ; they are noticed as fine white lines which under the microscope are 

 tapering cylindrical granular masses, the latter in reality densely packed 

 crescentic or kidney-shaped pale corpuscles, about O'OI mm. long and 

 considered to be spores. (Leuckart, loc. cit.) 



