NATURAL SELECTION 85 



either there has been inheritance of acquired charac- 

 ters, or there has been no evolution." 



Also, " For the inheritance of acquired characters, 

 which it is now the fashion of the biological world to 

 deny, was by Mr. Darwin fully recognized and often 

 insisted on." . . . "The neo-Darwinists, how- 

 ever, do not admit this cause at all." 



In concluding he says: " See then how the cause 

 stands. Natural selection, or survival of the fittest, 

 is almost exclusively operative throughout the 

 vegetable world, and throughout the lower animal 

 world, characterized by relative passivity. But with 

 the ascent to higher types of animals, its effects are 

 in increasing degrees involved with those produced 

 by inheritance of acquired characters, until, in ani- 

 mals of complex structures, inheritance of acquired 

 characters becomes an important, if not the chief, 

 cause of evolution." 



He admits that known facts which show that ac- 

 quired characters are inherited are few, but he thinks 

 that they are "as large a number as can be expected, 

 considering the difficulty of observing them and the 

 absence of search." 



From the above, we see that the biological world is 

 against Mr. Spencer's view; that he would abandon 

 the theory of evolution unless acquired characters had 

 been inherited, but that facts in support of this 

 theory are meager. 



I think that his argument shows the insufficiency of 

 the theory of natural selection, but the truth of his 

 own theory remains to be established. We shall see 

 further on that natural selection has been supple- 

 mented by the theories of sexual selection and of the 

 correlation of growth 



If Mr. Spencer's theory as to the inheritance of 

 acquired characters is true, still I do not see how 



