PARASITES 



357 



•^, lifi! 





mm 



experimentateurs connaissent parfaitement les alterations de degene rescence 

 et d 'infiltration qu'on rencontre constamment dans les reins atteints de 

 coccidiose, afin de ne pas mettre en relation ces phenomenes avec d'autres 

 causes etrangeres au coccidium qui n'est pas toujours bien reconnaissable, 

 qui n'est pas toujours reconnu et qui, pour le passe, a constitue souvent une 

 cause d'erreur." This statement could well be broadened to include the 

 other organs infected by the parasite. 



Sarcosporidia 



Sarcocystis muris blanchard. — This was the first species of Sarcocystis 

 to be described, having been discovered by Meischer in 1843, infecting the 

 muscle of mice. Since that time it has 

 been found in the rat, and other species 

 have been found infecting various other 

 animals. However, the most extensive 

 studies have been with S. muris since its 

 hosts can be easily infected by feeding 

 them infected tissue. 



These parasites (Fig. 139) can be seen 

 as tiny white streaks known as 

 iVIeischer's tubes" imbedded in striated 

 muscle tissue or less commonly in non- 

 striated muscle. The tubes may be as 

 much as 5 cm. long or they may be 

 so small as to be seen only with the 

 microscope. They are filled with sickle- 

 shaped spores called "Rainey's cor- 

 puscles." When the spores are ingested by the host a small amoeboid body 

 is liberated which penetrates the epithelial cells of the intestine. Here 

 schizogony occurs producing merozoites which make their way to the 

 muscle tissue where after about forty days multinucleated plasmodia can 

 be found. Cells may be liberated and reinfect other muscle fibers until an 

 intense infection is reached. Ultimately development progresses to form 

 the Meischer 's tubes containing the spores. 



In some cases no serious results are apparent with the infection, although 

 death of mice occurs with heavy infection. It has been shown that Sarco- 

 sporidia produce a toxic substance, and this is probably responsible for the 

 death of the host. For a more detailed discussion see Wenyon (43). 



■ ». B»htn "' 



Fig. 139. — Sarcocystis muris em- 

 bedded in the striated muscle of the 

 mouse. Cross section of a " INIeis- 

 cher's tube." (X75.) 



