104 ANIMAL INDIVIDUALITY [CH. 



of sixteen breaks away from the rest, arranges its 

 parts in the familiar way, and constitutes itself a 

 minute but perfect new colony 1 . 



Among all the other members of the family except 

 Volvox, the asexual reproduction (with which alone we 

 need here be concerned) is accomplished in a similar 

 way each cell takes upon itself to reproduce a whole 

 new colony. They are colonies and nothing more- 

 their members have united together because of certain 

 benefits resulting from mere aggregation, but are not 

 in any way interdependent, so that the wholes are 

 scarcely more than the sum of their parts. 



Though, as we have said, Volvox is obviously 

 related to Gonium and the others, it is separated 

 from them by somewhat of a gap. 



In the first place, it contains, instead of sixteen or 

 even sixty-four cells, a vast number, mounting up in 

 some species to twenty thousand (see frontispiece). 

 All these cells are inter-connected by fine strands of 

 protoplasm passing through their party-walls 2 and 

 they are arranged in a single layer on the outside of 

 a sphere whose inner parts are filled with a very fluid 

 jelly, so that the Vol vox-colony has what we may call 

 an internal medium of its own. Finally, and this is 



1 Some species of Gonium, such as that represented in Fig. 7, are 

 even simpler, being formed of but four cells. 



2 Though these connections have not been described for other 

 members of the family, it is possible that they have been overlooked. 



