an explanation very similar to that here given. On the
difficult question of the almost entire disappearance of organs, as in
the limbs of snakes and of some lizards, he adduces "a certain form of
correlation, which Roux calls 'the struggle of the parts in the
organism,'" as playing an important part. Atrophy following disuse is
nearly always attended by the corresponding increase of other organs:
blind animals possess more developed organs of touch, hearing, and
smell; the loss of power in the wings is accompanied by increased
strength of the legs, etc. Now as these latter characters, being useful,
will be selected, it is easy to understand that a congenital increase of
these will be accompanied by a corresponding congenital diminution of
the unused organ; and in cases where the means of nutrition are
deficient, every diminution of these useless parts will be a gain to the
whole organism, and thus their complete disappearance will, in some
cases, be brought about directly by natural selection. This corresponds
with what we know of these rudimentary organs.

It must, however, be pointed out that the non-heredity of acquired
characters was maintained by Mr. Francis Galton more than twelve years
ago, on theoretical considerations almost identical with those urged by
Professor Weismann; while the insufficiency of the evidence for their
hereditary transmission was shown, by similar arguments to those used
above and in the work of Professor Weismann already referred to (see "A
Theory of Heredity," in _Journ. Anthrop. Instit._, vol. v. pp.
343-345).]

[Footnote 201: This explanation is derived from Weismann's Theory of the
Continuity of the Germ-Plasm as summarised in _Nature_.]

[Footnote 202: See a collection of his essays under the title, _The
Origin of the Fittest: Essays on Evolution_, D. Appleton and Co. New
York. 1887.]

[Footnote 203: _Origin of the Fittest_, p. 174.]

[Footnote 204: _Ibid._ p. 29. It may be here noted that Darwin found
these theories unintelligible. In a letter to Professor E.T. Morse in
1877, he writes: "There is one point which I regret you did not make
clear in your Address, namely, what is the meaning and importance of
Professors Cope and Hyatt's views on acceleration and retardation? I
have endeavoured, and given up in despair, the attempt to grasp their
meaning" (_Life and Letters_, vol. iii. p. 233).]

[Footnote 205: _Origin of the Fittest_, p. 374.]

[Footnote 206: _Origin of the Fit