528 PROTOZOOLOGY 



Suborder 1 Eugregarinina Dofiein 



This suborder includes the majority of the so-called gregarines 

 which are common parasites of arthropods. When the spore gains en- 

 trance into a suitable host, it germinates and the sporozoites emerge 

 and enter the epithelial cells of the digestive tract. There they grow 

 at the expense of the host cells which they leave soon and to which 

 they become attached by various organellae of attachment (Fig. 

 235). These trophozoites become detached later from the host cells 

 and move about in the lumen of the gut. This stage, sporadin, is ordi- 

 narily most frequently recognized. It is usually large and vermiform. 

 The body is covered by a definite pellicle and its cytoplasm is clearly 

 differentiated into the ectoplasm and endoplasm. The former con- 

 tains myonemes (p. 62) which enable the organisms to undergo glid- 

 ing movements (Watson, 1916). 



In one group, Acephalina, the body is of a single compartment, 

 but in the other group, Cephalina, the body is divided into two com- 

 partments by an ectoplasmic septum. The smaller anterior part 

 is the protomerite and the larger posterior part, the deutomerite, 

 contains a single nucleus. In Pileocephalus (Fig. 236, s) the nucleus is 

 said to be located in the protomerite and according to Goodrich 

 (1938) both the protomerite and deutomerite of Nina gracilis contain 

 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. 112). 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. Cytology (Gohre, 1943). 



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. What differences exist between the two individ- 

 uals that become associated is not well known. But Muhl (1921) re- 

 ported in Gregarina cuneata, the granules in the primite and the 

 satellite stained differently with neutral red. Sporadins usually en- 

 cyst in pairs and become gametocytes. This process following bi- 

 association was observed in a number of species; for example, in 



