458 



PROTOZOOLOGY 



gestive tract of a specific host through mouth, it germinates and 

 the sporozoites are set free (Fig. 212). These sporozoites develop 

 into trophozoites either in the gut-lumen or within the host cells, 

 and undergo schizogony (c), which may be binary or multiple fis- 

 sion or budding. The fully grown trophozoites become paired as 

 in Eugregarinina and encyst, in which condition they undergo 

 sexual reproduction. Each individual which is now a gametocyte 



Fig. 212. The life-cycle of Schizocystis gregarinoides, XlOOO (L^ger). 

 a, germinating spore; b, growth of schizonts; c, schizogony; d, two 

 gametocytes and their association; e, stages in gamete formation, f, 

 zygote formation, g, cyst containing zygotes, each of which develops into 

 a spore shown in a. 



produces gametes (d-e). Fusion of two gametes follows (/). The 

 zygote develops into a spore containing 1-8 sporozoites (g, a). 



One spore from 2 gametocytes Family 1 Ophryocystidae (p. 459) 



Two or more spores from 2 gametocytes 



Family 2 Schizocystidae (p. 460) 



