278 J. JACKSON CLAEKE. 



placed on damp blotting-paper in a Petri's dish,^ and kept at 

 room temperature (May — June). 



The ripe free parasites were uniformly much smaller (aver- 

 aging 18 X 13 fx) than the Coccidium oviforme of the 

 rabbit (averaging 32 x 22 fi). They were also of a more 

 rounded shape. When first examined the capsules of the free 

 parasites were completely filled by granular protoplasm, having 

 the usual dense, round, central body ; they were examined on 

 successive days for a fortnight, and I may briefly indicate the 

 results by saying that with the modification in size previously 

 alluded to they underwent the same changes as does C. ovi- 

 forme of the rabbit when placed under similar circumstances. 

 Thus on the sixth day most of the parasites had subdivided 

 (fig. 2) into four granular spheres, of which some possessed a 

 clear oval corpuscle placed as far as possible from the point of 

 meeting of the segments (fig. 3). On the eighth day the sub- 

 divisions (sporogonia) had assumed an oval form, and some pre- 

 sented a capsule and a difi'erentiation into spores and granular 

 residual matter (nucleus de reliquat). Many of the spores 

 showed the dumb-bell form described by Leuckart in C. ovi- 

 forme of the rabbit (see fig. 5), and in one or two cases I was 

 able to see the division of the C-shaped body into two comma- 

 shaped spores, as described by Balbiani. This arrangement of 

 lasting spores is, as in the case of the rabbit's Coccidium, often 

 departed from, and appearances such as are depicted in fig. 6 

 occur frequently. 



In order to have material for histological study, and to test 

 the time required for the manifestation of the disease, a young 

 healthy mouse, whose fseces were found to be free from Coc- 

 cidia, was fed with bread-sop containing some of the material 

 taken from the Petri dish after twenty-two days' exposure 

 to air.^ 



' This consists of two shallow glass dishes, one of which is larger than the 

 other, and when inverted forms a cover whicii excludes dust from the smaller 

 one. 



2 I have given the days on which the various appearances were first noted, 

 and I do not wish to convey an impression that on any given day all the 



