MR. MIVART AND MR. DARWIN. 279 



resemblance" to the objects commonly found in the 

 station in which it is moving in its present differentia- 

 tion, requires more explanation than is given by the 

 word " accidental." 



Mr. Darwin continues : " As some rude resemblance 

 is necessary for the first start," &c; and a little lower 

 he writes : " Assuming that an insect originally hap- 

 pened 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, while 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." 



But here, again, we are required to begin with Natu- 

 ral Selection when the work is already in great part 

 done, owing to causes about which we are left com- 

 pletely in the dark ; we may, I think, fairly demur to 

 flie insects originally happening to resemble in some 

 degree a dead twig or a decayed leaf. And when we 

 bear in mind that the variations, being supposed by Mr. 

 Darwin to be indefinite, or devoid of aim, will appear 

 in every direction, we cannot forget what Mr. Mivart 

 insists upon, namely, that the chances of many favour- 

 able variations being counteracted by other unfavour- 

 able ones in the same creature are not inconsiderable. 

 Nor, again, is it likely that the favourable variation 

 would make its mark upon the race, and escape being 

 absorbed in the course of a few generations, unless — as 

 Mr. Mivart elsewhere points out, in a passage to which 



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