130 DOCTRINE OF EVOLUTION 



shorter period before they too succumb. Thus the 

 destruction of the unfit leaves the field to the better 

 adapted, that is, to those that vary in such a way as to 

 be completely or at least partially adapted to carry on 

 an efficient life. In this way Darwinism explains the 

 universal condition of organic adjustment, showing 

 that it exists because there is no place in nature for 

 the incompetent. 



Finally we come to * the process of inheritance as 

 viewed by Darwin, and its part in the production and 

 perfection of new species. In every case, Darwin said, 

 the efficiency or inefficiency of an animal depends upon 

 its characteristics of an inherited or congenital nature. 

 Variations in these qualities provide the array of more 

 or less different individuals from which impersonal 

 nature selects the better by throwing out first the 

 inferior ones. An organism can certainly change in 

 direct response to environmental influence or by the 

 indirect results of use and disuse, but not unless it is 

 so constituted by heredity as to be able to change adap- 

 tively. Therefore the final basis of success in life must 

 be sought in the inherited constitutions of organic forms. 



For the reason that the qualities which preserve an 

 animal's existence are already congenital, they are 

 already transmissible, as Darwin contended. Since 

 his time much has been learned about the course of 

 inheritance and its physical basis, and the new discov- 

 eries have confirmed the essential truth of Darwin's 

 statement that the congenital characters only possess 

 a real power in the evolution of species. 



