As nearly all our animals were domesticated at an extremely remote epoch, we
cannot, of course, say whether they varied quickly or slowly when first
subjected to new conditions. But Dr. Bachman (22/29. 'Examination of the
Characteristics of Genera and Species' Charleston 1855 page 14.) states that
he has seen turkeys raised from the eggs of the wild species lose their
metallic tints and become spotted with white in the third generation. Mr.
Yarrell many years ago informed me that the wild ducks bred on the ponds in
St. James's Park, which had never been crossed, as it is believed, with
domestic ducks, lost their true plumage after a few generations. An excellent
observer (22/30. Mr. Hewitt 'Journal of Hort.' 1863 page 39.), who has often
reared ducks from the eggs of the wild bird, and who took precautions that
there should be no crossing with domestic breeds, has given, as previously
stated, full details on the changes which they gradually undergo. He found
that he could not breed these wild ducks true for more than five or six
generations, "as they then proved so much less beautiful. The white collar
round the neck of the mallard became much broader and more irregular, and
white feathers appeared in the ducklings' wings." They increased also in size
of body; their legs became less fine, and they lost their elegant carriage.
Fresh eggs were then procured from wild birds; but again the same result
followed. In these cases of the duck and turkey we see that animals, like
plants, do not depart from their primitive type until they have been subjected
during several generations to domestication. On the other hand, Mr. Yarrell
informed me that the Australian dingos, bred in the Zoological Gardens, almost
invariably produced in the first generation puppies marked with white and
other colours; but, these introduced dingos had probably been procured from
the natives, who keep them in a semi-domesticated state. It is certainly a
remarkable fact that changed conditions should at first produce, as far as we
can see, absolutely no effect; but that they should subsequently cause the
character of the species to change. In the chapter on pangenesis I shall
attempt to throw a little light on this fact.
Public-domain text, read in full here on John Shaqi.
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