Adaptive Mimicry. 67 



Now if we turn from the facts thus collected to some attempt 

 to co-ordinate or account for them, we are entitled to draw two 

 conclusions : — one, that the resemblances are designed for the 

 benefit of the creature ; the other, that they do not occur except 

 in cases where, owing to the absence of other advantages, they 

 may be regarded as distinctly necessary. But if we turn to the 

 cause of the phenomena, as distinguished from the end they serve, 

 we pass at once into the region of theory and conjecture. Omnia 

 exetmt in mysterium ; nor is it granted man to know the ultimate 

 cause of anything. The conjectures, however, which have been 

 put forward are three. 1. Tliat they are due in some unknown 

 way to similar conditions of food and external circumstances. 

 2. That they are the result of special creations. 3. That they 

 have resulted from that law of natural selection which tends to 

 " the survival of the fittest" in the struggle for life. 



1. The first of these theories may be dismissed as inadequate 

 and untenable, since (among other reasons) it disconnects the 

 adaptive mimicries from the obvious advantage of the species, and 

 thus makes them mere accidental lusus naturcc, — shewing no 

 possible connection between the supposed cause and the effect 

 produced. 



2. The second may indeed, in the present state of our know- 

 ledge, be regarded as possible, but it is one which in consequence 

 of the discovery of great secular laws, and the manifold results 

 known to be produced by their normal and continuous action, 

 comes with less and less weight to scientific minds. It is more- 

 over diflScult on this theory to account for the perfect graduation 

 which we find in these protective resemblances, to say nothing of 

 the fact that it is hard to conceive this deceptiveness, this masquer- 

 ading in nature, if it were the result of direct special creations. 

 It is hard, for instance, to imagine that a few rare species only 

 of Septalidae should have been created perfectly like the Heliconidse, 

 when it would have been so easy to secure their perpetuation by 

 other more simple and more universal means. 



3. Undoubtedly the third theory, which is in fact the doctrine 

 laid down by Mr. Darwin in his " Origin of Species," has the 

 greatest number of facts in its favour. No animal, except those 

 of Arctic origin is white, and of Arctic animals, all are white. 

 All wild hares and rabbits, for instance, are gre}', and in con- 

 sequence are able without diflSculty to lie hid amongst grass and 

 fern. But this cannot be from any natural animosity to whiteness, 

 for directly rabbits, rats, mice, &c.,are domesticated, white, and 

 black and white varieties are soon produced and multiplied. 

 What can we assume from this fact? Simply that in Arctic regions, 

 by the law of the selection of the fittest, {i. e., of those varieties 



