losely allied difficulty consequent on the doctrine
of the descent of our domestic dogs from several wild species, namely, that
they do not seem to be perfectly fertile with their supposed parents. But
the experiment has not been quite fairly tried; the Hungarian dog, for
instance, {32} which in external appearance so closely resembles the
European wolf, ought to be crossed with this wolf; and the pariah-dogs of
India with Indian wolves and jackals; and so in other cases. That the
sterility is very slight between certain dogs and wolves and other Canidae
is shown by savages taking the trouble to cross them. Buffon got four
successive generations from the wolf and dog, and the mongrels were
perfectly fertile together.[51] But more lately M. Flourens states
positively as the result of his numerous experiments that hybrids from the
wolf and dog, crossed _inter se_, become sterile at the third generation,
and those from the jackal and dog at the fourth generation.[52] But these
animals were closely confined; and many wild animals, as we shall see in a
future chapter, are rendered by confinement in some degree or even utterly
sterile. The Dingo, which breeds freely in Australia with our imported
dogs, would not breed though repeatedly crossed in the Jardin des
Plantes.[53] Some hounds from Central Africa, brought home by Major Denham,
never bred in the Tower of London;[54] and a similar tendency to sterility
might be transmitted to the hybrid offspring of a wild animal. Moreover, it
appears that in M. Flourens' experiments the hybrids were closely bred in
and in for three or four generations; but this circumstance, although it
would almost certainly increase the tendency to sterility, would hardly
account for the final result, even though aided by close confinement,
unless there had been some original tendency to lessened fertility. Several
years ago I saw confined in the Zoological Gardens of London a female
hybrid from an English dog and jackal, which even in this the first
generation was so sterile that, as I was assured by {33} her keeper, she
did not fully exhibit her proper periods; but this case, from the numerous
instances of fertile hybrids from these two animals, was certainly
exceptional. In almost all experiments on the crossing of animals there are
so many causes of doubt, that it is extremely difficult to come to any
positive conclusion. It would, however, appear, that those who believe that
our dogs are descended