Neither the peacock, a native of the same country,
nor the guinea-fowl, an inhabitant of the dry deserts of Africa, has varied
at all, or only in colour. The turkey, from Mexico, has varied but little.
The duck, on the other hand, a native of Europe, has yielded some
well-marked races; and as this is an aquatic bird, it must have been
subjected to a far more serious change in its habits than the pigeon or
even the fowl, which nevertheless have varied in a much higher degree. The
goose, a native of Europe and aquatic like the duck, has varied less than
any other domesticated bird, except the peacock.

Bud-variation is, also, important under our present point of view. In some
few cases, as when all the eyes or buds on the same tuber of the potato, or
all the fruit on the same plum-tree, or all the flowers on the same plant,
have suddenly varied in the same manner, it might be argued that the {288}
variation had been definitely caused by some change in the conditions to
which the plants had been exposed; yet, in other cases, such an admission
is extremely difficult. As new characters sometimes appear by
bud-variation, which do not occur in the parent-species or in any allied
species, we may reject, at least in these cases, the idea that they are due
to reversion. Now it is well worth while to reflect maturely on some
striking case of bud-variation, for instance that of the peach. This tree
has been cultivated by the million in various parts of the world, has been
treated differently, grown on its own roots and grafted on various stocks,
planted as a standard, against a wall, and under glass; yet each bud of
each sub-variety keeps true to its kind. But occasionally, at long
intervals of time, a tree in England, or under the widely-different climate
of Virginia, produces a single bud, and this yields a branch which ever
afterwards bears nectarines. Nectarines differ, as every one knows, from
peaches in their smoothness, size, and flavour; and the difference is so
great, that some botanists have maintained that they are specifically
distinct. So permanent are the characters thus suddenly acquired, that a
nectarine produced by bud-variation has propagated itself by seed. To guard
against the supposition that there is some fundamental distinction between
bud and seminal variation, it is well to bear in mind that nectarines have
likewise been produced from the stone of the peach; and, reversely, peaches
from the stone of the nect