WORMS AND CCELENTERATA 287 



Symbiosis exhibits an entirely new side of natural 

 selection to us. In this case the principle that seems to 

 be the foundation of all life, the struggle of all against 

 all and the crushing • of one organism by another, is 

 thrust aside. Symbiosis teaches us the omnipotence of 

 natural selection more clearly than any other phenomenon 

 in nature. 



