352 PARASITES OF THE DOMESTIC ANIMALS 



tory of the Sarcosporidia or as to the mode by which they infect. They 

 are known to be fatal to mice, and it has been found that when mice are 

 fed upon the flesh of other mice containing Sarcosporidia they become 

 infected. Hence the conclusion follows that natural transmission occurs 

 in these animals through their habit of nibbling at their dead; but this 

 method of transfer can hardly be considered in the case of sheep, cattle, 

 and horses, and the mode of infection in these animals remains a prob- 

 lem. 



In an article upon the Sarcosporidia encountered in Panama (Journal 

 of Parasitology, March, 1915), Darling suggests that these muscle 

 parasites of vertebrates are aberrant forms of the Neosporidia of in- 

 vertebrates, and points to the faciUty with which herbivora may in- 

 gest Neosporidia with leaves and other vegetation bearing infected 

 invertebrates and their droppings. "Is it not possible," Darling writes, 

 "that Sarcosporidia may be sidetracked varieties of some of the Neo- 

 sporidia of invertebrates which have invaded the musculature of a 

 hospitable though by no means definitive host and are unable to con- 

 tinue further their life cycle and escape from a compromising and aber- 

 rant position?" The high incidence of infection among sheep, cattle, 

 horses, and swine is evidence favoring this explanation. 



