s* -b. 



276 SOME MINUTE ANIMAL PARASITES 



is at the same time growing, and thus causing the 



cyst, as a whole, to increase in size. 



The pansporoblasts (Fig. 54) at first are single 



masses of cyto- 

 plasm, each with 

 a nucleus, but 

 they soon differ- 

 entiate to form 

 spores. The 

 youngest pan- 

 sporoblasts are 

 still uninucleate 

 G. (Fig. 54, 6), but 

 those of the in- 

 termediate zone 

 (Fig. 54, c) soon 

 i-;i show first one or 



_. r ^^P-C(. two, then four 



or more spores ; 

 while in the 

 oldest pansporo- 

 blasts (Fig. 54, d) 

 about a dozen 

 closely packed 



F IGt 54 RHINOSPORIDIUM : PORTION OF A Spores(Flg.54>^) 

 FULLY DEVELOPED CYST can be found. 



a, Cyst wall ; b, young pansporoblasts in When the cysts 

 peripheral zone ; c, intermediate zone of J 



pansporoblasts ; d, central zone of fully- nave reached a 

 developed spore morulae, and spores; e, certa i n s i ze , the 

 spore ; /, nucleus of spore 



growth of the 



peripheral protoplasm ceases, and as a result, no 

 more pansporoblasts are formed. Each fully de- 





