32 THE OLD ENGLISH SHEEP DOG 



principles which are to be taken into account in the 

 selection of a suitable mate namely, heredity, atavism, 

 natural variability, and prepotency. To study carefully 

 the working of these laws, and to take advantage of them 

 for the purpose of reproducing a desired type is the 

 breeder's alphabet. Obviously there are many instances 

 in which they will appear to be antagonistic to one 

 another. 



For instance, a stud dog whose fault is an unduly long 

 back may have proved himself a consistent breeder of 

 short-backed stock, though mated with bitches of various 

 sizes. On his own appearance you would unhesitatingly 

 discard his services. But a study of his ancestry proves 

 conclusively that he comes of a short-backed strain. You 

 deduce then that the explanation of his own failing is 

 an accident of atavism or of natural variability, but that 

 he is prepotent to reproduce the short back characteristic 

 of his ancestors. His litter brother may be a champion, 

 whilst he himself has never won a prize. But he may be 

 an invaluable animal to breed from for all that. 



This is the point at which the breeder's personal judg- 

 ment and logical powers of deduction come into play. 

 Some men have a natural aptitude for wise selection, and 

 seem to know instinctively what to reject ; some only 

 acquire the art as the result of repeated failures, and many 

 never learn it in a lifetime. But the root principle of the 

 matter is so sound, and so well established, that any 

 observant person of ordinary intelligence may grasp the 



