observations, purposely made on the most distinct breeds. Now, it is
difficult, perhaps impossible, to bring forward one case of the hybrid
offspring of two animals _clearly distinct_ being themselves perfectly
fertile. Some authors believe that long-continued domestication
eliminates this strong tendency to sterility: from the history of the
dog I think there is some probability in this hypothesis, if applied to
species closely related together, though it is unsupported by a single
experiment. But to extend the hypothesis so far as to suppose that
species, aboriginally as distinct as carriers, tumblers, pouters, and
fantails now are, should yield offspring perfectly fertile, _inter se_,
seems to me rash in the extreme.
From these several reasons, namely, the improbability of man having
formerly got seven or eight supposed
species of pigeons to breed freely under domestication; these supposed
species being quite unknown in a wild state, and their becoming nowhere
feral; these species having very abnormal characters in certain
respects, as compared with all other Columbid , though so like in most
other respects to the rock-pigeon; the blue colour and various marks
occasionally appearing in all the breeds, both when kept pure and when
crossed; the mongrel offspring being perfectly fertile; from these
several reasons, taken together, I can feel no doubt that all our
domestic breeds have descended from the Columba livia with its
geographical sub-species.
In favour of this view, I may add, firstly, that C. livia, or the
rock-pigeon, has been found capable of domestication in Europe and in
India; and that it agrees in habits and in a great number of points of
structure with all the domestic breeds. Secondly, although an English
carrier or short-faced tumbler differs immensely in certain characters
from the rock-pigeon, yet by comparing the several sub-breeds of these
breeds, more especially those brought from distant countries, we can
make an almost perfect series between the extremes of structure.
Thirdly, those characters which are mainly distinctive of each breed,
for instance the wattle and length of beak of the carrier, the
shortness of that of the tumbler, and the number of tail-feathers in
the fantail, are in each breed eminently variable; and the explanation
of this fact will be obvious when we come to treat of selection.
Fourthly, pigeons have been watched, and tended with the utmost care,
and loved by many people. They have been domesticated for thousands of
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