ORGANIC EVOLUTION — THE FACTORS 89 



cannot be due to the action of Natural Selection (i. e. to 

 the accumulation of inborn traits), for, to take an example, 

 the fact that the tip of the nose has more than three 

 times the power of discrimination possessed by the lower 

 part of the forehead is not of such moment to the 

 individual as to be important as a factor in survival, 

 whereas it is manifest that the tactual sensibility of each 

 part is proportionate to the amount of tactual use to 

 whichjt is put. He argues, therefore, that the differences 

 of tactual sensibility between different parts of the 

 surface of the body are acquired, not inborn variations. 

 All this may be admitted, but it appears to me that it 

 does not touch the matter in dispute. The question is 

 not as to whether variations can be acquired, but 

 whether they can be transmitted. Mr. Spencer himself, 

 by his experiments on the fingers of compositors, proves 

 that greatly increased tactual discriminativeness may 

 be acquired by individuals, but he does not prove, nor 

 does he attempt to prove, that the increase, in however 

 small a degree, is inherited by the offspring. It may, 

 however, be argued, and I think it is implied in Mr. 

 Spencer's paper, that if it be admitted, as I think it 

 must, that the differences in the tactual discriminative- 

 ness of the various parts of the body are not altogether 

 or even mainly due to the accumulation of inborn 

 variations, but are in part or even mainly the outcome 

 of acquired variations, then these differences are so great 

 that they cannot have arisen as acquired variations in a 

 single individual, but must have resulted from the 

 accumulation of the acquired and transmitted variations 

 of a line of individuals. Let us examine the question 

 more closely. 



It is known to all that the structures of individual 

 organisms, especially the higher multicellular animal 

 organisms, possess the power of adapting themselves to 

 changes in the environment by varying to quite a 



