'S94-] 381 [Poulton. 
the rate of increase with its result, the struggle for existence. 
So that the three factors of natural selection are implied by the 
very words tliemselves. 
Now I want very briefly to bring forward the chief objec- 
tions that have been urged against natural selection. In the 
first place, if natural selection be true, all the varied characters 
of animals and plants must prove to be useful to the possessor 
in the struggle, or to have been useful at some time in its 
history. 
We are only required, however, to prove utility as regards 
undoubted characters of the species, and these are hereditary, 
and we must put on one side certain characters whicli are con- 
fined to the individual in which they appear. For instance, if it 
were proved that the Mollusca of any one river differed from 
those of the same species in another river, but that the differences 
were confined to the individuals in which they occurred, so that if 
these Mollusca were placed when young in the second river, they 
would come to x-esemble those which were proper to it, then we 
should not be concerned with characters of the species at all. 
The language spoken by a nation similarly is not a character of 
the human species, for we know that a child of another nation 
would acquire it perfectly together with the particular modes of 
thought and expression tortuous or direct which are associated 
with it. These results of environment are not characters of the 
human species. The individuals of the human species come into 
the world with a certain elasticity, a certain power of -being 
developed in various directions. But although the elasticity 
itself is a character of the species, and is inherent, the particular 
quality in which it may result when operated upon is certainly not 
a specific character. 
The more we work on the characters of animals in general, even 
though we at first can see no utility, the more we come to admit 
this principle, and to believe that either now or in some past 
time, the characters have been useful. I can certainly say of 
many characters which I have studied in some of my investiga- 
tions, that at first they seemed to be meaningless, but afterwards 
appeared to be of much importance in the struggle for existence. 
I think we may safely assume with regard to many characters of 
which we can now see no explanation that by and by the explana- 
tion will be fortlicomino-. 
