• ).)4 



BIOLOGY OF THE PROTOZOA 



give rise to the speculating individuals. .The phenomena of specula- 

 tion diti'er widely but there is still much uncertainty in the diff rent 

 accounts at hand. Id some cases the trophozoites are said to pro- 

 duce pansporoblasts as in Myxosporidia during the continued vege- 

 tative life of the individual (Polysporea). Such cases, included 

 formerly under the name Blastogenea, are regarded as very doubtful 



Fig. 223. — Thelohania legeri, life cycle. A, Early stages of sporozoite after leaving 

 the spore S; B, formation of binucleated individuals; C, repeated binary division; 

 D, fusion of the two nuclei to form the sporont; E to H, nuclear and cell divisions 

 to form eight sporoblasts each of which forms one spore. (After Kudo.) 



by Doflein. In other cases the trophozoite (pansporoblast?) breaks 

 up into numerous sporulating cells, each of which produces one or 

 more spores (Oligosporea) and in still other cases the entire indi- 

 vidual forms a single spore without pansporoblast formation (Mono- 

 sporea). The absence of pansporoblasts in such cases is regarded 

 as evidence of extreme adaptation on the part of the exclusively 

 cytozoic parasites (Nosema species). 



