So, again, I was told
that the foals of cart and race-horses--breeds which have been almost
wholly formed by selection under domestication--differed as much as the
full-grown animals; but having had careful measurements made of the dams
and of three-days-old colts of race and heavy cart-horses, I find that this
is by no means the case.
As we have conclusive evidence that the breeds of the Pigeon are descended
from a single wild species, I compared the young pigeons within twelve
hours after being hatched. I carefully measured the proportions (but will
not here give the details) of the beak, width of mouth, length of nostril
and of eyelid, size of feet and length of leg, in the wild parent species,
in pouters, fantails, runts, barbs, dragons, carriers, and tumblers. Now,
some of these birds, when mature, differ in so extraordinary a manner in
the length and form of beak, and in other characters, that they would
certainly have been ranked as distinct genera if found in a state of
nature. But when the nestling birds of these several breeds were placed in
a row, though most of them could just be distinguished, the proportional
differences in the above specified points were incomparably less than in
the full-grown birds. Some characteristic points of difference--for
instance, that of the width of mouth--could hardly be detected in the
young. But there was one remarkable exception to this rule, for the young
of the short-faced tumbler differed from the young of the wild rock-pigeon,
and of the other breeds, in almost exactly the same proportions as in the
adult stage.
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