SARCOSPORIDIA 191 



Laveran and Mesnil) contain an obliquely striated body (tig. 109) often 

 homologized with the polar capsule, while the greater part of the spore 

 is taken up by the nucleate sporozoite. Several authors state that they 

 have also observed filamentous appendages (polar filaments) at one 

 end of the spores, and have seen two kinds of spores in the same 

 Sarcosporidium. Spores of various species of Sarcosporidia may 

 contain metachromatic granules, often centrally placed (fig. 109). 

 These granules may be metabolic or possibly may contain toxin 

 (see below). 



The gymnospores of Sarcocystis inuris, from the mouse, show active 

 boring movements when kept in saline solution warmed to 35 or 

 37 C. S. -tmiris is very deadly to its host. From their structure the 

 spores do not appear to have great powers of resistance to external 

 conditions. They measure 12 yu, by 3 p to 4 p or less. 



Laveran and Mesnil (1899) isolated a toxin from S. tenella of 

 the bheep and called it sarcocystin. This substance is especially 

 pathogenic to experimental rabbits. 



The duration of life of the Sarcosporidia is a comparatively long 

 one. The affected muscular fibres may remain intact and capable of 

 performing their functions for a long time, 

 but at last they perish, if the host lives long 

 enough. Thus the Sarcosporidia of the 

 muscles are then enveloped only by sarco- 

 lemma, and finally, when this likewise dis- 

 appears, they fall into the intra-muscular 

 connective tissue. In many cases the Sarco- 

 sporidia die off within their hosts, this, FIG. 109. Spores of Sarco- 

 according to Bertram, being brought about * j $*. 

 by a disintegration of the spores in the cen- b, stained, showing meta- 

 tral chambers. In other cases the leucocytes ^ r u , nialic x R an ( d Af n te u ; 

 play a part in the destruction of the Sarco- Laveran and Mebnii.) 

 sporidia, and sometimes it happens that lime 

 salts are deposited in and around the vacant cylinders. 



In some places pigs, sheep, mice and rats are infected with 

 sarcosporidiosis to a remarkable extent, in certain cases almost reach- 

 ing 100 per cent. Young animals also are infected, and perhaps 

 infection only takes place during youth. 



Although the natural mode of transmission of the Sarcosporidia 

 remains to be determined, yet various experimental researches on 

 the problem are of interest and importance. Theobald Smith (1901) 

 found that mice could be experimentally infected with S. muris 

 by feeding them with the flesh of other infected mice. The incuba- 

 tion period was a long one, namely forty to fifty days. Thus, on the 

 forty-hfth day after feeding young Sarcosporidia were found, and 

 seventy days after feeding spore formation began. Ripe spores were 

 found two and a half to three months after the commencement of 



