€hap. YIII. 
SEXUAL SELECTION. 
259 
are eminently variable. In the same manner as man 
can give beauty, according to his standard of taste, to his 
male poultry — can give to the Sebright bantam a new 
and elegant plumage, an erect and peculiar carriage— 
so it appears that in a state of nature female birds, by 
having long selected the more attractive males, have 
added to their beauty. No doubt this implies powers 
of discrimination and taste on the part of the female 
which will at first appear extremely improbable; but 
I hope hereafter to shew that this is not the case. 
From our ignorance on several points, the precise 
manner in which sexual selection acts is to a certain 
extent uncertain. Nevertheless if those naturalists who 
already believe in the mutability of species, will read 
the following chapters, they will, I think, agree with 
me that sexual selection has played an important part 
in the history of the organic world. It is certain that 
with almost all animals there is a struggle between the 
males for the possession of the female. This fact is so 
notorious that it would be superfluous to give instances. 
Hence the females, supposing that their mental capacity 
sufficed for the exertion of a choice, could select one out 
of several males. But in numerous cases it appears as 
if it had been specially arranged that there should be 
a struggle between many males. Thus with migratory 
birds, the males generally arrive before the females at 
their place of breeding, so that many males are ready 
to contend for each female. The bird-catchers assert 
that this is invariably the case with the nightingale 
and blackcap, as I am informed by Mr. Jenner Weir, 
who confirms the statement with respect to the latter 
species. 
Mr. Swaysland of Brighton, who has been in the habit, 
during the last forty years, of catching our migratory 
birds on their first arrival, writes to me that he has 
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