PARASITES 355 



cellular, C muris being strictl}' extracellular, while C. parvum might be 

 classed as intermediate. 



C. muris lives in the gastric glands. During growth the forms occur on 

 the surface of the glandular epithelium, and all forms except the merozoites 

 and sporozoites possess a limiting membrane and an organ bv which they are 

 attached to the surface of the epithelium. The schizonts, which reach a 

 maximum size of 7 )U by 6 ^t, give rise to eight merozoites. The mature 

 oocyst is approximately 7 /z by 5 yu, and it becomes a single spore containing 

 four sporozoites. ]Many of the sporozoites are set free before passing from 

 the stomach, and Tyzzer suggests that probably autoinfection may be 

 affected through sexual as well as through asexual reproduction. 



C. parvum develops in the cuticula of the epithelium of the intestinal 

 villi. The forms at first bury themselves in this layer, becoming attached by 

 an attachment organ to the membrane limiting the cuticula from the cyto- 

 plasm. As they grow they protrude from the free surface of the cuticula, 

 but they never penetrate the cytoplasm. Like C. muris, eight merozoites 

 are produced by each schizont and four sporozoites by each oocyst. The 

 maximum diameter of the schizonts is 5 [x, and the mature oocvsts do not 

 exceed 4.5 /x. 



Evidently both species are quite commonly and widely distributed 

 among laboratory mice. However, neither is of great importance path- 

 ologically, although Tyzzer reports that in extensive infections C. muris does 

 cause dilation of the gastric glands and some leucocytic infiltration of the 

 gastric mucosa. Xo inflammatory processes are reported resulting from 

 infection with C. parvum. 



Klossiella muris smith and johnson, 1902. — This sporozoan, which 

 Kudo (26) considers under the order Coccidia, infects the kidneys of mice. 

 It was first discovered by Smith and Johnson in 1889, and later they made a 

 study of it from the kidneys of adult gray mice caught in the animal room of 

 the laborator}- at Harvard University (36). They describe the external 

 appearance of the kidneys as being slightly enlarged with a ver}- delicate 

 mottling of the whole surface by minute, barely visible, grayish specks. 



European authors (22, 43) have since described it as a common parasite 

 of white mice. Cannarella (8) encountered it in his mice used for tumor 

 studies. In 7,7, mice of an experiment with artificially grafted tumors he 

 found the organism infecting the kidneys of 43.7% of the mice with a tumor 

 and j\.o^c of the mice lacking tumors. 



The schizogony cycle takes place in the endothehal cells of the capillaries 

 of the glomeruli. Young gametocytes produced by this asexual cycle make 



