90 



OUTLINES OF EVOLUTIONARY BIOLOGY 



different sizes. It is probable that we have here a kind of 

 foreshadowing of that sharp differentiation into large (female) 



megagametes and small (male) microgametes of which we have 

 already spoken. 



In Eudorina, which forms colonies somewhat similar to those of 

 Pandorina, this differentiation is already fully expressed (Fig. 40). 

 The megagametes or ova 1 differ scarcely at all from ordinary 



1 Often termed by botanists oospheres. 



