Fig. 151.–Chamaeleon vulgaris. × ⅔.
A represents the usual coloration at night. The whole animal, which has just been stirred up from its sleep in the dark, is cream-coloured, with irregular patches of yellow on the head, the back, the sides of the body, the legs, and the tail.
B has the usual coloration: grey-green, with innumerable small darker specks, with two series of pale brown patches on the sides of the body, and with one patch on the region of the ear.
Fig. 152.–Showing changes of colour in Chameleons. A to D, Chamaeleon vulgaris (see p. [574]). Chamaeleon pumilus in the right upper corner.
C is the same specimen in an excited frame of mind; it is represented in the act of shooting a fly. The light brown patches have changed to maroon brown; and many round golden yellow spots have appeared on the green parts.
D shows a specimen, coloured like C, within a few seconds after it has been put into an angry mood, in the present case by having its tail squeezed. The whole body is blown out, the thick tongue causes the throat to bulge out, and all the yellow spots have become blackish green.
Many small spots scattered over the body are usually a sign of anger. One of the specimens described above was, when fast asleep in a dark room, dirty white, with about two dozen large and small round spots of a rich yellow on each side of its body. Then a lighted lamp was brought into the room without in any way disturbing the animal. Within sixteen minutes the yellow spots had vanished completely; the whole body and tail had become suffused with greenish yellow, which gradually turned to pale yellowish green, and those parts which in Fig. B are pale brown, were just distinguishable as pale yellowish-white regions. The Chameleon was found to be fast asleep, and it kept this coloration during the rest of the evening. Other specimens behaved on similar occasions in the same way, but the greatest interest is attached to the fact that frequently only that side of the body "greened up" which happened to be exposed to the light, whilst the opposite side remained whitish. These changes are not absolutely unconscious; they are, after all, under the control of the creature. In order to test the possibility of direct action of the light, I have taken the precaution of throwing the light of a candle only upon the body, whilst the head was kept in darkness. No changes of colour took place whilst the animal was asleep, but when a little light was allowed to sweep across the closed eye, this soon began to twitch, and although the creature did not open the eye, the usual changes of colour began to take place. When the light was removed, the animal soon re-assumed its whitish appearance. Artificially coloured light, for instance green, red, or blue glass or paper, has apparently no influence upon the changes of colour. The Chameleons behave as they would behave under ordinary conditions. Direct and hot sunshine however causes them to darken, sometimes to turn uniform dull black, except for the white median ventral line. Occasionally I found one of the specimens described above deep maroon brown, with dozens of round orange spots. Blue and red do not seem to be within the range of Ch. vulgaris, but the combinations of green, yellow, brown, black, and white, with their various shades, are almost endless. Sometimes the Chameleons do not turn pale during the night, but remain more or less dull green, with or without brownish patches. Adaptation to their immediate surroundings takes place to a very moderate degree only, but as a rule they are brightest, especially in their green tints, when they are allowed to sit amongst green foliage. The introduction of a branch with fresh leaves generally has a brightening effect upon those which have previously been confined in a cage with dry twigs only. Cold does not necessarily make them pale, but they appear duller, and the changes take place more slowly. After all, Linnaeus has summed up the little we really know about the causes of these changes, in the following terse sentence: "Vivus varios colores assumit secundum animi passiones, calorem et frigus."
Chameleons are not very amiable. When taken up they blow themselves out or they bite painfully, and it is a long time before they are tame enough not to go through various antics of anger when one approaches them. When taken in the hand they produce a peculiar faint grunting noise, which, however, can be better felt than heard. They quarrel much amongst each other; and the males, during the pairing season, are particularly ill-tempered. Each individual selects its own particular branch to sleep on, if possible a horizontal one, upon which it crouches down lengthwise, with the head and belly resting upon the branch. The tail generally makes a turn round another branch, and the four legs, grasping some supporting branch, are put into any, sometimes into an almost incredibly, awkward position. Although they climb about a good deal during the daytime, they generally resort to their accustomed sleeping branch, and they defend this vigorously against would-be intruders.