1877.] The Colors of Animals and Plants. 647 
are some rare and little-known phenomena which prove that, in 
exceptional cases, light does directly affect the colors of natural 
objects, and it will be as well to consider these before passing on 
to other matters. 
A few years ago Mr. T. W. Wood called attention to the 
curious changes in the color of the chrysalis of the small cabbage 
butterfly (Pontia rape), when the caterpillars were confined in 
boxes lined with different tints. Thus in black boxes they were 
very dark, in white boxes nearly white; and he further showed _ 
that similar changes occurred in a state of nature, chrysalises fixed 
against a whitewashed wall being nearly white, against a red- 
brick wall reddish, against a pitched paling nearly black. It has 
also been observed that the cocoon of the emperor moth is either 
white or brown, according to the surrounding colors. But the 
most extraordinary example of this kind of change is that fur- 
nished by the chrysalis of an African butterfly (Papilio Nireus), 
observed at the Cape by Mrs. Barber, and described (with a col- 
ored plate) in the Transactions of the Entomological Society, 
1874, page 519. The caterpillar feeds on the orange-tree, and 
also on a forest tree ( Vepris lanceolata) which has a lighter green 
leaf, and its color 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 fodd~plant or of some neighboring tree, but it is probably 
often attached to larger branches; and Mrs. Barber has discov- 
ered that it has the property of acquiring the color, 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 thé 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 them- 
selves to the orange twigs, others to the bottle-brush branch, and 
these all changed to green pupx, 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 color; while one fixed itself 
_ just where the wood and brick joined, and became one side red, 
the other side yellow! These remarkable changes would per- 
haps not have been credited had it not been for the previous 
observations of Mr. Wood ; but the two support each other, and 
