A Gastric Sporozoan. 



13 



Microgametocyte smaller than schizont (never exceeds 5 x 3.5 

 microns). Division of chromatin followed by formation of sixteen 

 or more microgametes which usually develop at the surface of the 

 organism farthest from the organ of attachment. The larger por- 

 tion of microgametocyte is left as a rounded residual body in which 

 there is usually a fat globule. 



Macrogamete or sporont, characterized by iodophilic granules 

 and by the development of a dense capsule. Process of matura- 

 tion and fertilization not determined. The entire organism is trans- 

 formed into a single ellipsoidal spore which measures 7X5 microns 

 and contains four sporozoites. Sporozoites about ten microns in 

 length, slender, fusiform, without demonstrable internal structure. 

 They lie parallel one with another within the capsule of the spore, 

 and are bent in U shape around the centrally situated residual 

 material. 



Habitat. — Gastric glands of Mus mus cuius. 



Since no description of this organism has been found, the 

 above name Cryptosporidium mitris is offered. No evidence has 

 been obtained indicating that this organism represents a portion 

 of the life cycle of any of the hitherto described parasites of the 

 mouse, and it seems probable that it passes through its entire 

 developmental cycle in the gastric glands. All the mice in certain 

 cages are infected with this parasite, and since the ripe spores are 

 found in the feces it is possible that infection follows the ingestion 

 of contaminated food. 



The systematic position of the organism appears uncertain. 

 In its possession of an organ of attachment and of iodophilic gran- 

 ules, it resembles the gregarines. In its morphology, in the lack 

 of motion in the adult, and in sexual dimorphism it resembles the 

 coccidia. If it is to be included in the latter group, it may pos- 

 sibly belong to the Family Asporocystidse (Doflein). 



