THE PROTOZOAN SUBCJROUPS 



351 



auto-infective process the entire skeletal muscnlature may become 

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

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

 the effect is contiibuted to l)y the extremely toxic nature of the parasites 

 themselves. 



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

 hig his;h incidence of infection with Sarcosporidia among domestic 

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

 case being Sarcocystis miescheriana occurring in pigs, .S'. lenvlhi in sheep, 



Fig. 172. — Variou.s forms of Sarcosporidia. — 2. Sarror-\ stis l)lanrhaifli Loiimdtuihiial 

 section of an infected muscle with 3'OunK indi\'idual (aftci Ciawlcj, lioni Doflcin, from 

 VanEecke, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 3. Sarcocy.stis 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. Sarcoej'.stis muris in muscles of mou.se (after Crawlcv. 

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



»S'. hlancliarcli in cattle, and S. bertrami 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 

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

 by further study of the parasite, warranted by its prevalence, toxicity, 

 and possibh' greater pathologic import than at present supposed. 

 Up to the present thne little has been brought to light as to the life his. 



