stocks. Hence it has been argued that no deductions can be drawn from
domestic races to species in a state of nature. I have in vain endeavoured
to discover on what decisive facts the above statement has so often and so
boldly been made. There would be great difficulty in proving its truth:
we may safely conclude that very many of the most strongly marked domestic
varieties could not possibly live in a wild state. In many cases we do not
know what the aboriginal stock was, and so could not tell whether or not
nearly perfect reversion had ensued. It would be necessary, in order to
prevent the effects of intercrossing, that only a single variety should be
turned loose in its new home. Nevertheless, as our varieties certainly do
occasionally revert in some of their characters to ancestral forms, it
seems to me not improbable that if we could succeed in naturalising, or
were to cultivate, during many generations, the several races, for
instance, of the cabbage, in very poor soil--in which case, however, some
effect would have to be attributed to the DEFINITE action of the poor soil
--that they would, to a large extent, or even wholly, revert to the wild
aboriginal stock. Whether or not the experiment would succeed is not of
great importance for our line of argument; for by the experiment itself the
conditions of life are changed. If it could be shown that our domestic
varieties manifested a strong tendency to reversion--that is, to lose their
acquired characters, while kept under the same conditions and while kept in
a considerable body, so that free intercrossing might check, by blending
together, any slight deviations in their structure, in such case, I grant
that we could deduce nothing from domestic varieties in regard to species.
But there is not a shadow of evidence in favour of this view: to assert
that we could not breed our cart and race-horses, long and short-horned
cattle, and poultry of various breeds, and esculent vegetables, for an
unlimited number of generations, would be opposed to all experience.

CHARACTER OF DOMESTIC VARIETIES; DIFFICULTY OF DISTINGUISHING BETWEEN