ORIGINATIVE FACTORS IN EVOIUTION 513 



and eugenics, may afford a useful touchstone for testing the 

 vaHdity of the more complex sociological ideals. 



(3) The parallelism of the two sciences is such that biological 

 conclusions and experiences may have great suggestive value 

 to sociology, aiding in the discovery of sociological laws and 

 indicating practicable possibilities of social evolution. 



To illustrate this threefold value of the appeal to biology, 

 and at the same time the risk that biology, used unduly as a 

 support, may pierce the sociological hand, we propose in this 

 chapter to consider a few biological generalisations and to 

 inquire into their bearing on sociological problems. 



§ 3. Originative Factors in Evolution 



Variations. — Our biological knowledge of the nature and 

 origin of those changes or variations which form the raw material 

 of organic progress is still incipient ; yet the little we know 

 must be borne in mind in sociological discussions. There is 

 general agreement that inborn variations — which give every 

 organism its individuality — are the expression of changes in 

 the intricate architecture of the germ-plasm. It is suggested 

 that they are due {a) to the influences of the environing " body," 

 with its variable nutritive stream, on the germ-cells ; (b) to 

 the intricate permutations and combinations preparatory to 

 and implied in fertilisation ; and (c) perhaps to what may be 

 called growth-changes in the germ-plasm as it is continued 

 from generation to generation. We are sure that these en- 

 dogenous or germinal changes, expressing themselves in develop- 

 ment, supply the raw material of evolution on which selection 

 operates, and we are not sure that there is any other source of 

 raw material. 



Compared with most organisms, man is a slowly reproducing, 

 slightly varying, creature. In so far as deeply ingrained char- 

 acters are concerned, a bodily change in the race by natural 



