ation
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
Columbidae, 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 years in several
quarters of the world; the earliest known record of pigeons is in the
fifth Aegyptian dynasty, about 3000 B.C., as was pointed out to me by
Professor Lepsius; but Mr. Birch informs me that pigeons are give