A CNIDOSPORIDIA 



327 



parasitic mass is an elongated multinucleate body which may or 

 may not divide into as many uninucleate bodies as there are 

 nuclei. These become the centers of infection in other muscle 

 fibers. Some trophozoites grow in size and the body becomes 

 divided into parts, in each of which spores are formed (Fig. 141). 

 According to some authors, the spores themselves are capable of 

 fission. The host muscle fiber harboring the trophozoite, may 

 vary in size from microscopic to as large as 5 centimeters (Fig. 



^ Connective tissue layer 



Fibrous zone 





External 



Median 

 Internal 



Cyst membrane 



Sporoblasts 



Spores 



Fig. 141 Schematic drawing showing part of a cyst of Sarcocystis tenella in 

 sheep. X about 1000 (After Alexeieff). 



140). They are cylindrical with more or less pointed extremities 

 and with a somewhat lobulated surface, and opaque whitish. 

 They were formerly called "Miescher's tubes" (Fig. 140). 



As to the pathogenic effect of the parasites upon the host 

 animal, fatal cases are not uncommon. In heavily infected 

 animals extensive muscular degeneration appears and the hosts 

 die, soon or later, from the infection. One peculiarity of the 

 Sarcosporidia is that these organisms contain certain toxin, to 

 which Laveran and Mesnil gave the name sarcotoxin, and which 



