VOLVOCALES 



31 



I 

 ft 



Pig. 22. Volvox. A-C, development of oospore of V. Rousseletii ( x 750). 

 OMi = outer wall. A, flagellar stage. B, mature. C, exospore formation. D— L, 

 development of daughter colony (gonidium). F, two-celled stage ( x 750). 

 G, four-celled stage ( x 750). H, eight-celled stage ( x 750). I, sixteen-celled 

 stage ( X 750). J-L, formation of phialopore ( x 225). (After Pocock.) 



