Aquatic Adaptations of Insect Larvce 281 



In quickly growing animals no larger than insects 

 these matters are very important ; for even a small and 

 transient food supply ma}^ serve for the nurture of a 

 brood of larvae. And if the food supply be exhausted 

 in one place, or if other conditions fail there, the adults 

 may fly elsewhere to lay their eggs. The facts of 

 dominance would seem to justify this explanation, since 

 those groups that most abound in the world to-day are 

 in general the ones in which metamorphosis is most 

 complete and in which the power of flight is best 

 developed. 



