608 APPENDIX B. 



it useful, it could not be shown that it has been developed by 

 survival of the fittest ; for though perfect articulation is an aid, 

 yet imperfect articulation has rarely such an effect as to impede 

 a man in the maintenance of his life. If he is a good workman, 

 a German's interchanges of Us and p*s do not disadvantage him. 

 A Frenchman who, in place of the sound of th, always makes the 

 sound of z, succeeds as a teacher of music or dancing, no less 

 than if he achieved the English pronunciation. Nay, even such 

 an imperfection of speech as that which arises from cleft palate, 

 does not prevent a man from getting on if he is capable. True, 

 it may go against him as a candidate for Parliament, or as an 

 " orator " of the unemployed (mostly not worth employing). But 

 in the struggle for life he is not hindered by the effect to the 

 extent of being less able than others to maintain himself and 

 his offspring. Clearly, then, even if this unparalleled perceptive- 

 ness of the tongue-tip is required for perfect speech, such use iy 

 not sufficiently important to have been developed by natural 

 selection. 



How, then, is this remarkable trait of the tongue-tip to be 

 accounted for ? Without difficulty, if there is inheritance cf 

 acquired characters. For the tongue-tip has, above all other 

 parts of the body, unceasing experiences of small irregularities of 

 surface. It is in contact with the teeth, and either consciously or 

 unconsciously is continually exploring them. There is hardly a 

 moment in which impressions of adjacent but different positions 

 are not being yielded to it by either the surfaces of the teeth or 

 their edges ; and it is continually being moved about from some 

 of them to others. No advantage is gained. It is simply that 

 the tongue's position renders perpetual exploration almost inevit- 

 able ; and by perpetual exploration is developed this unique power 

 of discrimination. Thus the law holds throughout, from this 

 highest degree of perceptiveness of the tongue-tip to its lowest 

 degree on the back of the trunk ; and no other explanation of 

 the facts seems possible. 



" Yes, there is another explanation," I hear some one say : 

 " they may be explained by panmixia." Well, in the first place, 

 as the explanation by panmixia implies that these gradations of 

 perceptiveness have been arrived at by the dwindling of nervous 

 structures, there lies at the basis of the explanation an unproved 

 and improbable assumption ; and, in the second place, even were 

 there no such difficulty, it may with certainty be denied that 

 panmixia can furnish an explanation. Let us look at its preten- 

 sions. 



It was not without good reason that Bentham protested 

 against metaphors. Figures of speech in general, valuable as they 



