196 VOL U TION A ND DOGMA . 



that he had at first over-estimated its importance. 

 Sexual selection, and the two Lamarckian factors 

 just referred to, he always considered as quite sec- 

 ondary and subordinate to natural selection. But 

 some of Darwin's disciples, notably Wallace, Haeckel, 

 and Ray Lankester, attribute a far greater potency 

 to natural selection than did Darwin himself, and are 

 disposed to regard it as the sole and sufficient cause 

 of all organic development. So different, indeed, 

 are their views from those of their master, that they 

 have given rise to a new school of thought known as 

 Neo-Darwinism. 



Evolutionary Theories and Their Difficulties. 



But all the theories of Evolution connected with 

 the above-named factors, Lamarckism and Darwin- 

 ism, Neo-Lamarckism and Neo-Darwinism, involve 

 numerous and grave difficulties, which, so far, have 

 not been satisfactorily answered. Thus, it is not 

 yet positively demonstrated that the effects of use 

 and disuse are inherited. To obtain direct evidence 

 of the inheritance of acquired variations of this kind 

 has hitherto been attended with insuperable diffi- 

 culties. As to natural selection, it labors under dif- 

 ficulties which are apparently even more serious, 

 and to such an extent is this true, that it may well 

 be questioned if there is a single pure Darwinian 

 now living. ' 



1 Many years ago, it will be remembered, Mivart charac- 

 terized natural selection as "a puerile hypothesis." Time seems 

 to have confirmed him in his opinion, for in a recent magazine 

 article he refers to natural selection as an "absurd and childish 

 theory." 



