CRYPTIC RESEMBLANCE IN PLANTS 103 



branchy, . . . and was at first mistaken for the dung of 

 birds of the passerine order. I have often had occasion to 

 remark that in stony place[s] there grow many small succu- 

 lent plants and abound insects (chiefly Grylli) which have 

 exactly the same color as the ground and must for ever 

 escape observation unless a person sit on the ground and 

 observe very attentively.' 



The cryptic resemblances of animals impressed 

 Darwin and Wallace in very different degrees, 

 probably in part due to the fact that Wallace's 

 tropical experiences were so largely derived from 

 the insect world, in part to the importance 

 assigned by Darwin to Sexual Selection, ' a subject 

 which had always greatly interested me,' as he says 

 in his Autobiography. 1 There is no reference to 

 Cryptic Kesemblance in Darwin's section of the 

 Joint Essay, although he gives an excellent short 

 account of Sexual Selection (see pp. 139, 140). 

 Wallace's section on the other hand contains the 

 following statement : 



'Even the peculiar colours of many animals, especially 

 insects, so closely resembling the soil or the leaves or the 

 trunks on which they habitually reside, are explained on the 

 same principle ; for though in the course of ages varieties of 

 many tints may have occurred, yet those races haviny colours 

 lest adapted to concealment from their enemies would inevitably 

 survive the longest.' 2 



It would occupy too much space to attempt any 

 discussion of the difference between the views of 



1 Life and Letters, i. 94. 



2 Journ. Proc. Linn. Soc., iii. 1859, 61. The italics are Wallace's. 



