Evidences of Theory of Natural Selection. 280 
cast-off shell of a mollusk; because the shell was 
primarily of use to the mollusk itself, and, so far as the 
mollusk is concerned, the fact of its shell being after- 
wards of a secondary use to the crab is quite immaterial. 
What Darwin’s challenge requires is,that some structure 
or instinct should be shown which is not merely of such 
secondary or accidental benefit to another 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 wcre 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 | happened 
to come across the 8th edition of the Aucyclopedia 
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 Evcyclo- 
peedia Britannica having been published shortly before 
The Origin of Species by means of Natural Selection. 
* U 
