considered as monstrosities, for they are not injurious, and are strictly
inherited. The whole head is much shortened; thus, whilst in common breeds
its length to that of the body is as 1 to 6, in the "cultur-racen" the
proportion is as 1 to 9, and even recently as 1 to 11. (3/15. 'Die Racen
des Schweines' s. 70.) Figure 3 (3/16. These woodcuts are copied from
engravings given in Mr. S. Sidney's excellent edition of 'The Pig' by
Youatt 1860. See pages 1, 16, 19.) of the head of a wild boar and of a sow
from a photograph of the Yorkshire Large Breed, may aid in showing how
greatly the head in a highly cultivated race has been modified and
shortened.

Nathusius has well discussed the causes of the remarkable changes in the
skull and shape of the body which the highly cultivated races have
undergone. These modifications occur chiefly in the pure and crossed races
of the S. indicus type; but their commencement may be clearly detected in
the slightly improved breeds of the S. scrofa type. (3/17.
'Schweineschadel' s. 74, 135.) Nathusius states positively (s. 99, 103), as
the result of common experience and of his experiments, that rich and
abundant food, given during youth, tends by some direct action to make the
head broader and shorter; and that poor food works a contrary result. He
lays much stress on the fact that all wild and semi-domesticated pigs, in
ploughing up the ground with their muzzles, have,
whilst young, to exert the powerful muscles fixed to the hinder part of the
head. In highly cultivated races this habit is no longer followed, and
consequently the back of the skull becomes modified in shape, entailing
other changes in other parts. There can hardly be a doubt that so great a
change in habits would affect the skull; but it seems rather doubtful how
far this will account for the greatly reduced length of the skull and for
its concave front. It is well known (Nathusius himself advancing many
cases, s. 104) that there is a strong tendency in many domestic animals--in