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. 
“T 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 
