her species, but clearly adapted to the needs
of that other species in the first instance--such, for example, as would
be the case if the tail of a rattle-snake were of no use to its
possessor, while serving to warn other animals of the proximity of a
dangerous creature; or, in the case of instincts, if it were true that a
pilot-fish accompanies a shark for the purpose of helping the shark to
discover food. Both these instances have been alleged; but both have
been shown untenable. And so it has proved of all the other cases which
thus far have been put forward.

Perhaps the most remarkable of all the allegations which ever have been
put forward in this connexion are those that were current with regard to
instincts before the publication of Darwin's work. These allegations are
the most remarkable, because they serve to show, in a degree which I do
not believe could be shown anywhere else, the warping power of
preconceived ideas. A short time ago I happened to come across the 8th
edition of the _Encyclopaedia Britannica_, and turned up the article on
"Instinct" there, in order to see what amount of change had been wrought
with regard to our views on this subject by the work of Darwin--the 8th
edition of the _Encyclopaedia Britannica_ having been published shortly
before _The Origin of Species by means of Natural Selection_. I cannot
wait to give any lengthy quotations from this representative exponent of
scientific opinion upon the subject at that time; but its general drift
may be appreciated if I transcribe merely the short concluding
paragraph, wherein he sums up his general results. Here he says:--

It thus only remains for us to regard instinct as a mental faculty,
_sui generis_, the gift of God to the lower animals, that man in
his own person, and by them, might be relieved from the meanest
drudgery of nature.

Now, here we have the most extraordinary illustration that is imaginable
of the obscuring influence of a preconceived idea. Because he started
with the belief that instincts _must_ have been implanted in animals for
the benefit of man, this writer, even when writing a purely scientific
essay, was completely blinded to the largest, the most obvious, and the
most important of the facts which the phenomena of instinct display.
For, as a matter of fact, among all the many thousands of instincts
which are known to occur in animals, there is no single one that can be
pointed to as having any