Chap. VI. OKGANS OF LITTLE IMPORTANCE. 199 



ignorance of the precise cause of the slight analogous 

 differences between species. I might have adduced for 

 this same purpose the differences between the races of 

 man, which are so strongly marked ; I may add that 

 some little light can apparently be thrown on the origin 

 of these differences, chiefly through sexual selection of 

 a particular kind, but without here entering on copious 

 details my reasoning would appear frivolous. 



The foregoing remarks lead me to say a few words 

 on the protest lately made by some naturalists, against 

 the utilitarian doctrine that every detail of structure 

 has been produced for the good of its possessor. They 

 believe that very many structures have been created for 

 beauty in the eyes of man, or for mere variety. This 

 doctrine, if true, would be absolutely fatal to my theory. 

 Yet I fully admit that many structures are of no direct 

 use to their possessors. Physical conditions probably 

 have had some little effect on structure, quite inde- 

 pendently of any good thus gained. Correlation of 

 growth has no doubt played a most important part, and 

 a useful modification of one part will often have en- 

 tailed on other parts diversified changes of no direct use. 

 So again characters which formerly were useful, or 

 which formerly had arisen from correlation of growth, 

 or from other unknown cause, may reappear from the 

 law of reversion, though now of no direct use. The 

 effects of sexual selection, when displayed in beauty to 

 charm the females, can be called useful only in rather 

 a forced sense. But by far the most important con- 

 sideration is that the chief part of the organisation of 

 every being is simply due to inheritance ; and conse- 

 quently, though each being assuredly is well fitted for 

 its place in nature, many structures now have no direct 

 relation to the habits of life of each species. Thus, we 

 can hardly believe that the webbed feet of the upland 



