ity, and not to
its primary cause, which may have acted on the ovules or male element; in
nearly the same manner as in the crossed offspring from a short-horned cow
by a long-horned bull, the greater length of horn, though appearing late in
life, is clearly due to the male element.

Having alluded to the subject of reversion, I may here refer to a statement
often made by naturalists--namely, that our domestic varieties, when run
wild, gradually but certainly revert in character to their aboriginal
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 quite 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 {15} 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 direct 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, whilst kept under the same conditions, and
whilst 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