12 



Scientific Proceedings (25). 



5 (261) 



A sporozoan found in the peptic glands of the common mouse. 



By E. E. TYZZER. 



\From the Laboratory of the Caroline Brezver Croft Fund Cancer 

 Commission of Harvard University '.] 



This organism occurs frequently in the gastric glands of tame 

 mice, but has not yet been found in wild mice, of which only a 

 small number have been examined. It is extracellular in all stages 

 of its development thus far observed. It presents structural char- 

 acteristics without which it would be impossible for it to develop 

 on the surface of the secreting gland-epithelium, and also produces 

 structural changes in the gastric mucosa so that it is to be consid- 

 ered a true parasite. It is evident, from the morphological study 

 of the various forms present, that this parasite has an asexual and 

 a sexual mode of reproduction. All forms during their growth 

 possess a definite limiting membrane at one point of which is a 

 knob-like projection which represents an organ of attachment, evi- 

 dently analogous to the epimerite of the Gregarinida. This pro- 

 jection gives to the organism a somewhat flask-shaped form. 

 Occasionally a delicate thread extends outward from this projection, 

 but I have been unable to determine whether or not this belongs 

 to the structure of the organism. One or more globules, which are 

 stained either by Sudan III or by osmic acid, are found in each 

 organism. In ordinary preparations these appear as vacuoles. 

 The developmental stages are briefly outlined in the following 

 description. 



Cryptosporidium muris, spec. nov. (unclassified). Development 

 extracellular. In form flask-shaped, either spheroidal or ellipsoidal. 

 All forms, during the period of growth, possess a relatively thin 

 limiting membrane, an organ of attachment (epimerite?), and each 

 contains one or more globules of fat which during segmentation are 

 to be found in the residual body. 



Schizont, after division of its chromatin, segments into eight 

 banana-shaped merozoites, each possessing a demonstrable nucleus 

 with a single karyosome. The substance of the organism is 

 nearly all utilized in the development of the merozoites. Resid- 

 ual mass small and contains fat globule. 



