138 DOCTRINE OF EVOLUTION 



the history of the game cock, which has nearly doubled 

 in height since 1850, while at the same time its slender 

 legs, long spurs, and other qualities have been perfected 

 for the cruel sport for which it has been bred. Again, 

 the wild rock pigeon seems to be the ancestral form 

 from which the fantail and pouter and carrier-pigeon 

 with their diverse characters have taken their origin. 



It is true that some biologists have urged certain 

 technical objections to the employment of domesticated 

 animals and their history as analogies to the processes 

 and results in wild nature. To my mind, however, 

 artificial selection is truly a part of the whole process 

 of natural selection. Man is but one element of the 

 environment of tame forms, and his fancy or need is 

 therefore one of the varied series of external criteria 

 that must be met if survival is to be the result ; failing 

 this, ehmination follows as surely as under the conditions 

 of an area uninhabited or uninfluenced by mankind. 

 Congenital variation is real, selection is real, and the 

 heredity of the more fit modification is equally real. 

 Surely Darwin was right in contending that the facts 

 of this class amplify the conception of natural selection 

 developed on the basis of an analysis of wild life. 



Knowing the elements of the selective process, it is 

 possible to analyze and to understand many significant 

 phenomena of nature, and to gain a clearer conception of 

 the results of the struggle for existence, especially when 

 the human factor is involved. Let us see how much 

 is revealed when the foregoing results are employed in 

 a further study of some of nature's vital situations. 



