in very rare instances. The silver fox of North America is the only
species recorded to have bred in the Zoological Gardens of London;
the European fox has never been known to breed in captivity. Then,
again, the fox is not a sociable animal. We never hear of foxes
uniting in a pack, as do the wolves, the jackals, and the wild dogs.
Apart from other considerations, a fox may be distinguished from a
dog, without being seen or touched, by its smell. No one can produce
a dog that has half the odour of Reynard, and this odour the dog-fox
would doubtless possess were its sire a fox-dog or its dam a vixen.

Whatever may be said concerning the difference existing between dogs
and foxes will not hold good in reference to dogs, wolves, and
jackals. The wolf and the jackal are so much alike that the only
appreciable distinction is that of size, and so closely do they
resemble many dogs in general appearance, structure, habits,
instincts, and mental endowments that no difficulty presents itself
in regarding them as being of one stock. Wolves and jackals can be,
and have repeatedly been, tamed. Domestic dogs can become, and again
and again do become, wild, even consorting with wolves, interbreeding
with them, assuming their gregarious habits, and changing the
characteristic bark into a dismal wolf-like howl. The wolf and the
jackal when tamed answer to their master's call, wag their tails,
lick his hands, crouch, jump round him to be caressed, and throw
themselves on their backs in submission. When in high spirits they
run round in circles or in a figure of eight, with their tails between
their legs. Their howl becomes a business-like bark. They smell at
the tails of other dogs and void their urine sideways, and lastly,
like our domestic favourites, however refined and gentlemanly in other
respects, they cannot be broken of the habit of rolling on carrion
or on animals they have killed.