must have been practised, in order to
improve them in a definite manner. As soon as any strain or family became
slightly improved or better adapted to altered circumstances, it would tend
to supplant the older and less improved strains. For instance, as soon as
the old foxhound was improved by a cross with the greyhound, or by simple
selection, and assumed its present character--and the change was probably
required by {43} the increased fleetness of our hunters--it rapidly spread
throughout the country, and is now everywhere nearly uniform. But the
process of improvement is still going on, for every one tries to improve
his strain by occasionally procuring dogs from the best kennels. Through
this process of gradual substitution the old English hound has been lost;
and so it has been with the old Irish greyhound and apparently with the old
English bulldog. But the extinction of former breeds is apparently aided by
another cause; for whenever a breed is kept in scanty numbers, as at
present with the bloodhound, it is reared with difficulty, and this
apparently is due to the evil effects of long-continued close
interbreeding. As several breeds of the dog have been slightly but sensibly
modified within so short a period as the last one or two centuries, by the
selection of the best individual dogs, modified in many cases by crosses
with other breeds; and as we shall hereafter see that the breeding of dogs
was attended to in ancient times, as it still is by savages, we may
conclude that we have in selection, even if only occasionally practised, a
potent means of modification.

DOMESTIC CATS.

Cats have been domesticated in the East from an ancient period; Mr. Blyth
informs me that they are mentioned in a Sanskrit writing 2000 years old,
and in Egypt their antiquity is known to be even greater, as shown by
monumental drawings and their mummied bodies. These mummies, according to
De Blainville[88] who has particularly studied the subject, belong to no
less than three species, namely, _F. caligulata_, _bubastes_, and _chaus_.
The two former species are said to be still found, both wild and
domesticated, in parts of Egypt. _F. caligulata_ presents a difference in
the first inferior milk molar tooth, as compared with the domestic cats of
Europe, which makes De Blainville conclude that it is not one of the
parent-forms of our cats. Several naturalists, as Pallas, Temminck, Blyth,
believe that domestic cats are the descendants of s