430- PROTOZOOLOGY 



a nucleus. The endoplasm contains numerous spherical or ovoidal 

 bodies which are called zooamylon or paraglycogen grains and 

 which are apparently reserve food material (p. 99). The proto- 

 merite may possess an attaching process with hooks or other 

 structures at its anterior border; this is called the epimerite. The epi- 

 merite is usually not found on detached sporadins. Goodrich ob- 

 served recently that in Nina the protomerite is a knob-like part of 

 the gregarine when contracted, but expands freely and used as a 

 mobile sucker for attachment to the gut epithelium of the host Scolo- 

 pendra. Presently multiple filiform epimerite grows at the free edge 

 of the sucker and penetrates between the host cells. Epimerite bear- 

 ing trophozoites are called cephalins. 



Many gregarines are solitary, others are often found in an endwise 

 association of two or more sporadins. This association is called 

 syzygy. The anterior individual is known as the primite and the pos- 

 terior, the satellite. Sporadins usually encyst in pairs and become 

 gametocytes. Within the cyst-membrane, the nucleus in each indi- 

 vidual 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 

 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. 201) 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 (A). Meanwhile 

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



