GREGARINIDA 293 



According to Wenyon, in a typical Eugregarinina, Lankes- 

 teria culicis (Fig. 123) of Aedes aegypti, the development in a 

 new host begins when a larva of the mosquito ingests the spores. 

 From each spore are liberated eight sporozoites (j), which enter 

 the epithelial cells of the stomach and grow (a). These tropho- 

 zoites 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 trophozoites enter the Malpighian 

 tubules, where they become associated in pairs and encyst (c). 

 The two nuclei divide repeatedly and produce large numbers of 

 gametes {d-f) which copulate in pairs {g). The zygotes thus 

 formed develop into spores, each possessing eight 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 the 

 water. Larvae swallow the spores and acquire infection. 



Two legions are distinguished here: 



Trophozoite single-chambered Legion 1 Acephalina 



Trophozoite with more than one chamber Legion 2 Cephalina 



Legion 1 Acephalina Kolliker 



Genus Monocystis Stein. Body highly contractile and mo- 

 tile. A large residual mass of cytoplasm after sporulation. Spore 

 fusiform, symmetrical, with eight sporozoites. Common and 

 widely distributed parasites in the seminal vesicles of various 

 species of Lumbricus and Pachydrilus and also in microcrusta- 

 ceans. Numerous species. Several species frequently may occur 

 in a host individual at the same time and, consequently, 

 specific identification is a matter of great difficulty. 



Monocystis rostrata Muslow (Fig. 124, a-d). In the seminal 

 vesicle of Lumbricus terrestris. 



Genus Zygocystis Stein. Pyriform trophozoites are paired 

 in young as well as mature stages. The endoplasm is not vacuo- 

 lated. The spore contains eight sporozoites. In Lumbricus and 

 crustaceans. 



Zygocystis cometa Stein. In the seminal vesicle and body 

 cavity of Lumbricus agricola. 



Genus Pleurocystis Hesse. Trophozoites elongated spindle- 



