Introduction. 5 



favourable variations ; aided in an important manner by the 

 inherited effects of the use and disuse of parts ; and in an un- 

 important manner, that is in relation to adaptive structures, 

 whether past or present, by the direct action of external con- 

 ditions, and by variations which seem to us in our ignorance to 

 arise spontaneously. It appears that I formerly underrated the 

 frequency and value of these latter forms of variation, as leading 

 to permanent modifications of structure independently of natural 

 selection. But as my conclusions have lately been much mis- 

 represented, and it has been stated that I attribute the modifica- 

 tion of species exclusively to natural selection, I may be permitted 

 to remark that in the first edition of this work, and subsequently, 

 I placed in a most conspicuous position namely, at the close 

 of the Introduction the following words : ' I am convinced that 

 natural selection has been the main, but not the exclusive means 

 of modification.' This has been of no avail. Great is the 

 power of steady misrepresentation ; but the history of science 

 shows that fortunately this power does not long endure." 



In the whole range of Darwin's writings there 

 cannot be found a passage so strongly worded as 

 this : it presents the only note of bitterness in all 

 the thousands of pages which he has published. 

 Therefore I do not think it is necessary to supply 

 any further quotations for the purpose of proving 

 the state of his opinion upon the point in question. 

 But, be it carefully noted, from this great or radical 

 difference of opinion between the joint originators of 

 the theory of natural selection, all their other differ- 

 ences of opinion arise ; and seeing that since the 

 death of Darwin a large number of naturalists have 

 gone over to the side of Wallace, it seems desirable 

 here to state categorically what these other or sequent 

 points of difference are. Without at present discuss- 

 ing them, therefore, I will merely set them out in a 

 tabular form, in order that a clear perception may be 



