bull- and pug-dogs, in the niata cattle, in sheep, in Polish fowls, short-
faced tumbler pigeons, and in one variety of the carp--for the bones of the
face to become greatly shortened. In the case of the dog, as H. Muller has
shown, this seems caused by an abnormal state of the primordial cartilage.
We may, however, readily admit that abundant and rich food supplied during
many generations would give an inherited tendency to increased size of
body, and that, from disuse, the limbs would become finer and shorter.
(3/18. Nathusius 'Die Racen des Schweines' s. 71.) We shall in a future
chapter see also that the skull and limbs are apparently in some manner
correlated, so that any change in the one tends to affect the other.

Nathusius has remarked, and the observation is an interesting one, that the
peculiar form of the skull and body in the most highly cultivated races is
not characteristic of any one race, but is common to all when improved up
to the same standard. Thus the large-bodied, long-eared, English breeds
with a convex back, and the small-bodied, short-eared, Chinese breeds with
a concave back, when bred to the same state of perfection, nearly resemble
each other in the form of the head and body. This result, it appears, is
partly due to similar causes of change acting on the several races, and
partly to man breeding the pig for one sole purpose, namely, for the
greatest amount of flesh and fat; so that selection has always tended
towards one and the same end. With most domestic animals the result of
selection has been divergence of character, here it has been convergence.
(3/19. 'Die Racen des Schweines' s. 47. 'Schweineschadel' s. 104. Compare
also the figures of the old Irish and the improved Irish breeds in
Richardson on 'The Pig' 1847.)

The nature of the food supplied during many generations has apparently
affected the length of the intestines; for, according to Cuvier (3/20.
Quoted by Isid. Geoffroy 'Hist. Nat. Gen.' tome 3 page 441.), their length