POISONS FROM PARASITES 



281 



laryngeal muscles being infected, but how the infec- 

 tion was contracted is not known with certainty, 

 unless the parasites were acquired in the food. 



While the Sarcosporidia of domestic animals seem 

 to be relatively harmless, the parasite that infests 

 mice is remarkably fatal to the hosts. The organism 

 produces a definite 

 poison or toxin known 

 as sarcocystin, which 

 is rapidly fatal to the 

 infected animal. Sar- 

 cocystin has been 

 isolated from the 

 spores, and shown to 

 have fatal effects on 

 animals. 



In most cases the 

 Sarcosporidia are 

 found in the striped 

 muscles of the body 

 of the host, but they 

 also occur in un- 

 striped muscle, and 

 even the heart muscle 

 may become infected, as in the African mouse bird, 

 Colius erythromelon. The ability of the parasite to do 

 harm depends on its power of spreading in the host. 

 The more overrun the body of the host is, the more 

 danger there is to its health. 



Usually the occurrence of the Sarcosporidia is 

 shown by whitish streaks or patches in the 

 muscles. These streaks are known as Miescher's 



FIG. 56 PIECE OF BIRD'S MUSCLE 

 SHOWING SPORES OF SARCOCYSTIS 



Walls of chambers represented slightly 

 diagrammatically 



