338 NATURAL SCIENCE. May, 



Tactile sensibility scarcely exists in the internal organs, where it 

 wonld be worse than useless. It is most delicate in the tip of the 

 tongue, which keenly examines food by touch as well as by taste, and 

 in the tips of the fingers, which serve as tactile and manipulative 

 organs. The face, though including highly important organs, does 

 not need so discriminative a perceptiveness as the tongue and finger, 

 and accordingly possesses much less even in the lips and the tip of 

 the nose, where its tactile sensibility is finest. The body and limbs, 

 which have never needed a highly discriminative sense of touch, have- 

 never evolved such keen sensibility, so far as is known, and the Neo- 

 Darwinian has, therefore, no need to adopt the suggestion of degene- 

 racy under panmixia so superfluously made on his behalf. The back 

 of the head and body has less perceptive power than the front, where 

 it has been more needed, since we move in a forward direction, and 

 meet or touch objects in front of us more often than objects in the 

 rear. Great part of our tactile equipment dates back to very remote 

 eras. Tongue, fingers, toes, lips, and nose must have evolved special 

 tactile powers even before our ancestors had arrived at the Simian 

 stage of evolution ; and in passing through foliage, branches, and 

 thorny bushes a fairly developed sense of touch in the face would be 

 far more serviceable than in the back of the head, and the chest and 

 limbs might well become somewhat more discriminative than the 

 back. 



While the relative sensibility of parts can in the main be 

 accounted for by the Neo-Darwinian, it must be freely admitted that 

 we cannot fully and decisively explain every detail, every minor modi- 

 fication, and every gradation, by the principle of the survival of the 

 fittest. We may be unable, for instance, to explain why the thigh and 

 fore-arm are less sensitive in the middle than near the end, or why 

 the skin over the malar bone is less discriminative than other parts of 

 the cheek, or why the tip of the nose retains a measure of tactile 

 perceptiveness exceeding that of the palm of the hand ; but our 

 failure to unravel and clearly demonstrate every obscure cause 

 of the minor facts of variation and evolution proves nothing. Even 

 if we accept Mr. Spencer's view of the inadequacy of Neo-Darwinian 

 factors, we still have to inquire whether use-inheritance will fill the 

 gap, or whether it is equally or still more inadequate to afford the 

 desired explanation. Does it help us to account for the fact that the 

 tip of the nose is four-and-a-half times as discriminative as the back 

 of the hand ? - Is it reasonable to suppose that the nose comes into 

 contact with objects far more frequently than the back of the hand 

 does ? Does it touch things just about as often as the third or lowest 

 joints of the fingers, three times as often as the lower part of the 



2 The numbers in these comparisons might fairly be scjuared so as to represent 

 the relati\e number of separate tactile areas in a given space instead of linear dis- 

 tances. Thus estimated, the tip of the nose is twenty times as sensitive as the back, 

 of the hand. 



