offspring by the sire of another
breed.

{263} This section corresponds roughly to that on _Hybrids and
Mongrels compared independently of their fertility_, _Origin_, Ed.
i. p. 272, vi. p. 403. The discussion on Gaertner's views, given in
the _Origin_, is here wanting. The brief mention of prepotency is
common to them both.

{264} See _Animals and Plants_, Ed. ii. vol. I. p. 435. The
phenomenon of _Telegony_, supposed to be established by this and
similar cases, is now generally discredited in consequence of
Ewart's experiments.

_Summary of second chapter_{265}.

{265} The section on p. 109 is an appendix to the summary.

Let us sum up this second chapter. If slight variations do occur in
organic beings in a state of nature; if changes of condition from
geological causes do produce in the course of ages effects analogous to
those of domestication on any, however few, organisms; and how can we
doubt it,--from what is actually known, and from what may be presumed,
since thousands of organisms taken by man for sundry uses, and placed
in new conditions, have varied. If such variations tend to be
hereditary; and how can we doubt it,--when we see shades of expression,
peculiar manners, monstrosities of the strangest kinds, diseases, and a
multitude of other peculiarities, which characterise and form, being
inherited, the endless races (there are 1200 kinds of cabbages{266}) of
our domestic plants and animals. If we admit that every organism
maintains its place by an almost periodically recurrent struggle; and
how can we doubt it,--when we know that all beings tend to increase in a
geometrical ratio (as is instantly seen when the conditions become for a
time more favourable); whereas on an average the amount of food must
remain constant, if so, there will be a natural means of selection,
tending to preserve those individuals with any slight deviations of
structure more favourable to the then existing conditions, and tending
to destroy any with deviations of an opposite nature. If the above
propositions be correct, and there be no law of nature limiting the
possible amount of variation, new races of beings will,--perhaps only
rarely, and only in some few districts,--be formed.

{266} I do not know the authority for this statement.

_Limits of Variation._

That a limit to variation does exist in nature is assumed by most
authors, though I am unable to discove