e chief Races._

We will now consider more closely the probable steps by which the chief
races have been formed. As long as pigeons are kept semi-domesticated in
dovecots in their native country, without any care in selecting and
matching them, they are liable to little more variation than the wild _C.
livia_, namely, in the wings becoming chequered with black, in the croup
being blue or white, and in the size of the body. When, however,
dovecot-pigeons are transported into diversified countries, such as Sierra
Leone, the Malay archipelago, and Madeira (where the wild _C. livia_ is not
known to exist), they are exposed to new conditions of life; and apparently
in consequence they vary in a somewhat greater degree. When closely
confined, either for the pleasure of watching them, or to prevent their
straying, they must be exposed, even under their native climate, to {213}
considerably different conditions; for they cannot obtain their natural
diversity of food; and, what is probably more important, they are
abundantly fed, whilst debarred from taking much exercise. Under these
circumstances we might expect to find, from the analogy of all other
domesticated animals, a greater amount of individual variability than with
the wild pigeon; and this is the case. The want of exercise apparently
tends to reduce the size of the feet and organs of flight; and then, from
the law of correlation of growth, the beak apparently becomes affected.
From what we now see occasionally taking place in our aviaries, we may
conclude that sudden variations or sports, such as the appearance of a
crest of feathers on the head, of feathered feet, of a new shade of colour,
of an additional feather in the tail or wing, would occur at rare intervals
during the many centuries which have elapsed since the pigeon was first
domesticated. At the present day such "sports" are generally rejected as
blemishes; and there is so much mystery in the breeding of pigeons that, if
a valuable sport did occur, its history would often be concealed. Before
the last hundred and fifty years, there is hardly a chance of the history
of any such sport having been recorded. But it by no means follows from
this that such sports in former times, when the pigeon had undergone much
less variation, would have been rejected. We are profoundly ignorant of the
cause of each sudden and apparently spontaneous variation, as well as of
the infinitely numerous shades of difference between th