140 
DARWINISM 
CHAP. 
that they are inherited, and that they are constant. Ad¬ 
mitting that this peculiar appendage is (as Mr. Romanes says 
rather confidently, “ we happen to know it to he ”) wholly 
useless and meaningless, the fact would be rather an argument 
against specific characters being also meaningless, because the 
latter never have the characteristics which this particular 
variation possesses. 
These useless or non-adaptive characters are, apparently, of 
the same nature as the “ sports ” that arise in our domestic 
productions, but which, as Mr. Darwin says, without the aid 
of selection would soon disappear; while some of them may 
be correlations with other characters which are or have been 
useful. Some of these correlations are very curious. Mr. 
Tegetmeier informed Mr. Darwin that the young of white, yellow, 
or dun-coloured pigeons are born almost naked, whereas other 
coloured pigeons are born well clothed with down. Now, if 
this difference occurred between wild species of different colours, 
it might be said that the nakedness of the young could not be 
of any use. But the colour with which it is correlated might, 
as has been shown, be useful in many ways. The skin and its 
various appendages, as horns, hoofs, hair, feathers, and teeth, 
are homologous parts, and are subject to very strange correla¬ 
tions of growth. In Paraguay, horses with curled hair occur, 
and these always have hoofs exactly like those of a mule, while 
the hair of the mane and tail is much shorter than usual. 
Now, if any one of these characters were useful, the others 
correlated with it might be themselves useless, but would still 
be tolerably constant because dependent on a useful organ. 
So the tusks and the bristles of the boar are correlated and 
vary in development together, and the former only may be 
useful, or both may be useful in unequal degrees. 
The difficulty as to how individual differences or sports can 
become fixed and perpetuated, if altogether useless, is evaded 
by those who hold that such characters are exceedingly common. 
Mr. Romanes says that, upon his theory of physiological selec¬ 
tion, “ it is quite intelligible that when a varietal form is 
differentiated from its parent form by the bar of sterility, any 
little meaningless peculiarities of structure or of instinct should 
at first he allowed to arise, and that they should then he allowed 
to ‘perpetuate themselves by heredity,” until they are finally 
