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CHAPTER XX 



ARTIFICIAL SELECTION 



The evolution of the domesticated races of Pigeons, Fowls, etc. Reversion 

 of domesticated races to the wild, ancestral type. Physiological and morphological 

 species. Fertility and the test of species. 



THOSE who have but a slight acquaintance with zoology, 

 that is to say, those whose knowledge of wild animals 

 is, by force of circumstances, limited, must always 

 find it difficult to grasp the real meaning and full significance 

 of the evolution theory. If, however, those thus handicapped 

 would turn to the study of the various races of domesticated 

 animals much that was obscure would soon become clear. In 

 the present chapter it is proposed to deal shortly with the main 

 results of Darwin's work in this field, in so far as birds are con- 

 cerned. 



As the outcome of his years of patient labour it has now 

 become a matter of common knowledge that the various types 

 of Pigeons, Fowls and Ducks, for example, have been created 

 by the exercise of the breeder's art — by the selection for breeding 

 purposes of individuals which presented any particular feature 

 which he desired to preserve and develop. Starting, in each 

 case, with a wild species, varieties or races thereof have been 

 raised up which now differ more from the original parent stock 

 than wild species and genera differ one from another, in so far 

 as external characters are concerned. 



The domesticated races of the Pigeon, for instance, have all 

 been derived from the Rock-dove {Columba livid) still found 

 wild in many parts of Great Britain and the mountainous parts 

 of Europe, and ranging eastwards into India. 



From this stock no less than 200 distinct races have been 

 built up. Naturally there is a great deal of intergradation to be 

 found in a survey of this number as a whole, but from among 



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