430 THE CAUSES OF THE 



XI 



can prove and this comes to the same thing 

 that varieties exist in nature within the limits of 

 species, and, what is more, that when a variety has 

 come into existence in nature, there are natural 

 causes and conditions, which are amply competent 

 to play the part of a selective breeder ; and al- 

 though that is not quite the evidence that one 

 would like to have though it is not direct testi- 

 mony yet it is exceeding good and exceedingly 

 powerful evidence in its way. 



As to the first point, of varieties existing 

 among natural species, I might appeal to the 

 universal experience of every naturalist, and of 

 any person who has ever turned any attention 

 at all to the characteristics of plants and animals 

 in a state of nature; but I may as well take 

 a few definite cases, and I will begin with Man 

 himself. 



I am one of those who believe that, at present, 

 there is no evidence whatever for saying, that man- 

 kind sprang originally from any more than a single 

 pair; I must say, that I cannot see any good 

 ground whatever, or even any tenable sort of evi- 

 dence, for believing that there is more than one 

 species of Man. Nevertheless, as you know, just 

 as there are numbers of varieties in animals, so 

 there are remarkable varieties of men. I speak 

 not merely of those broad and distinct variations 

 which you see at a glance. Everybody, of course, 

 knows the difference between a Negro and a white 



