THE PROTOZOAN SUBGROUPS 



351 



auto-infective process the entire skeletal musculature may become 

 affected. More or less destruction of muscle tissue is thus brought 

 about which necessarily is relatively injurious to the host; furthermore, 

 the effect is contributed to by the extremely toxic nature of the parasites 

 themselves. 



Importance of Sarcosporidiosis and Mode of Infection. — Hosts show- 

 ing high incidence of infection with Sarcosporidia among domestic 

 animals are pigs, sheep, cattle, and horses, the infecting species in each 

 case being Sa7-cocys(is miescheriana occurring in pigs, S. tenella in sheep. 



Fk;. 172. — Various foini.s of Sarcospoiiilia. _'. S:iii(h\ >tis lilani-hanli. Longidtudinal 

 section of an infected muscle with yount; iiidi\i(lual (after Ciawley, from Doflein, from 

 VanEeckc, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 3. Sarcocystis tenella in a 

 Purkinje cell of the heart of a sheep (after Crawley, from Doflein, from Schneidemuhl, 

 Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 4. Sarcocystis tenella in the wall of the 

 esophagus of a sheep (after Crawley, from Doflein, from Schneidemuhl, Cir. No. 194, Bu. 

 An. Ind., U. S. Dept. Agr.). 5. Sarcocystis muris in muscles of mouse (after Crawley, 

 Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 



S. hianchardi in cattle, and S. berirami in horses. In these animals the 

 infection has been considered as of little pathologic importance; the 

 sarcosporidiosis is apparently never fatal, and it is rare to find an animal 

 visibly affected. This conclusion, however, may be modified somewhat 

 by further study of the parasite, warranted b}' its prevalence, toxicity, 

 and possibly greater pathologic import than at present supposed. 

 Up to the present time little has been brought to light as to the life his- 



