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181 
kinds of risk ; in which the occurrence of variations which 
are not accidental, in the sense of being simply variations 
due to sexual reproduction, is constant; in which intel 
ligence plays no unimportant part in securing the necessary 
advantages in the struggle for existence ; in which the 
stages of the process are variously described as very easy 
and very difficult; in which the enemy must be unob 
servant, and thereby becomes wonderfully quick-sighted ; 
or in which the victim continues to be observed and 
destroyed, so that no selection can take place. On the 
face of it, this can scarcely be the most favourable 
illustration that can be found of the effective action of 
Natural Selection. 
It is true that it is the all but universal opinion that 
all these phenomena have been brought about by Natural 
Selection. A great deal of careful observation has been 
brought to bear upon the subject, and most interesting 
experiments have been made ; but, so far as I can gather, 
no proof has been offered that the selection of favourable 
birth variations has brought about these results. Have 
we any evidence of a group of individual insects which 
have gone into a new habitat, and have remained alto 
gether unmodified during the life of the first generation, 
which have exhibited slight variations in the direction of 
protective colouring in a few individuals of the next 
generation ? Have we the direct evidence of actual 
observers that these variations, in a favourable direction, 
have been preserved, while the others have been destroyed. 
We have no such evidence that I am aware of. On the 
latter point Mr. Poulton speaks out very plainly when he 
reminds us that “very little of the destruction of life, which 
we know takes place, is actually witnessed by us.”* The 
The Colours of Animals, p. 224 —note.