346 TROPICAL NATURE 



This caterpillar feeds upon the orange tree, and also upon 

 a forest tree (Vepris lanceolata) which has a lighter green 

 leaf ; and its colour corresponds with that of the leaves it 

 feeds upon, being of a darker green when it feeds on the 

 orange. The chrysalis is usually found suspended among the 

 leafy twigs of its food-plant, or of some neighbouring tree, 

 but it is probably often attached to larger branches ; and Mrs. 

 Barber has discovered that it has the property of acquiring 

 the colour, more or less accurately, of any natural object it 

 may be in contact with. A number of the caterpillars were 

 placed in a case with a glass cover, one side of the case being 

 formed by a red brick wall, the other sides being of yellowish 

 wood. They were fed on orange leaves, and a branch of the 

 bottle -brush tree (Banksia sp.) was also placed in the case. 

 When fully fed, some attached themselves to the orange 

 twigs, others to the bottle-brush branch, and these all changed 

 to green pupae, but each corresponded exactly in tint to the 

 leaves around it, the one being dark, the other a pale faded 

 green. Another attached itself to the wood^ and the pupa 

 became of the same yellowish colour, while one fixed itself 

 just where the wood and brick joined, and became one side 

 red, the other side yellow ! These remarkable changes would 

 perhaps not have been credited had it not been for the pre- 

 vious observations of Mr. Wood ; but the two support each 

 other, and oblige us to accept them as actual phenomena. It 

 is a kind of natural photography, the particular coloured rays 

 to which the fresh pupa is exposed in its soft, semi-transparent 

 condition effecting such a chemical change in the organic 

 juices as to produce the same tint in the hardened skin. It 

 is interesting, however, to note that the range of colour that 

 can be acquired seems to be limited to those of natural 

 objects to which the pupa is likely to be attached, for when 

 Mrs. Barber surrounded one of the caterpillars with a piece 

 of scarlet cloth no change of colour at all was produced, the 

 pupa being of the usual green tint, but the small red spots 

 with which it is marked were brighter than usual. 1 



1 Mr. E. B. Poulton has since greatly extended these observations, both in 

 pupae and larvae, with very remarkable results. See Proc. of the Royal 

 Society, No. 243, 1886 ; Transactions of the Royal Society, vol. clxxviii. B., 

 pp. 311-441. These are briefly described in Darwinism, p. 197, and more 

 fully in a volume by Mr. Poulton on The Colours of Animals, 1890. 



