DARWINISM ATTACKED. 27 



Among the critics of the selection theories we must note 



two groups, differing in the character of their criticism 



, , more in degree than in kind, perhaps, but still 



iwo groups oi 

 scientific at- importantly differing. One group denies in 



toto any effectiveness or capacity for species- 

 forming on the part of natural selection, while the other 

 group, a larger one, sees in natural selection an effective 

 factor in directing or controlling the general course of 

 descent, holding it to adaptive lines, but denies it outright 

 any such Allmacht of species control as the more eager 

 selectionists, the so-called neo-Darwinians or Weismann- 

 ians, credit it with. This larger group of critics sees in 

 natural selection an evolutionary factor capable of initiating 

 nothing, dependent wholly for any effectiveness on some 

 primary factor or factors controlling the origin and direc- 

 tion of variation, but wholly capable of extinguishing all 

 unadapted, unfit lines of development, and, in this way, of 

 exercising decisive final control over the general course of 

 descent, i. e., organic evolution. Another classification of 

 critics may be made on the basis of pure destructiveness on 

 the one hand as opposed to destructiveness combined with 

 constructiveness on the other. That is, some critics of selec- 

 tion, as Wolff, Pfeffer, Driesch, et a/., are content with doing 

 their best to reveal the incapacity of Darwinism ; others, 

 on the contrary, come with certain more or less well-outlined 

 substitutionary theories in their hands. Eimer with his 

 theory of orthogenesis, and Korschinsky and de Vries with 

 their theory of mutations, are examples of the latter class. 

 The general impression left on one after a considerable 

 course of anti-Darwinian reading ranging all the way from 



the extreme attitude and the violence of Den- 

 attwk n ?nd weak- nert > Fleischmann, Wolff, and Coe, to the 

 ness in substitn- tempered and reserved criticism of Delage and 



de Vries, is that there is a very real and effective 

 amount of destructive criticism for Darwinians to meet ; and 



