The foregoing chapters have given abundant examples of how the various breeds of the dog have been acquired, manufactured, improved, resuscitated, and retained.  Broadly speaking, two methods have been adopted:  The method of introducing an outcross to impart new blood, new strength, new character; and the method of inbreeding to retain an approved type.  An outcross is introduced when the breed operated upon is declining in stamina or is in danger of extinction, or when some new physical or mental quality is desired.  New types and eccentricities are hardly wanted, however, and the extreme requirements of an outcross may nowadays be achieved by the simple process of selecting individuals from differing strains of the same breed, mating a bitch which lacks the required points with a dog in whose family they are prominently and consistently present.

Inbreeding is the reverse of outcrossing.  It is the practice of mating animals closely related to each other, and it is, within limits, an entirely justifiable means of preserving and intensifying family characteristics.  It is a law in zoology that an animal cannot transmit a quality which it does not itself innately possess, or which none of its progenitors has ever possessed.  By mating a dog and a bitch of the same family, therefore, you concentrate and enhance the uniform inheritable qualities into one line instead of two, and you reduce the number of possibly heterogeneous ancestors by exactly a half right back to the very beginning.  There is no surer way of maintaining uniformity of type, and an examination of the extended pedigree of almost any famous dog will show how commonly inbreeding is practised.  Inbreeding is certainly advantageous when managed with judgment and discreet selection, but it has its disadvantages also, for it is to be remembered that faults and blemishes are inherited as well as merits, and that the faults have a way of asserting themselves with annoying persistency.  Furthermore, breeding between animals closely allied in parentage is prone to lead to degeneracy, physical weakness, and mental stupidity, while impotence and sterility are frequent concomitants, and none but experienced breeders should attempt so hazardous an experiment.  Observation has proved that the union of father with daughter and mother with son is preferable to an alliance between brother and sister.  Perhaps the best union is that between cousins.  For the preservation of general type, however, it ought to be sufficient to keep to one strain and to select from that strain members who, while exhibiting similar characteristics, are not actually too closely allied in consanguinity.  To move perpetually from one strain to another is only to court an undesirable confusion of type.

In founding a kennel it is advisable to begin with the possession of a bitch.  As a companion the female is to be preferred to the male; she is not less affectionate and faithful, and she is usually much cleaner in her habits in the house.  If it is intended to breed by her, she should be very carefully chosen and proved to be free from any serious fault or predisposition to disease.  Not only should her written pedigree be scrupulously scrutinised, but her own constitution and that of her parents on both sides should be minutely inquired into.