PROTOZOA 425 



the same way that the paramecium * can be stimulated by 

 artificial means. It is a recognized fact that many of the 

 blood -diseases are characterized by relapses in which the or- 

 ganisms reappear after having disappeared from the circu- 

 lation. 



Pathogenesis. The extent of the effect of sarcosporidia 

 upon living animals is not fully known. 



In some cases the cyst wall calcines and the contents of 

 the cyst degenerate, with apparently no harm to the host, in 

 other cases the cysts burst and their contents spread into the 

 surrounding tissue, producing abscesses and tumors as with 

 many myxosporidia and sometimes causing the death of the 

 host. 



The symptoms of sarcosporidiosis in the pig are described 

 as paralysis of the hind extremities, a skin eruption, and gen- 

 eral systemic symptoms, such as increased temperature and 

 pulse. 



In sheep especially, the disease often causes fatal epi- 

 zootics. In the mouse, Sarcocystis muris is a deadly parasite. 



Laveran and Mesnil claim to have extracted a toxin (Sar- 

 cocystin) by means of glycerine or a salt solution, which they 

 have found extremely toxic for experimental animals (0.0001 

 gm. kills 1 kgm. of rabbit). The dried and powdered extracts 

 are also virulent. These extracts will remain virulent for a 

 long time in the ice box but will not withstand heating above 

 60 C. for any time. 



Minchin and Fantham 2 have described a new species, 

 Rhinosporidium kinealyi, to be the apparent cause of a tumor- 

 like growth of connective tissue in the nasal cavities of the 

 natives of India. Watson 3 finds that sarcosporidia may be- 

 come a grave menace to the life of their hosts. He calls at- 



* By changing the food the cultures of paramecium that had 

 almost lost vitality were restored by feeding beef broth for several 

 days, and another cycle of cell generations produced. 



2 Minchin and Fantham. Quarterly Jour, of Mic. Science, Vol. 

 XLIX (1905) p. 521. 



3 Watson. Jour, of Path, and Therap., Vol. XXII (1909) p. 1. 



