338 Darwin, and after Darwin. 



Take any analogous case. The selective agency 

 of specific gravity which is utilised in gold-washing 

 does not create the original differences between gold- 

 dust and dust of all other kinds. But these differ- 

 ences being presented by as many different bodies 

 in nature, the gold-washer takes advantage of the 

 selective agency in question, and, by using it as a 

 cause of segregation, is enabled to separate the gold 

 from all the earths with which it may happen to be 

 mixed. So far as the objects of the gold-washer are 

 concerned, it is immaterial with what other earths 

 the gold-dust may happen to be mixed. For 

 although gold-dust may occur in intimate association 

 with earths of various kinds in various proportions, 

 and although in each case the particular admixture 

 which occurs must have been due to definite causes, 

 these things, in relation to the selective process of 

 the washer, are what is called accidental : that is 

 to say, they have nothing to do with the causative 

 action of the selective process. Now, in precisely 

 the same sense Darwin calls the multitudinous varia- 

 tions of plants and animals accidental. By so calling 

 them he expressly says he does not suppose them 

 to be accidental in the sense of not all being due 

 to definite causes. But they are accidental in rela- 

 tion to the sifting process of natural selection : all 

 that they have to do is to furnish the promiscuous 

 material on which this sifting process acts. 



Or let us take an even closer analogy. The power 

 of selective breeding by man is so wonderful, that in 

 the course of successive generations all kinds of 

 peculiarities as to size, shape, colour, special appen- 

 dages or abortions, &c., can be produced at pleasure, 



