144 



GENERAL BIOLOGY 



free individuals, each of which secretes a gelatinous 

 sphere and by successive divisions gives rise to a new 

 eight-celled colony. 



Anisogamy. A further advantage would accrue 

 to the species that developed microgametes, in 



FIG. 55. Stephana sphcer a, a colonial flagellate which reproduces by 

 isogamy : A, a mature 8-celled colony in equatorial view ; B, a colony 

 whose individuals by repeated divisions have formed daughter-colonies 

 within the mother colony ; C, a colony, whose individuals by repeated 

 divisions have formed flagellated individuals that function as gametes ; 

 Z), single gamete on a larger scale ; G to L, stages in the process of con- 

 jugation. (From Hertwig.) 



comparison with one that did not, in that the larger 

 number of individuals so produced would be more 

 active on account of their smaller size, and therefore, 



