Page:George Archdall Reid 1896 The present evolution of man.djvu/101

Rh 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 which it 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 discriminativeness 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