Chap. VI. 
OEGANS OF LITTLE IMPORTANCE. 
199 
of the slight analogous differences between species. I 
might have adduced for this same purpose the differ¬ 
ences between the races of man, which are so strongly 
marked; I may add that some little light can appa¬ 
rently 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 
