SPOROZOA 



95 



As a type we will take a simple form of the highest group, the 

 Gregarinidaceae, Monocystis, which inhabits the seminal vesicles of 

 the earthworm. In its youngest state, the " sporozoite," it is a 

 naked, sickle-shaped cell, which probably makes its way from the 

 gut into one of the large radial cells of the seminal funnel, where 



FiQ. 31.~Lankesteria ascidiae, sliowiiig lite -cycle. a', b, c, Sporozoites in digestive 

 epithelium cells of host ; d, e, growth stages ; /, free gregarine ; g, association ; 

 h, encystment ; i, J, brood - divisions in associated mates; Jc, pairing- cells ; 

 I, syngamy : m, zygote ; n, o, p, nuclear divisions in spores ; q, cyst with adult 

 spores, each' containing 8 sickle-germs. (After Luhe, modified from Siedleclci.) 



it attains its full size, and then passes out into the vesicles or 

 reservoirs of the semen, to lie among the sperm morulae and 

 young spermatozoa. The whole interior is formed of the opaque 

 endosarc, which contains a large central nucleus, and is full of 

 refractive granules of paramylum or paraglycogen,^ a carbohydrate 

 allied to glycogen or animal starch, so common in the liver and 

 ' For its reactions see Biitschli, Arch. Proiist. vii. 1906, p. 197. 



