96 THE INVERTEBRATA 



swallowed by another of the same species, within which their cysts 

 are digested and a new infection begins by the sporozoites invading 

 cells of the host. These they eventually outgrow, and lie in a cavity 

 of the host, either entirely free or attached by an epimerite. 



Fig. 78. A diagram of the life cycle of Monocystis. A, Trophozoite adhering 

 to the seminal funnel of the host. B, Encysted syzygy. C, Formation of 

 gametes. D, Conjugation. E, Encystment of zygotes. F, Multiplication of 

 nuclei of the same. G, Formation of sporozoites (only four of the eight are 

 shown). H, Release of sporozoites in intestines of new host. I, Infestation of 

 sperm morula, ext. external coat of gamocyst; gam. gametes; int. internal 

 coat of gamocyst; res. residual protoplasm; spc. cells of sperm morula; spe. 

 tails of withered spermatozoa adhering to parasite; spz. sporozoites; zy 

 zygote. 



In comparing this life cycle with that of Etmeria, given above, it 

 should be noted that in the gregarines, whose female gametes are 

 merogametes and numerous, the "spores" (small sporocysts each 



