e
increased use or disuse of parts has had a more marked influence;" and
he gives as instances the changed relative weights of the wing bones and
leg bones of the wild duck and the domestic duck, "the great and
inherited development of the udders in cows and goats," and the drooping
ears of various domestic animals. Here are other passages taken from the
latest edition of the work.

"I think there can be no doubt that use in our domestic animals has
strengthened and enlarged certain parts, and disuse diminished
them; and that such modifications are inherited" (p. 108). [And on
the following pages he gives five further examples of such
effects.] "Habit in producing constitutional peculiarities and use
in strengthening and disuse in weakening and diminishing organs,
appear in many cases to have been potent in their effects" (p.
131). "When discussing special cases, Mr. Mivart passes over the
effects of the increased use and disuse of parts, which I have
always maintained to be highly important, and have treated in my
'Variation under Domestication' at greater length than, as I
believe, any other writer" (p. 176). "Disuse, on the other hand,
will account for the less developed condition of the whole inferior
half of the body, including the lateral fins" (p. 188). "I may give
another instance of a structure which apparently owes its origin
exclusively to use or habit" (p. 188). "It appears probable that
disuse has been the main agent in rendering organs rudimentary"
(pp. 400-401). "On the whole, we may conclude that habit, or use
and disuse, have, in some cases, played a considerable part in the
modification of the constitution and structure; but that the
effects have often been largely combined with, and sometimes
overmastered by, the natural selection of innate variations" (p.
114).

In his subsequent work, _The Variation of Animals and Plants under
Domestication_, where he goes into full detail, Mr. Darwin gives more
numerous illustrations of the inherited effects of use and disuse. The
following are some of the cases, quoted from volume i of the first
edition.

Treating of domesticated rabbits, he says:--"the want of exercise
has apparently modified the proportional length of the limbs in
comparison with the body" (p. 116). "We thus see that the most
important and complicated organ [