380 PROTOZOOLOGY 



and its cytoplasm is clearly differentiated into the ectoplasm and 

 endoplasm. The former cotains myonemes (p. 52) which enable 

 the organisms to undergo gliding movements. In one group, 

 Acephalina, the body is of a single compartment, but in the other 

 group, Cephalina, the body is divided into two compartments by 

 an ectoplasmic septum. The smaller anterior part is the proto- 

 merite and the larger posterior part, the deutomerite, contains a 

 single nucleus except in Pileocephalus (p. 404) in which the 

 nucleus is said to be located in the protomerite. The endoplasm 

 contains numerous spherical or ovoidal bodies which are called 

 zooamylum or paraglycogen grains and which are apparently 

 reserve food material (p. 94). The protomerite may possess an 

 attaching process with hooks or other structures at its anterior 

 border, which is called the epimerite. The epimerite is usually 

 not found on detached sporadins. Trophozoite with the epimerite 

 will be called the cephalin. Many gregarines are solitary, while 

 others are found often in an endwise association of two or more 

 sporadins. This association is called syzygy. The anterior in- 

 dividual is known as the primite and the posterior, the satellite. 

 Sporadins usually encyst in pairs and become gametocytes. 

 Within the cyst-membrane, the nucleus in each individual under- 

 goes 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 anisog- 

 amous. 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. The zygote becomes surrounded by a resistant 

 membrane and its contents develop 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 re- 

 peated. 



According to Wenyon, in a typical Eugregarinina, Lankestcria 

 culicis (Fig. 174) of Aedes aegypti, the development in a new host 

 begins when 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 epithehal 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 (b). When the larva pupates, the 

 sporadins enter the Malpighian tubules, where they encyst (c). 



