SPOROZOA, GREGARINIDA 



529 



Leidyana erratica (Watson, 1916), Gregarina blaitarum (Sprague, 

 1941) (Fig-. 226), etc. Within the cyst-membrane, the nucleus in each 

 individual undergoes repeated division, forming a large number of 

 small nuclei which by a process of budding transform themselves into 

 numerous gametes. The gametes may be isogamous or anisogamous. 

 Each of the gametes in one gametocyte appears to unite with one 

 formed in the other, so that a large number of zygotes are produced. 

 In some species such as Nina gracilis the microgametes enter the 

 individual in which macrogametes develop, and the development of 

 zygotes takes place, thus producing the so-called pseudocyst. The 

 zygote becomes surrounded by a resistant membrane and its content 



Fig. 225. Diagram illustrating the developmental cycle of Lankesteria 

 culicis (Wenyon). a, entrance of sporozoite into the mid-gut epithelium 

 and growth of trophozoites; b, mature trophozoite found in the lumen 

 of gut; c, association of two gametocytes prior to encystment; d-f, gamete 

 formation; g, zygote formation; h, development of spores from zygotes; 

 i, a spore; j, emergence of eight sporozoites from a spore in a new host 

 gut. 



