408 
with different tints, just before their change into the 
chrysalis condition. In black boxes they assumed a very 
dark colour; in white boxes they became nearly white. 
He also showed that a similar change took place in nature, 
the chrysalis placed against a white wall being nearly 
white, that against a red brick wall being reddish, and that 
against a pitched paling being nearly black. 
The caterpillar of an African butterfly feeds on the 
orange tree and a forest tree which has a lighter green leaf, 
and its colour corresponds with that of the leaves upon 
which it feeds. Mrs. Barber has discovered that it has the 
property of acquiring more or less accurately the colour of 
any natural object that 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 of the red 
brick wall, the other side of yellowish wood. They were 
fed on orange leaves, and a branch of the bottle-brush tree 
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 
and each corresponded in tint to the leaves around it, the 
one being a 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 the brick joined, and became one side red 
the other side yellow.* 
Change of organic colour may also be due to chemical 
action. 
“ Many of the complex substances which exist in animals and 
plants are subject to changes of colour under the influence of light, 
heat, and chemical change, and we know that chemical changes are 
continually occurring during the physiological processes of develop 
ment and growth.”—(Tropical Nature, p. 186.) 
Wallace. Tropical Nature, pp. là’j-g.