CNIDOSPORIDIA, MYXOSPORIDIA 



455 



Fig. 208. Sporogony in Myxosoma catostomi, X2130 (Kudo). 

 a, sporont or pansporoblast; b-h, development of two sporoblasts 

 within the sporont; i, a nearly mature spore; j-1, views of spore. 



narily referred to as a myxosporidian cyst. If the site of infection 

 is near the body surface, the large cyst breaks and the mature 

 spores become set free in the water. In case the infection is con- 

 fined to internal organs, the spores will not be set free while the 

 host fish lives. Upon its death and disintegration of the body, 

 however, the liberated spores become the source of new infection. 



The more primitive Myxosporidia are coelozoic in the host's 

 organs, such as the gall bladder, uriniferous tubules of the kid- 

 ney, urinary bladder, etc. In these forms, the liberated amoebulae 

 make their way into the specific organ and there grow into multi- 

 nucleate amoeboid trophozoites which are capable of forming 

 pseudopodia of various types. They multiply by exogenous or en- 

 dogenous budding or plasmotomy. One to several spores are de- 

 veloped in the trophozoite. 



Almost all observes agree in maintaining the view that the 2 

 nuclei of the sporoplasm or 2 uninucleate sporoplasms fuse into 

 one (autogamy or paedogamy), but as to the nuclear as well as 



