re, whether useful or
injurious to the individual, has been shown in the first part; so that
we need feel no surprise at these truly abortive parts becoming
hereditary. A curious instance of the force of hereditariness is
sometimes seen in two little loose hanging horns, quite useless as far
as the function of a horn is concerned, which are produced in hornless
races of our domestic cattle{498}. Now I believe no real distinction can
be drawn between a stump representing a tail or a horn or the
extremities; or a short shrivelled stamen without any pollen; or a
dimple in a petal representing a nectary, when such rudiments are
regularly reproduced in a race or family, and the true abortive organs
of naturalists. And if we had reason to believe (which I think we have
not) that all abortive organs had been at some period _suddenly_
produced during the embryonic life of an individual, and afterwards
become inherited, we should at once have a simple explanation of the
origin of abortive and rudimentary organs{499}. In the same manner as
during changes of pronunciation certain letters in a word may become
useless{500} in pronouncing it, but yet may aid us in searching for its
derivation, so we can see that rudimentary organs, no longer useful to
the individual, may be of high importance in ascertaining its descent,
that is, its true classification in the natural system.

{496} _Origin_, Ed. i. p. 454, vi. p. 625.

{497} In the _Origin_, Ed. i. p. 454, vi. p. 625, the author in
referring to semi-monstrous variations adds "But I doubt whether
any of these cases throw light on the origin of rudimentary organs
in a state of nature." In 1844 he was clearly more inclined to an
opposite opinion.

{498} _Origin_, Ed. i. p. 454, vi. p. 625.

{499} See _Origin_, Ed. i. p. 454, vi. p. 625. The author there
discusses monstrosities in relation to rudimentary organs, and
comes to the conclusion that disuse is of more importance, giving
as a reason his doubt "whether species under nature ever undergo
abrupt changes." It seems to me that in the _Origin_ he gives more
weight to the "Lamarckian factor" than he did in 1844. Huxley took
the opposite view, see the Introduction.

{500} _Origin_, Ed. i. p. 455, vi. p. 627.

_Abortion from gradual disuse._

There seems to be some probability that continued disuse of any part or
organ, and the selection of individuals