Evidences of Theory of Natural Selection. 291 
presents it; but he also conceived a purely fictitious 
inversion of this truth, and wrote an essay to prove a 
statement which all the instincts in the animal kingdom 
unite in contradicting. 
This example will serve to show, in a striking 
manner, not only the distance that we have travelled 
in our interpretation of organic nature between two 
successive editions of the Excyclopeedia Britannica, but 
also the amount of verification which this fact furnishes 
to the theory of natural selection. For, inasmuch 
as it belongs to the very essence of this theory that all 
adaptive characters (whether instinctive or structural) 
must have reference to their own possessors, we find 
overpowering verification furnished to the theory by 
the fact now before us—namely, that immediately prior 
to the enunciation of this theory, the truth that all 
adaptive characters have reference only to the species 
which present them was not perceived. In other 
words, it was the testing of this theory by the facts 
of nature that revealed to naturalists the general law 
which the theory, as it were, predicted—the general 
law that all adaptive characters have primary reference 
to the species which present them. And when we 
remember that this is a kind of verification which is 
furnished by millions of separate cases, the whole 
mass of it taken together is, as I have before said, 
overwhelming. 
It is somewhat remarkable that the enormous im- 
portance of this argument in favour of natural 
selection as a prime factor of organic evolution has 
not received the attention which it deserves. Even 
Darwin himself, with his characteristic reserve, has 
not presented its incalculable significance ; nor do IJ 
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