THE CO-OPERATION OF THE FACTORS. 553 



fast as the number of organs which co-operate in any given 

 function increases, indirect equilibration through natural 

 selection becomes less and less capable of producing specific 

 adaptations; and remains capable only of maintaining the 

 general fitness of constitution to conditions. The production 

 of adaptations by direct equilibration then takes the first 

 place: indirect equilibration serving to facilitate it. Until 

 at length, among the civilized human races, the equilibration 

 becomes mainly direct: the action of natural selection being 

 limited to the destruction of those who are constitutionally 

 too feeble to live, even with external aid. As the preserva- 

 tion of incapables is secured by our social arrangements; 

 and as very few save incarcerated criminals are prevented by 

 their inferiorities from leaving the average number of off- 

 spring; it results that survival of the fittest can scarcely at 

 all act in such way as to produce specialities of nature, either 

 bodily or mental. Here the specialities of nature, chiefly 

 mental, which we see produced, and which are so rapidly 

 produced that a few centuries show a considerable change, 

 must be ascribed almost wholly to direct equilibration.* 



* As bearing on the question of the varieties of Man, let me here refer 

 to a paper on " The Origin of the Human Races " read before the Anthro- 

 pological Society, March 1st, 1864, by Mr. Alfred Wallace. In this paper, 

 Mr. Wallace shows that along with the attainment of that intelligence 

 implied by the use of implements, clothing, &c., there arises a tendency for 

 modifications of brain to take the place of modifications of body : still, how. 

 ever, regarding the natural selection of spontaneous variations as the cause 

 of the modifications. But if the foregoing arguments be valid, natural 

 selection here plays but the secondary part of furthering the adaptations 

 otherwise caused. It is true that, as Mr. Wallace argues, and as I have 

 myself briefly indicated (see Weslminsfer Review, for April, 1852, pp. 496 — 

 601), the natural selection of races leads to the survival of the more 

 cerebrally-developed, while the less ccrebrally-developed disappear. But 

 though natural selection acts freely in the struggle of one society with 

 another; yet, among the units of each society, its action is so interfered 

 with that there remains no adequate cause for the acquirement of mental 

 superiority by one race over another, except the inheritance of functionally- 

 produced modifications. 



