FOUNDATIONAL AGES 



ii 



theory of it was nothing less than the gradual breaking up 

 of individual self-sufficiency, and forcing the cells to work 

 more or less with one another for the common weal of the 

 colony as a whole. In other words, particular functions were 

 to be assigned to particular cells ; labour was to be divided ; 



Gastrula Stage (highly magnified). 

 The figures to the right are in section. 



egoism (for a time) was to make way for altruism; an 

 interesting datum in primitive ethics. 



The first attempt to this higher life was probably made 

 amongst colonies from which, in course of time, Sponges 

 were evolved. At one point in the colony certain cells 

 gradually lost their versatile powers and were more or less 

 drawn into the interior. As the result of continued indrawal, 

 a tube or cavity was formed, and the colony thus came to 



