erently circumstanced, individuals of the same species, having
slightly different constitutions or structure, would often succeed
better in the one country than in the other, and thus by a process of
"natural selection," as will hereafter be more fully explained, two
sub-breeds might be formed. This, perhaps, partly explains what has been
remarked by some authors, namely, that the varieties kept by savages
have more of the character of species than the varieties kept in
civilised countries.

On the view here given of the all-important part which selection by
man has played, it becomes at once obvious, how it is that our domestic
races show adaptation in their structure or in their habits to man's
wants or fancies. We can, I think, further understand the frequently
abnormal character of our domestic races, and likewise their differences
being so great in external characters and relatively so slight in
internal parts or organs. Man can hardly select, or only with much
difficulty, any deviation of structure excepting such as is externally
visible; and indeed he rarely cares for what is internal. He can never
act by selection, excepting on variations which are first given to
him in some slight degree by nature. No man would ever try to make
a fantail, till he saw a pigeon with a tail developed in some slight
degree in an unusual manner, or a pouter till he saw a pigeon with a
crop of somewhat unusual size; and the more abnormal or unusual any
character was when it first appeared, the more likely it would be to
catch his attention. But to use such an expression as trying to make a
fantail, is, I have no doubt, in most cases, utterly incorrect. The man
who first selected a pigeon with a slightly larger tail, never dreamed
what the descendants of that pigeon would become through long-continued,
partly unconscious and partly methodical selection. Perhaps the parent
bird of all fantails had only fourteen tail-feathers somewhat expanded,
like the present Java fantail, or like individuals of other and distinct
breeds, in which as many as seventeen tail-feathers have been counted.
Perhaps the first pouter-pigeon did not inflate its crop much more than
the turbit now does the upper part of its oesophagus,--a habit which
is disregarded by all fanciers, as it is not one of the points of the
breed.

Nor let it be thought that some great deviation of structure would
be necessary to catch the fancier's eye: he perceives extremely small