2OO 



ANIMAL LIFE 



as we review each group in its response to the welfare 

 of the race. 



The most majestic of these responses is that of 



FIG. 35. Transformation of a groundling Sea- worm (Nereis), A, into a 

 migrant of pelagic waters. B, The eyes are enlarged, the paddles more 

 complex and effective. (After Quatrefages.) 



migration. Under the stress of a cause not their 

 own, birds and -fish assume a new aspect and travel 

 with their mates to far-off, traditional nesting-places. 

 On this journey they behave as creatures possessed. 



