CROSSING AND CROSSED BREEDS. 257 



understood after alluding to the practice of " in-and-in " breeding, 

 but the second may now be considered with advantage. 



Among dogs, as among horses, certain varieties are remarkable 

 for particular qualities, and as the latter are more numerous in 

 the species Canis familiaris than in the horse, so there is a greater 

 opportunity for alteration. Thus in the horse there are speed, 

 stoutness, courage, temper, and shape (which includes action) to 

 be considered ; but in the dog there are also, over and above these, 

 nose and sagacity, the presence or absence of which in some 

 breeds is of the greatest importance. Now it happens that there 

 are certain old strains which have some of these qualities deve- 

 loped in a very high degree, but are deficient in others, and there- 

 fore they are only adapted to those breeds in which the qualities 

 they are deficient in are in excess. It is by a knowledge of 

 these properties, and by taking advantage of them, that our 

 modern breeds have been brought to the perfection at which they 

 have arrived ; carefully combining the plan with the principle of 

 selection, which is the great secret in all kinds of breeding. In 

 this way the foxhound has been produced by introducing the speed 

 of the greyhound, and in like manner the courage of the bull- 

 dog has been added to the speed of the greyhound, to establish 

 the present high form of that animal. So also the terrier, though 

 ardent enough in pursuit of vermin, is too great a coward to bear 

 their bites without flinching unless he is crossed with the bull- 

 dog ; and hence the bull-terrier is the most useful dog for that 

 purpose. Although many breeds of terrier so crossed are not 

 admitted to contain the bull strain, still it is notorious that a 

 vast proportion, if not all, have been crossed in this way some 

 generations back, and I firmly believe that without this blood in 

 their veins they are utterly useless. 



It might naturally be supposed by any person who has not 



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