and that some degree of selection has been requisite to keep them true. It
is almost certain that abundant food given during many generations directly
affects the size of a breed. (3/68. Low 'Domesticated Animals of the
British Isles' page 264.) That climate directly affects the thickness of
the skin and the hair is likewise certain: thus Roulin asserts (69 'Mem. de
l'Institut present. Par divers Savans' tome 6 1835 page 332.) that the
hides of the feral cattle on the hot Llanos "are always much less heavy
than those of the cattle raised on the high platform of Bogota; and that
these hides yield in weight and in thickness of hair to those of the cattle
which have run wild on the lofty Paramos." The same difference has been
observed in the hides of the cattle reared on the bleak Falkland Islands
and on the temperate Pampas. Low has remarked (3/70. Idem pages 304, 368
etc.) that the cattle which inhabit the more humid parts of Britain have
longer hair and thicker skins than other British cattle. When we compare
highly improved stall-fed cattle with the wilder breeds, or compare
mountain and lowland breeds, we cannot doubt that an active life, leading
to the free use of the limbs and lungs, affects the shape and proportions
of the whole body. It is probable that some breeds, such as the semi-
monstrous niata cattle, and some peculiarities, such as being hornless,
etc., have appeared suddenly owing to what we may call in our ignorance
spontaneous variation; but even in this case a rude kind of selection is
necessary, and the animals thus characterised must be at least partially
separated from others. This degree of care, however, has sometimes been
taken even in little-civilised districts, where we should least have
expected it, as in the case of the niata, chivo, and hornless cattle in S.
America.

That methodical selection has done wonders within a recent period in
modifying our cattle, no one doubts. During the process of methodical
selection it has occasionally happened that deviations of structure, more