A COUNTER CRITICISM. 157 



schoolmaster by his knowledge, the farm-hailiff by his diligence 

 and care, succeed in the struggle for existence equally well. The 

 advantage of a strong arm does not predominate over the ad- 

 vantages which other men gain by their innate or acquired pow- 

 ers of other kinds ; and therefore natural selection cannot oper- 

 ate so as to increase the trait. Before it can be increased, it is 

 neutralised by the unions of those having it with those having 

 other traits. To whatever extent, therefore, inheritance of this 

 functionally-produced modification operates, it operates inde- 

 pendently of natural selection. 



One other point has to be noted — the relative importance of 

 this factor. If additional developments of muscle may be trans- 

 mitted ; if, as Mr. Darwin held, there are various structural 

 modifications caused by use and disuse which imply inheri- 

 tance of this kind ; if acquired characters are hereditary, as the 

 Duke of Argyll believes ; — then the area over which this factor 

 of organic evolution operates is enormous. Not every muscle 

 only, but every nerve and nerve-centre, every blood-vessel, every 

 viscus, and nearly every bone, may be increased or decreased by 

 its influence. Excepting parts which have passive functions, 

 such as dermal appendages and the bones which form the skull, 

 the implication is that nearly every organ in the body may be 

 modified in successive generations by the augmented or dimin- 

 ished activity required of it ; and, save in the few cases where 

 the change caused is one which conduces to survival in a pre- 

 eminent degree, will be thus modified independently of natural 

 selection. Though this factor can operate but little in the vege- 

 tal world, and can play but a subordinate part in the lowest ani- 

 mal world ; yet, seeing that all the active organs of all animals 

 are subject to its influence, it has an immense sphere. The 

 Duke of Argyll compares the claim made for this factor to 

 " some bit of Bumbledom setting up for Home Rule — some paro- 

 chial vestry claiming independence of a universal empire." But, 

 far from this, the claim made for it is to an empire, less indeed 

 than that of natural selection, and over a small part of which 

 natural selection exercises concurrent power, but of which the 

 independent part has an area that is immense. 



It seems to me, then, that the Duke of Argyll is mistaken in 

 four of the propositions contained in the passages I have quoted. 

 The inheritance of acquired characters is disputed by biologists, 

 though he thinks it is not. It is not true that " heredity is the 

 central idea of natural selection." The statement that natural 

 selection includes and covers all the causes which can possibly 

 operate through inheritance, is quite erroneous. And if the in- 

 heritance of acquired characters is a factor at all, the dominion 

 it rules over is not insignificant but vast. 



