P reformism and Accommodation 47 



ent correlations, or with differences in other characters 

 which make their behaviour in effecting accommodations 

 to the environment somewhat different. They adopt dif- 

 ferent ways of using their plastic substance and both live, 

 yet with considerable differences of habit and behaviour. 

 These, if there be enough individuals of each sort, would 

 carry on from generation to generation their respective 

 habits of life ; tradition would spring up to set and confirm 

 each group in its own way of life. And again there would 

 be divergent or polytypic evolution as the result, although 

 their original plasticity was the same. Here it is a ques- 

 tion of the correlations of the plasticity, not merely the 

 possession of it. In this case and the one just cited the 

 actual development dominates evolution, not merely the pos- 

 sible development. 1 I am not able, therefore, to see great 

 force in the contention of the preformists when they claim 

 that the recognition of the variation by which a function 

 is made possible in development supplies a sufficient theory 

 of the course of the development, and also of its results in 

 determining evolution. 



All this is notably true in the matter of mind, and in 

 evolution into which a strain of conscious accommodation 

 has entered. Let us say, for instance, that the female bird 

 has a certain capacity for preferential choice among possi- 

 ble males. This means nothing, unless she actually makes 

 a choice. Then the physical characters of the offspring 

 vary according as this male or that is chosen, and these 

 go down to posterity. It is the result which is the evolu- 

 tion, and it is conditioned upon the use made of the endow- 



1 As Professor Poulton says, speaking of organic selection in general (see 

 Appendix A), ' in this way natural selection would be compelled to act along a 

 certain path ' a strong and true statement. 



