530 



PROTOZOOLOGY 



develops into the sporozoites, thus developing into a spore. The 

 spores germinate when taken into the alimentary canal of a host 

 animal and the life-cycle is repeated. 



According to Wenyon, in a typical Eugregarinina, Lankesteria 

 culicis (Fig. 225) of Aedes aegypti, the development in a new host 

 begins when a larva of the latter ingests the spores which had been 

 set free by infected adult mosquitoes in the water. From each spore 

 are liberated 8 sporozoites (j), which enter the epithelial cells of the 

 stomach and grow (a). These vegetative forms leave the host cells 

 later and become mingled with the food material present in the 

 stomach lumen of the host (6). When the larva pupates, the sporad- 

 ins enter the Malpighian tubules, where they encyst (c). The re- 

 peated nuclear division is followed by formation of large numbers 

 of gametes (d-f) which unite in pairs (g). The zygotes thus formed 

 develop into spores, each possessing 8 sporozoites (h). Meanwhile 

 the host pupa emerges as an adult mosquito, and the spores which 

 become set free in the lumen of the tubules pass into the intestine, 

 from which they are discharged into water. Larvae swallow the 

 spores and acquire infection. 



Eugregarinina are divided into 2 tribes : 



Trophozoite not septate Tribe 1 Acephalina (p. 531) 



Trophozoite septate Tribe 2 Cephalina (p. 541) 



Fig. 226. Encystment in Gregarina blattarum, X60 (Sprague). a, a 

 trophozoite with epimerite and 3 pairs of syzygy; b, association of three 

 individuals; c-h, encystment as seen in a single pair in about one hour. 



