249] STUDIES ON GREGARINES— WATSON 39 



lost and the result is a body twice the size of the original gamete, with 

 a nuclear content made up of the fusion of that of the two gametes. This 

 larger body, which in staining reaction is identical with that of the 

 gametes, is the zygote. In a cyst of twenty-four hours, no spore ducts 

 had begun to appear but the cyst was full of zygotes. 



The zygotes when fully formed are ellipsoidal in shape, contain 

 many small deeply staining bodies, and possess a rather thin wall (Fig. 

 234). They develop gradually into spores. The outline becomes more 

 spore-like by the gradual flattening of the ends and the decrease in the 

 number of chromidia while the outer wall increases in thickness. In a 

 cyst of about thirty hours the zygotes have attained the shape of the ripe 

 spores but the content is still that characteristic of the zygote. 



From the thirtieth hour on, the chromidia rearrange themselves 

 and decrease in number by fusion, and the perfection of the mechanism 

 for expelling the ripe spores proceeds. 



It is probable that the cyst can develop and spores be expelled 

 while within the intestine, possibly resulting in the reinfection of the 

 host and accounting for the enormous numbers of parasites found in 

 some hosts. I have seen cysts dense and opaque, cysts pearl gray and 

 mottled, and even cysts with spore ducts well developed and nine in 

 number, all within the body of a freshly caught cricket. The same ad- 

 vanced stages of the cysts of another species have been found in the 

 bodies of freshly opened locusts and also in certain Crustacea. 



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