CONCLUSION 803 



numerous successive, slight, favorable variations; aided 

 in an important manner by the inherited effects of the 

 use and disuse of parts; and in an unimportant manner, 

 that is, in relation to adaptive structures, whether past or 

 present, by the direct action of external conditions, 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 indepen- 

 dently of natural selection. But as my conclusions have 

 lately been much misrepresented, and it has been stated 

 that I attribute the modification 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. 



It can hardly be supposed that a false theory would 

 explain, in so satisfactory a manner as does the theory of 

 natural selection, the several large classes of facts above 

 specified. It has recently been objected that this is an 

 unsafe method of arguing; but it is a method used in 

 judging of the common events of life, and has often been 

 used by the greatest natural philosophers. The undula- 

 tory theory of light has thus been arrived at; and the 

 belief in the revolution of the earth on its own axis was 

 until lately supported by hardly any direct evidence. It 

 is no valid objection that science as yet throws no light 



SCIEXCE — 30 



