d or diminished length of the intestines, which apparently
results from changed diet, is a more remarkable case, because it is
characteristic of certain animals in their domesticated condition, and
therefore must be inherited. The complex absorbent system, the
blood-vessels, nerves, and muscles, are necessarily all modified together
with the intestines. According to Daubenton, the intestines of the domestic
cat are one-third longer than those of the wild cat of Europe; and although
this species is not the parent-stock of the domestic animal, yet, as
Isidore Geoffroy has remarked, the several species {303} of cats are so
closely allied that the comparison is probably a fair one. The increased
length appears to be due to the domestic cat being less strictly
carnivorous in its diet than any wild feline species; I have seen a French
kitten eating vegetables as readily as meat. According to Cuvier, the
intestines of the domesticated pig exceed greatly in proportionate length
those of the wild boar. In the tame and wild rabbit the change is of an
opposite nature, and probably results from the nutritious food given to the
tame rabbit.[749]

* * * * *

_Changed Habits of Life, independently of the Use or Disuse of particular
Organs._--This subject, as far as the mental powers of animals are
concerned, so blends into instinct, on which I shall treat in a future
work, that I will here only remind the reader of the many cases which occur
under domestication, and which are familiar to every one--for instance the
tameness of our animals--the pointing or retrieving of dogs--their not
attacking the smaller animals kept by man--and so forth. How much of these
changes ought to be attributed to inherited habit, and how much to the
selection of individuals which have varied in the desired manner,
irrespectively of the special circumstances under which they have been
kept, can seldom be told. We have already seen that animals may be
habituated to a changed diet; but a few additional instances may here be
given.

In the Polynesian Islands and in China the dog is fed exclusively on
vegetable matter, and the taste for this kind of food is to a certain
extent inherited.[750] Our sporting dogs will not touch the bones of game
birds, whilst other dogs devour them with greediness. In some parts of the
world sheep have been largely fed on fish. The domestic hog is fond of
barley, the wild boar is said to disdain it