1916.] NATURAL SCIENCES OF PHILADELPHIA. 35 



My studies do not extend beyond the formation of the zygote. 

 In mice killed one to two days after feeding, oval cells resembling 

 the zygotes, hut larger, are quite frequent. These are most abundant 

 in the villi beneath the epithelial row, but they also occur in the cells 

 and occasionally free in the lumen. Their ultimate fate has not 

 been followed, but Erdmann (1914) describes what seems to be 

 schizogony in the cells and subepithelial tissues of mice killed several 

 days after feeding, and it is not at all unlikely that the oval bodies 

 mentioned above are schizonts. 



One fact stands out clearly: the banana-shaped body of the Sar- 

 cosporidia is not a spore 1 . There was never any reason to suppose 

 that it was, even though this misleading designation has been used 

 exclusively in the literature during recent years. Labbe (1899) 

 designated it as a sporozoite, which, in view of its form, is far more 

 plausible, and may indeed be a correct designation, so far as it is 

 allowable to apply terms based on the conditions in the Telosporidia 

 to stages of Sarcosporidia. For if the oval bodies occurring in one- 

 and two-day mice give rise to the schizonts described by Erdmann, 

 and if the products of this schizogony give origin to the familiar 

 muscle cysts, then apparently the banana-shaped body is in some 

 respects at least the analogue of the coccidian sporozoite. 



As against this interpretation is the fact that in ( Joccidia, where 

 there is both schizogony and sporogony, the sporonts are derived 

 from merozoites. This would suggest that the banana-shaped 

 sarcosporidian element is a merozoite. Obviously, however, the 

 evidence at hand is not sufficient to warrant a conclusion. Accord- 

 ingly, it has been considered best to follow recent custom and to 

 retain the term spore, despite the fact that it is incorrect, for it is 

 believed that this procedure is less confusing than to adopt a 

 different designation which future discovery might show to be 



equally incorrect. 



Summary. 



(1) The spores of Sarcocystis muris, ingested by a mouse, may 

 reach the posterior part of the small intestine within one hour. 



(2) Invasion of the epithelium cells of the intestine may also take 

 place within the same time. 



(3) Upon reaching the lumen of the intestine, the spore rapidly 

 undergoes changes. The nucleus becomes larger and more con- 

 spicuous, and a distinct nuclear net becomes evident. The granules 

 characteristic of the spore as it occurs in the cyst either disappear 

 or become much less evident. Further changes, however, do not 

 take place unless the spore gains an intracellular situation. 



