92 NO STRUGGLE NO SELECTION 



way for preservation, when like is paired with like 

 through successive generations ; for destruction, when 

 there is the constant mingling of dissimilar individual 

 differences by the free intercrossing that is the rule 

 among Nature's tribes. 



There is no law more inevitable and more sure in 

 its action than this law of marriage. In the realm of 

 Nature it preserves the characteristics of species, and 

 acts to the speedy extinction of individual differences : 

 for thus has Nature willed that it should be. 



If a negro in this country be married to a white 

 woman, and their descendants constantly marry white 

 persons, the traces of the black blood will be found to 

 have completely disappeared in the seventh generation, 

 though it is distinctly traceable in the fifth. Galton's 

 investigations in respect of inherited genius confirm 

 this principle of extrusion of individual differences 

 after a few generations. Darwin's endeavour to deny 

 the destructive effect of the free intercourse which 

 takes place in Nature upon individual variations, and 

 his implicit assertion that there are variations which 

 resist its influence, and do not merely maintain them- 

 selves through constant intercrossing, but go on 

 accumulating from time to time as opportunity offers, 

 have caused me more surprise than anything I have 

 encountered in the course of a long life's reading. In 

 his treatment of it, and to subserve the requirements 

 of his theory, the individual variation becomes an 

 utterly lawless principle, a quite irresponsible entity, 

 building up species by means unknown to Nature, and 



