A sporozoan found in the peptic glands of the common mouse

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 characteristics 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 considered 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, evidently analogous to the epimeute of the Gregarinida. This projection 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.