THEORIES OF BREEDING 



In considering the methods of breeding, we must first 

 clearly understand that we are dealing with forms produced 

 by artificial means. The standards which are the accepted 

 criteria in the majority of cases are based on the whims of 

 individual persons or small groups. They frequently are 

 formed without strict regard to beauty or utility and are 

 subject to constant change, not invariably for the better. 

 Vacillating conceptions of the ideal and lack of full under- 

 standing of the laws which govern careful breeding are 

 evils from which stock rearing never will be entirely 

 free. 



In the cultivation of our domesticated animals, we influ- 

 ence them as wild species are influenced by nature, the in- 

 telligent control of man replacing the effects of the forces 

 which govern the development of feral forms. Since do- 

 mestic breeds are artificially produced and controlled, it 

 is evident that it is essential to adhere rigidly to the con- 

 ditions which brought them into being. Variation in en- 

 vironment is very likely to cause changes even in well- 

 established natural species; any neglect of the rules of the 

 artificial evolution which produced man-made breeds will 

 result in quick deterioration. Selection, ontogeny, heredity 

 and environment, the four factors which, according to 

 Professor Osborn,* are most potent in governing natural 

 evolution, are equally influential in the maintenance of 

 domestic varieties. They are the tools with which the 



* Osborn, Henry Fairfield : " Tetraplasy, the Law of the Four In- 

 separable Factors of Evolution," Journ. Ac. Set. Phil., Vol. XV, 2nd 

 Series, 1912, pp. 278-309. 



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