362 SPOEOZOA. 



gives a list of thirty- nine species of Sarcocystis from a variety 

 of hosts, but agrees with Alexeieff that there is no means 

 of distinguishing the supposed species. 



Babudieri (1932) regards the Saecosporidia as more 

 closely related to the Coccidia than the Cnidospoe.idia. He 

 divides the subclass into Saecosporid-ia s. str. (including 

 the famihes Sarcocystidse and Fibrocystidse) and Globidia, 

 including the family Globididse. The Sarcocystidae includes 

 the genus Sarcocystis with twenty-two species. The Fibro- 

 cystidse includes Fihrocystis and Besnoitia with two species 

 each. The Globididse includes Globidium with five species 

 and Ileocystis with one species. The work should be referred 

 to for the diagnostic features, synonymy, and hosts of various 

 species. Krause and Goranoff (1933) tabulate the morpho- 

 logical differences of forms described from birds. They 

 succeeded in infecting the fowl with the strain from the 

 buffalo. 



Pathogenicity. — In many cases, even with fairly heavy in- 

 fection, the host may not be adversely affected ; but in others 

 the host sooner or later dies as the result of muscular degenera- 

 tion. The organisms are known to produce a peculiar sub- 

 stance called sarcocystin, which is highly toxic when injected 

 into other animals. Teichmann and Braun (1911) showed that 

 rabbits could be immunized against the toxin, and that the 

 serum contained antibodies which could produce passive 

 immunity in other animals. 



I. Order SARCOSPORIDIA s. s^r., Babudieri, 



1932. 



Spore banana-shaped ; the cyst is wholly or partially of 

 parasitic origin, and the spore produces metachromatic granules 

 and secretes a toxin kno^oi as sarcocystin. The spore is 

 produced by the prohferation of the pansporoblast, and the 

 sporoblast has a peripheral situation in the cyst. 



Identification Table of Families. 



1 (2). Cysts elongated in form, parasitic in the [Babudieri, p. 363. 



striped muscle-fibres Sarcocystidae 



2 (1). Cysts rounded in form, parasitic in the [Babudieri. 



connective tissue or plain muscle-fibres . Fibrocystidse* 



