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 j)articularly that the chrysalis of the small 
tortoiseshell ( Vanessa urticm) 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 
‘polycliloras), 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 podalirnis is coloured, ribbed, and veined like a 
dead leaf.’ ” 
The undoubted fact of these creatures appearing to be 
342 
