i66 



COMPARATIVE ANATOMY 



formed used to be known as sporoblasts, but now that their 

 nature is more fully understood they are more appropriately 



Fig. 35- 



A, part of a section through a gametocyte showing the gametes, gain, formed 

 at the periphery of a mass of residual protoplasm, rp ; rn, an abortive 

 nucleus in the residual protoplasm. , conjugation of the gametes in pairs 

 to form zygotes ; in zy the nuclear fusion is complete ; en, endocyst ; ep, 

 epicyst ; rp, residual protoplasm containing paraglycogen granules. C, the 

 zygotes have begun to secrete spore coats or sporocysts, and each is now a 

 definitive sporoblast, sp. D, a single sporoblast in which eight nuclei have 

 been formed by successive divisions of the conjugation nucleus. A", a trans- 

 verse section through the equator of a fully developed sporocyst showing 

 the nuclei of eight sporozoites surrounding a core of residual protoplasm, rp. 

 F, a fully developed sporocyst (pseudonavicella) containing eight sporo- 

 xoites, spz. (A-C after Cuenot ; 2VF original.) 



termed gametes. They soon become detached and float in 

 the cystic fluid near the periphery of the cyst. The centre of 

 the cyst is occupied by a granular mass of residual protoplasm, 



