284 MISCELLANEOUS OBJECTIONS TO THE [Chap. VIL 



surrounding objects and the diversity in form and colour 

 of the hosts of insects which exist. As some rude re- 

 semblance is necessary for the first start, we can under- 

 stand how it is that the larger and higher animals do 

 not (with the exception, as far as I know, of one fish) 

 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 origi- 

 nally 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. Mi- 

 vart's objection, if we were to attempt to account for the 

 above resemblances, independently of natural selection, 

 through mere fluctuating variability; but as the ease 

 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 

 mimicry;" as in the case given by Mr. Wallace, of a 

 walking-stick insect (Ceroxylus laceratus), which re- 

 sembles " a stick grown over by a creeping moss or jun- 

 germannia." So close was this resemblance, that a na- 

 tive Dyak maintained 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 preser- 

 vation; and the more perfect the resemblance so much 

 the better for the insect. Considering the nature of the 



