302 



THE SPOROZOA 



with symptoms like cholera, in a very short time; in a feebler 

 dose it produces a cachexy which usually ends fatally. In other 

 animals the action of sarcocystin is more feeble and transitory in 

 its effects. 



As regards the origin of Sarcosporidiosis, or the manner in 

 which it spreads, nothing can be said definitely at present, but 

 it is possible to put forward a few more or less probable surmises, 

 which will be found below (p. 308). 



(b) Morphology and Evolution. The youngest examples of the 

 trophozoite that have been observed 

 had already attained a length of 

 40 p. with a breadth of 6 p (Fig. 

 118, a). They are found as whitish 







Fio. 118. 



Stages in the growtli of Sarcocystis tenella of the 

 sheep, a, youngest observed stage in which the 

 radially striated outer coat has not appeared ; the 

 body of the trophozoite is already divided into a 

 number of cells or pansporoblasts (Jk). b and c, 

 older stages with numerous pansporoblasts and 

 two envelopes, an inner membrane and an outer 

 radially striated layer. (From Wasielewski, after 

 Bertram.) C 



opaque bodies limited by a fine, structureless cuticle. The 

 protoplasm of the trophozoite is already in part segmented up 

 to form a number of nucleated corpuscles or cells, which are 

 evidently homologous with the primitive spheres or pansporo- 

 blasts of the Myxosporidia, and may therefore receive the same 

 name. 



In the next stage the parasite, still intramuscular in position, 

 has increased in size and is surrounded by two coats (Fig. 118, b). 

 The outer coat, which is thick and shows a fine radial striation, 



