THE BREEDING OF ANIMALS, IN GENERAL 77 



success in breeding by depending upon blood alone for improve- 

 ment of his stock. He has forgotten that all of our .improved 

 breeds are the product of adequate nutrition combined with 

 intelligent breeding, suitable environment, sufficient shelter, 

 and kindly care. 



Crossing. — The uniting of dissimilar animals is another 

 cause of variation. Up to the time of Bakewell, cross-breeding 

 was one of the chief means by 

 which improvement was sought. 

 This was before the time of 

 pedigree books, and crossing 

 was made easy from the fact 

 that no record of the breeding 

 was kept. It was also observed 

 that the uniting of two animals 

 that were unrelated, or that 

 had existed under different en- „ „^ „ ,. ,,„ 



. Fig. 36. — SuFroLK MARis Bawdset 



vironment, resulted m mcreased Pearl." Three years old. 



constitutional vigor and in many 



cases in greater prolificacy, and often individual improve- 

 ments. The great difficulty came when they attempted to 

 breed these cross-bred animals. The offspring of cross-bred 

 animals varied widely, some were good, more poor, and no 

 one could foretell which way the offspring would tend to de- 

 velop. While crossing is a cause of much variation, the results 

 are usually disappointing in the end. The fact must be recog- 

 nized, however, that the abundant crossing practiced by the 

 early British breeders gave to the animals a plasticity of con- 

 formation that prepared them for quick improvement when 

 subjected to the Bakewell method. 



SELECTION 



The purpose of selection is to modify the type to suit our 

 purpose, to prevent as far as possible the production of unde- 



