The Eggs of Birds 



443 



woods, surrounded by no nest, and are so precisely the 

 colour of the dead leaves that nothing but the merest 

 accident would lead to their discovery by the eye alone. 

 The same is eminently true of the bird itself. None of 

 the almost uncatchable hummingbirds needs to lay 

 more than two eggs in order to recruit the ranks of its 



Fig. 352. — Nest and eggs of the Anna Hummingbird. 



Species to the full quota permitted it in the numerical 

 adjustment of bird life. 



" I have gone into this matter somewhat at length, 

 though by no means exhaustively, because I am not 

 aware that the matter has ever been exploited, and be- 

 cause it embodies a general law or principle. Thus we 

 see that the nest complement of eggs of any bird is in 

 exact proportion to the average danger to which that 



