MYXOSPORIDIA. 



331 



and in the family Myxobolidse an iodinophilous vacuole 

 containing glycogenous substance which stains mahogany- 

 red with iodine. 



When introduced into the digestive tract of a fish, the 

 sporoplasm leaves the spore as amoeboid " planonts " or 

 wanderers. These probably fuse together and grow into the 

 characteristic trophic phase, the so-called multinucleate 

 Plasmodium. Passing through the epithelium of the gut, 

 it enters the tissues of specified organs, grows into a schizont, 

 and its nucleus divides repeatedly. Some of the nuclei 

 become surrounded by cytoplasm and form sporonts. The 

 sporont may be monosporous, disporous or polysporous, 

 according as it produces one, two or many spores. 



Fig. 165.- — Development of the spore from the pansporoblast inMyxobolus 

 pfeifferi Thelohan. A, single propagative cell from multi- 

 nucleate Plasmodium ; B, division to form one large and 

 one small cell ; G, association of two pairs to form a group 

 of two large and two small cells ; D, formation of six- 

 celled stage ; E, stage with fourteen nuclei, two of which 

 are the nuclei of the original small cells ; F, division into 

 two bodies, each with six nuclei, while the nuclei of the small 

 cells take up a position at the angles between them ; 

 G, each sporoblast now divides into three cells, two of which, 

 each with a single nucleus and a vacuole, are the capsulo- 

 genoiis cells containing the polar capsules, one with two 

 nuclei forms the binucleate amcebula, while the remaining 

 two nuclei become peripherally arranged and form, together 

 with some cytoplasm, the valves of the spore ; H, more 

 advanced stage of one of the developing spores ; /, J fully 

 developed spores. (From Wenyon, after Keysselitz.) 



