DIVISION OF LABOUR. 27 1 



great number of weeds can exist, and, moreover, in places 

 which could not have been occupied by corn-plants. The 

 more dry and sterile places of the ground, in which no corn- 

 plant would thrive, may still furnish sustenance to weeds of 

 different kinds ; and such species and individuals of weeds 

 will more readily be able to exist in such conditions, in pro- 

 portion as they are suited to adapt themselves to the dif- 

 ferent parts of the ground. It is the same with animals. It 

 is evident that a much greater number of animal indivi- 

 duals can live together in one and the same limited district, if 

 they are of various and different natures, than if they 

 are all alike. There are trees (for example, the oak) on 

 which a couple of hundred of different species of insects live 

 together. Some feed on the fruits of the tree, others on the 

 leaves, others again on the bark, the root, etc. It would be 

 quite impossible for an equal number of individuals to live 

 on this tree if all were of one species ; if, for example, all fed 

 on the bark, or only upon the leaves. Exactly the same is 

 the case in human society. In one and the same small town, 

 only a certain number of workmen can exist, even when 

 they follow different occupations. The division of labour, 

 which is of the greatest use to the whole community, as well 

 as to the individual workman, is a direct consequence of the 

 struggle for life, of natural selection ; for this struggle can 

 be sustained more easily the more the activities, and hence, 

 also, the forms of the different individuals deviate from 

 one another. The different function naturally produces its 

 reaction in changing the form, and the physiological divi- 

 sion of labour necessarily determines the morphological 

 differentiation, that is, the " divergence of character." ^^ 

 Now, I beg the reader again to remember that all species 



