DARWIN 9 



and therefore Mr. Darwin's book, if there is any truth in it at 

 all, has a logical claim to its title. It shows how ' species/ or 

 stable forms, are produced out of unstable spontaneous varia- 

 tions, which is certainly to trace their ' origin/ The distinc- 

 tion of ' species ' and ' individual ' is equally important. A 

 horse, or a number of horses, as such, do not constitute a 

 * species/ It is the comparative permanence of the form as 

 distinguished from the ass, quagga, zebra, tapir, camel, etc., 

 that makes them one. Were there a mass of intermediate 

 forms connecting all these animals by fine gradations and 

 hardly a dozen individuals alike — as would probably be the 

 case had selection not acted — there might be a few horses, 

 but there would be no such thing as a species of horse. That 

 could only be produced by some power capable of eliminating 

 intermediate forms as they arose, and preserving all of the 

 true horse type; and such a power was first shown to exist 

 by Mr. Darwin. The origin of varieties and individuals is 

 one thing, the origin of species another." 



It is a remarkable thing that this very simple preliminary 

 misunderstanding of the very meaning of the term " species ' 

 continued to appear year after year in most of the criticisms 

 of the theory of natural selection. It was put forward both 

 by mere literary critics and also by naturalists, and was in 

 many cases adduced as a discovery which completely over- 

 threw the whole of Darwin's work. So frequent was it that 

 twenty years later, when writing my " Darwinism/' I found it 

 necessary to devote the first chapter to a thorough explanation 

 of this point, under the heading, " What are ' Species/ and 

 what is meant by their * Origin ' ? " and I think I may feel 

 confident that to those who have read that work this particular 

 purely imaginary difficulty will no longer exist. 



Soon after the " Descent of Man " appeared, I wrote to 

 Darwin, giving my impressions of the first volume, to which 

 he replied (January 30, 1871). This letter is given in the 

 "Life and Letters" (iii. p. 134), but I will quote two short 

 passages expressing his kind feelings towards myself. He 

 begins, " Your note has given me very great pleasure, chiefly 

 because I was so anxious not to treat you with the least dis- 



