The Origin of Mimicry 
It is easy to understand the profit that these 
mimics derive from their mimicry. When once 
the disguise has been assumed we can compre- 
hend how natural selection will tend to improve 
it by eliminating those that mimic badly; but it 
seems to us that the theory fails utterly to 
account for the origin of the likeness. 
13. Similarly, the Neo- Darwinian theory fails to 
explain the colours of the eggs of birds laid in 
open nests, why, for example, the eggs of the 
accentor or hedge-sparrow are blue and those 
of the doves are white. 
14. The theory fails to give a satisfactory ex- 
planation of the phenomena of sexual dimorphism. 
Why, for example, in some species of doves and 
ducks, thesexes are alike, while in other species 
with similar habits they differ in appearance. 
15. It fails to explain why the rook is black and 
why the jackdaw has a grey neck. 
These and many other objections we shall 
deal with more fully in the chapter on animal 
colouration. It must suffice here to mention 
them, and to say that our experience teaches us 
that scarcely a single species of bird or: beast 
exists which does not display some characteristic 
which is inexplicable on the theory that natural 
selection, acting on small variations, is the one 
and only cause of organic evolution. 
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