284 MISCELLANEOUS OBJECTIONS TO THE [Chap. VII. 



resemble for the sake of protection special objects, but 

 only the surface which commonly surrounds them ; and 

 this chiefly in colour. Assuming that an insect originally 

 happened to resemble in some degree a dead twig or a 

 decayed leaf, and that it varied slightly in many ways, 

 then all the variations which rendered the insect at all 

 more like any such object, and thus favoured its escape, 

 would be preserved, whilst other variations would be 

 neglected and ultimately lost ; or, if they rendered the 

 insect at all less like the imitated object, they would be 

 eliminated. There would indeed be force in Mr. Mivart's 

 objection, if we were to attempt to account for the above 

 resemblances, independently of natural selection, through 

 mere fluctuating variability ; but as the case stands there 

 is none. 



Nor can I see any force in Mr. Mivart's difficulty with 

 respect to "the last touches of perfection in the mimi- 

 cry;" as in the case given by Mr. Wallace, of a walking- 

 stick insect (Ceroxylus laceratus), which resembles " a 

 stick grown over by a creeping moss or jungermannia, ,, 

 So close was this resemblance, that a native Dyak main- 

 tained that the foliaceous excrescences were really moss. 

 Insects are preyed on by birds and other enemies, whose 

 sight is probably sharper than ours, and every grade 

 in resemblance which aided an insect to escape notice or 

 detection, would tend towards its preservation ; and the 

 more perfect the resemblance so much the better for the 

 insect. Considering the nature of the differences between 

 the species in the group which includes the above 

 Ceroxylus, there is nothing improbable in this insect 

 having varied in the irregularities on its surface, and in 

 these having become more or less green- coloured; for in 

 every group the characters which differ in the several 



