. Their domesticated descendants, on the other hand, if not
separated, cross with the utmost freedom and become commingled. The several
European breeds have so often been crossed, both intentionally and
unintentionally, that, if any sterility ensued from such unions, it would
certainly have been detected. As zebus inhabit a distant and much hotter
region, and as they differ in so many characters from our European cattle,
I have taken pains to ascertain whether the two forms are fertile when
crossed. The late Lord Powis imported some zebus and crossed them with
common cattle in Shropshire; and I was assured by his steward that the
cross-bred animals were perfectly fertile with both parent-stocks. Mr.
Blyth informs me that in India hybrids, with various proportions of either
blood, are quite fertile; and this can hardly fail to be known, for in some
districts[193] the two species are allowed to breed freely together. Most
of the cattle which were first introduced into Tasmania were humped, so
that at one time thousands of crossed animals existed there; and Mr. B.
O'Neile Wilson, M.A., writes to me from Tasmania that he has never heard of
any sterility having been observed. He himself formerly possessed a herd of
such crossed cattle, and all were perfectly fertile; so much so, that he
cannot remember even a single cow failing to calve. These several facts
afford an important confirmation of the Pallasian doctrine that the
descendants of species which when first domesticated would if crossed
probably have been in some degree sterile, become perfectly fertile after a
long course of domestication. In a future chapter we shall see that this
doctrine throws much light on the difficult subject of Hybridism.

I have alluded to the cattle in Chillingham Park, which, according to
Ruetimeyer, have been very little changed from the _Bos primigenius_ type.
This park is so ancient that it is {84} referred to in a record of the year
1220. The cattle in their instincts and habits are truly wild. They are
white, with the inside of the ears reddish-brown, eyes rimmed with black,
muzzles brown, hoofs black, and horns white tipped with black. Within a
period of thirty-three years about a dozen calves were born with "brown and
blue spots upon the cheeks or necks; but these, together with any defective
animals, were always destroyed." According to Bewick, about the year 1770
some calves appeared with black ears; but these were also destroyed by t