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 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 unchanged conditions, and
whilst kept in a considerable body, so that free intercrossing might
check, by blending together, any slight deviations of 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 almost infinite number of
generations, would be opposed to all experience.
Pages:
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35