SPH.^KOMYXA AND CEEATOMYXA 



731 



development to two spores. The process of spore formation is very similar 

 to that of M. pfeifferi, but the spores are very dilrerent in character. The 

 infective amoeboid body in the fully-formed spore has at first two nuclei, 

 but these fuse, so that the final infective agent has a single nucleus. During 

 spore formation the parasite continues to increase in size, while nuclear 

 multiplication is going on. Each parasite produces a large number of 

 spores, which in any individual are in various stages of development. 



Fig. 310. — Ceratomyxa dreimnopsettce (xca. 700). (After Awerinzew, 1909.) 



. Parasite with two vegetative nuclei and a macrogametocyte and microgametocyte. 



. Similar form in which the gametocytes have divided into two macrogametes and two 



microgametes. C. Similar form after conjugation of the gametes. 



. Each zygote has given rise to six cells. E. Each grouji of six cells is producing a spore. 



. Single sjjore nearing maturity. G. More advanced stage of development of two spores. 



Ceratomyxa drepanopsettae Awerinzew, 1909. — This parasite was 

 discovered by Awerinzew (1909) in the gall bladder of the plaice {Drepa- 

 nopsetta platessoides), where it lives as an amoeboid organism. At first 

 the trophozoite has two nuclei, and it was concluded by Awerinzew that 

 this stage resulted from nuclear division of a uninucleate form. In view 

 of the subsequent conjugation process, Minchin (1912) concluded that it 

 was more probable that union of two uninucleate forms had taken place. 



