WILD ANIMALS IN CAPTIVITY 



resting-place on which to undergo their transformations, 

 it follows that this photographic power in chrysalides is 

 most important, as tending greatly to make them invisible 

 during their period of exposure in a condition of utter 

 helplessness, which consists of from a few weeks to half-a- 

 year, and in some exceptional cases of more than a year. 

 The gilded chrysalides of Vanessidce and other genera are 

 extremely beautiful, and my opinion of their gilding being 

 a protection against birds has been confirmed by Mr- 

 Jenner Weir, who says that birds will not touch them, 

 evidently mistaking these chrysalides for pieces of metal. 

 I have noticed particularly that the chrysalis of the small 

 tortoiseshell ( Vanessa urticw) is golden only when found 

 among nettles, for when on walls, palings, tree-trunks, etc., 

 it invariably partakes of their colours and general appear- 

 ance of surface. The same remark may be made with 

 regard to the chrysalis of the large tortoiseshell {Vanessa 

 polychloras), which, when found amongst leaves, is of the 

 colour of a withered elm leaf, with a few silver spots ; 

 when, however, on walls, etc., the whole colouring is dif- 

 ferent, and the silver spots are absent. Now, it would be 

 no advantage to these chrysalides to assume the green 

 colour of the leaves, for they hang quite loosely by the 

 tail, with no band of silk to keep them close to their 

 surface of attachment, and the green colour would only 

 make them like tempting morsels to birds, etc. It is, 

 however, very remarkable that chrysalides belonging to 

 this genus are affected by green leaves so differently from 

 those of the generse Papilio, and Pieris ; the chrysalis of 

 the orange-tip, so remarkably lengthened in form, appears 

 to resemble the seed-pod of a cruciferous plant ; that of 

 Papilio podcdirms is coloured, ribbed, and veined like a 

 dead leaf " 



The undoubted fact of these creatures appearing to be 

 342 



