A FINAL WAKNIKG. 405 



universal difficulty of deciding whether a certain modification 

 which has taken place is to be ascribed to some direct determin- 

 ing and transforming cause, or to the enhancing of a previously- 

 modified character, which is frequently connected with selection, 

 that it becomes imperative that we should in the first place 

 carry out the most exact research possible by means of experi- 

 ment, and also wean ourselves of the convenient — but, as it 

 seems to me, highly pernicious — habit of theoretical explana- 

 tions from general propositions. Otherwise there is great danger 

 that the bright expectation which Darwin has opened out to us 

 by his theory may be baffled — the prospect of gradually bring- 

 ing even Organic Being within reach of that method of inquiry 

 which seeks to discern mechanical efficient causes. 



