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to wait for? The fact that the variations which arise are 
not accidental, is another reason for affirming that this 
is not a sphere in which the action of Natural Selection 
is seen to the best advantage. 
This result of the study of defensive colouring has done 
more, as it seems to me, than any other branch of scien 
tific enquiry to remove the idea of the mystery which 
surrounds the origin of variation. So long as it was 
believed that there was a realm which was beyond the 
investigation of man, and which contained problems that 
he could not hope to solve, it served to discourage enquiry, 
and it enabled the advocate to say that Natural Selection 
was the only explanation. On this subject, Mr. Fiske 
says :— 
“Until after the publication of Mr. Darwin’s speculations, the 
colours of plants and animals had never been made the subject 
of careful and philosophical study. So far as any hypothesis was 
held concerning these phenomena, it was the vaguely conceived 
hypothesis that they are due to the direct action of such physical 
conditions as climate, soil, or food. But there are fatal objections to 
such an explanation. . . . But even supposing that the most 
general features of animal colouring could be explained on this 
hypothesis, which they cannot be, there would still remain the more 
remarkable cases of tree-frogs . . . and of the so-called leaf- 
butterflies ; . . . and the existence of such cases is a stumbling- 
block in the way of all theories save the theory of Natural Selection.” 
—(Cosmic Philosophy, vol. ii., p. 20-1.) 
The investigations which scientific men have recently 
made have surely withdrawn the veil of mystery from 
the process by which defensive colouring is produced. 
In the third place the favourable action of Natural 
Selection is in inverse ratio to the exercise of the intelli 
gence of the animal. This principle is maintained by Mr. 
Wallace, who contends that the intelligence of man arrests 
the effect of Natural Selection upon his physical frame ; 
and it is only an extension of this principle to assert that