166 A NEW THEORY OF EVOLUTION. 



simplest forms, Darwinism professes to ex- 

 plain the process of evolution and the pre- 

 ceding facts by the theory 



That new species were evolved from 

 their predecessors by secondary causes, 

 of which natural selection was the 

 principal ; 



That natural selection the outcome of 

 the struggle for existence selected for 

 survival animals that had, as compared 

 with their fellows, some beneficial dif- 

 ference ; 



That beneficial differences did appear, and 

 when accumulated by heredity became 

 specific variations, and gave rise to 

 new species ; and 



That this process was aided by the use, 

 disuse, or adaptation of organs, and by 

 changes in the conditions of existence. 



Darwin's principal arguments in support 

 of these conclusions are based on 



The similarity in structure and organisa- 

 tion between successive types in the 

 same line of evolution. 



The differences among domestic animals 

 of the same race. 



The (alleged) beneficial differences that 

 arise in greater or less degree among 

 all animals. 



