34i 
But if Natural Selection sometimes takes a part in this 
business and sometimes does not, it is obvious that it is 
not an essential factor ; and, in short, that the modification 
of one part will lead to the correlated variation of other 
parts, whatever be the cause of the modification of the one 
part. Correlated variation is the ready ally of any trans 
forming cause which may operate on a particular part ; it 
is not, and it never ought to be represented as, the special 
coadjutor of Natural Selection. Even if Natural Selection 
did inaugurate such change, which there is some reason to 
doubt, it would only produce a result which is achieved by 
many other influences ; and when it came into action 
it would play, after all, only a very small part in the 
totality of the effect produced. 
Mr. Darwin further states that the results of correlated 
variation may be mastered by Natural Selection. 
“ These tendencies, I do not doubt, may be mastered more or less 
completely by Natural Selection. Thus a family of stags once 
existed with an antler only on one side ; and if this had been of 
any great use to the breed, it might probably have been rendered 
permanent by selection.”—(Origin of Species, p. nj.) 
Now it is quite clear that Natural Selection did not 
produce this exception to the rule of correlated modifica 
tion ; and, as there is no reason to suppose that one 
antler is more useful than two, there is no kind of proba 
bility that Natural Selection should have had anything to 
do with rendering such a modification permanent in a race. 
Moreover the perpetuation or the non-perpetuation of a 
variation like this depends upon its being inherited by 
offspring. But it is probable that such an exceptional 
phenomenon will not be inherited, the co-ordinated struc 
ture of the race asserting itself over the non-correlated 
peculiarity of the individual ; or, if inherited, it will tend 
to die out of itself, unless the variant should have the