FACTORS OF ORGANIC EVOLUTION 45 



fertile than those between individuals markedly 

 unlike, the principle might be regarded as applicable 

 to plants as well as to animals; but Professor 

 Pearson tells me that, as yet, there have been made 

 practically no investigations into this aspect of the 

 question. 



CHAPTER VII 



THE FACTORS OF ORGANIC EVOLUTION— 

 TRANSMISSION OF ACQUIREMENTS 



Concerning the action of natural selection and 

 sexual selection no one now doubts, but concerning 

 the action of the factor now to be discussed there 

 still rages much controversy, and the more accepted 

 opinion is that this factor is entirely inoperative. 



It is plain that if acquired characters or acquire- 

 ments are transmitted, such transmission must be a 

 factor in organic evolution — and a most potent one. 

 But the question first to be answered is, Are they 

 transmitted ? Until not so long ago every one 

 would have answered this question in the affir- 

 mative. Lamarck, who founded the belief in this 

 factor, would have been seconded by Darwin him- 

 self, who even invented a theory to explain the 

 manner of its occurrence. Spencer also would have 

 rendered an affirmative, and so does Haeckel to- 

 day. 



The question here at issue is plainly a problem 

 of heredity, and I have discussed it at no greater 

 length than its importance demands in a companion 

 volume to this. Here, therefore, the matter may 



