Not a member?     Existing members login below:
Take Free-eBooks to GO! With our Mobile Apps here

The Variation of Animals and Plants

or "sport," which tends at all times and in many places to reappear. This view is
supported by the young being at first white like the young of the white breed, which is
undoubtedly a variation. If, on the other hand, we believe the japanned peacock to be a
distinct species, we must suppose that in all the above cases the common breed had at
some former period been crossed by it, but had lost every trace of the cross; yet that the
offspring of these birds suddenly and completely reacquired through reversion the
characters of P. nigripennis. I have heard of no other such case in the animal or vegetable
kingdom. To perceive the full improbability of such an occurrence, we may suppose that
a breed of dogs had been crossed at some former period with a wolf, but had lost every
trace of the wolf-like character, yet that the breed gave birth in seven instances in the
same country, within no great length of time, to a wolf perfect in every character; and we
must further suppose that in two of the cases, the newly produced wolves afterwards
spontaneously increased to such an extent as to lead to the extinction of the parent breed
of dogs. So remarkable a bird as the P. nigripennis, when first imported, would have
realised a large price; it is therefore improbable that it should have been silently
introduced and its history subsequently lost. On the whole the evidence seems to me, as it
did to Sir R. Heron, to be decisive in favour of the japanned or black-shouldered breed
being a variation, induced by some unknown cause. On this view, the case is the most
remarkable one ever recorded of the abrupt appearance of a new form, which so closely
resembles a true species that it has deceived one of the most experienced of living
It seems fairly well established by Mr. Gould, that the turkey, in accordance with the
history of its first introduction, is descended from a wild Mexican form, which had been
domesticated by the natives before the discovery of America, and which is now generally
ranked as a local race, and not as a distinct species. However this may be, the case
deserves notice because in the United States wild male turkeys sometimes court the
domestic hens, which are descended from the Mexican form, "and are generally received
by them with great pleasure." Several accounts have likewise been published of young
birds, reared in the United States from the eggs of the wild species, crossing and
commingling with the common breed. In England, also, this same species has been kept
in several parks; from two of which the Rev. W. D. Fox procured birds, and they crossed
freely with the common domestic kind, and during many years afterwards, as he informs
me, the turkeys in his neighbourhood clearly showed traces of their crossed parentage.
We here have an instance of a domestic race being modified by a cross with a distinct
wild race or species. F. Michaux suspected in 1802 that the common domestic turkey was
not descended from the United States species alone, but likewise from a southern form,
and he went so far as to believe that English and French turkeys differed from having
different proportions of the blood of the two parent-forms.
English turkeys are smaller than either wild form. They have not varied in any great
degree; but there are some breeds which can be distinguished as Norfolks, Suffolks,
Whites, and Copper-coloured (or Cambridge), all of which, if precluded from crossing
with other breeds propagate their kind truly. Of these kinds, the most distinct is the small,