Popular Science Monthly/Volume 15/June 1879/Observations on the Chameleon
|OBSERVATIONS ON THE CHAMELEON.|
By O. R. BACHELER, M. D.,
MEDICAL MISSIONARY AT MIDNAPORE, INDIA.
HAVING recently come in possession of a family of these interesting little animals, I have found both pleasure and instruction in studying their habits. Others of the lizard tribe are not averse to, and many seem to prefer, the vicinity of men, while the chameleon always seeks the deep jungle, away from observation.
A woman from the jungle who happened to discover their haunts has brought me at different times eight, one large and seven smaller ones, apparently of the same family. A large bird-cage keeps them securely, but they are turned out upon the grass, or placed on trees in the garden, for an hour or two daily, while a boy is employed to watch them, catch grasshoppers, and feed them. In the cool of the morning and evening they are not inclined to wander; but when the sun is hot. if they find that they are not watched, they are pretty sure to make for the largest trees, and then there must be a general turn-out of spare hands to look them up and capture them. As their quickest pace is only about five feet per minute, they are never able to get far away, unless too long neglected. There is great difficulty in finding them sometimes, even though we may know pretty nearly where they are, such is their adroitness in concealing themselves.
We have a small gardinia-tree, the top not three feet in diameter, and the foliage not dense enough to conceal one of them, and yet, after half a dozen of them had been placed upon the branches, I have looked for two or three seconds without being able to distinguish one, though on looking more intently I could see the whole without difficulty. So, to enable us to see them when they wander, we tie a bit of scarlet Berlin wool around their loins, which enables us to trace them easily. Sometimes when on the trees the scarlet wool may be seen bright in the sunshine when the little animals themselves are quite invisible.
The chameleon has been an object of curiosity the world over on account of its power to change its color, but its power to change its form is not less remarkable. Sometimes it assumes the form of a disconsolate mouse sitting mum in a corner; again, with back curved and tail erect, it resembles a crouching lion, which no doubt gave origin to its name, chamai-leon, or ground-lion. By inflating its sides it flattens its belly, and viewed from below takes the form of an ovate leaf. The tail is the petiole, while a white serrated line, which runs from nose to tip of tail over the belly, becomes the midrib. Still again throwing out the air, it draws in its sides, and at the same time expands itself upward and downward till it becomes as thin as a knife, and then viewed from the side it has the form of an ovate leaf without a midrib but with the serrate line of the belly and the serrated back becoming the serrated edges of a leaf. When thus expanded it also has the power to sway itself over so as to present an edge to an observer, thus greatly adding to its means of concealment.
I have studied the changes of color with much interest. In its normal state of rest it is of a light pea-green, at times blending with yellow. The least excitement, as in handling, causes a change. The groundwork remains the same, but transverse stripes appear running across the back and nearly encircling the body in a full-grown animal, numbering about thirty, and extending from head to tip of tail. These stripes occupy about the same amount of space as the groundwork, and are most susceptible to change of color. At first they become deeply green, and if the excitement continues gradually change to black. When placed upon a tree the groundwork becomes a deep green and the stripes a deeper green or black, and so long as they remain on the trees the color does not change. The prevailing idea, that they take on the peculiar hue of the foliage among which they happen to be, is, I think, erroneous. We have placed them on the scarlet leaves of the dracæna and among the red flowers of the acacia, with no change from the prevailing green.
My largest specimen measures from nose to tip of tail fourteen inches, the body and tail being about equal—the circumference of the largest part of the body about six inches. The legs are thick and muscular. The form of the feet, so far as I am aware, has no parallel in the animal kingdom. They resemble two hands placed palm to palm and divided to the wrist. The outer palm has three minute fingers armed with sharp, curved claws, while the inner has but two. Opened to its full extent it clasps a space of about two inches. Hands and feet are much the same, except that the feet are somewhat larger and thicker. The entire body is covered with armor. This consists of oval plates placed edge to edge. There are about nine hundred to the square inch, giving on my largest specimen, by estimate, thirty-two thousand plates. The color has its seat in the armor.
The tail coils up into a ring quite close to the body, when not required for use. The feet and tail have great power of prehension. The animal will clasp a branch with either so firmly that considerable force is necessary to detach it. Giving the tail a turn round a twig they will throw the body forward and grasp another branch a foot or more away, and so move from branch to branch. At night they hang themselves up, sometimes by the tail only, or by the tail and one or more of their claws, and so sleep.
The eyes are cones about. one fourth of an inch in diameter, one half projecting beyond the socket, completely covered with armor except at the point where the pupil is seen. This is about the size of the head of a large pin, set in a delicate ring of burnished gold. The eyes act independently of each other, the cones rolling freely in all directions, one often looking straight forward while the other is turned backward, giving them a most comical appearance.
The mouth is literally an open sepulchre. When opened you see a deep cavern almost down to the stomach, with no indications of a tongue. At the ramus of the lower jaw a deposit of whitish, gelatinous matter may be seen, covered with a thick, viscid mucus. On pressing upward beneath the jaws, a round, fleshy tongue is thrown up, a fourth of an inch in diameter and extending deep into the throat, the point of which is covered by the gelatinous deposit before mentioned, much like the swab on the rammer of a cannon. There are no teeth, but the edges of the jaws are serrated to serve the purpose of seizing and holding its game.
The lot of the chameleon is to live on trees and subsist on insects. Its motions are sluggish. It lies close upon a branch, assuming a form and color suitable to concealment, with its mouth wide open. Its viscid mucus serves to attract insects, and the moment they come in contact with it they are securely caught. When within two or three inches, the tongue is thrust out like a flash, the intruder is caught on the swab and drawn into the mouth. The tongue is then drawn down the throat, carrying the victim alive into the stomach. Beyond this we are not able to trace the process. We have seen grasshoppers to the number of half a dozen thus drawn in one after another.
Whether the change of color and form is voluntary or not, I have been unable to determine. From careful observation I am inclined to the opinion that it may be both voluntary and involuntary. Change of form seems to be quite under control, and change of color appears to be so at times.
Their intelligence seems to be of a very low order. After being separated they greet one another with open mouth and a hiss. They manifest no emotion, and no form of petting seems to be appreciated. Their instinct is to conceal themselves from observation, to climb to the highest available point, and to lie with open mouth waiting for their prey to come to them. The only activity they manifest is in the use of the tongue, and in this they are not excelled by any other animal.
In conclusion, we may notice some prominent marks of design and adaptation:
1. The power to change color and form affords the means of concealment.
2. The sharp claws and muscular power of feet and tail fit it for its abode on the branches of trees, often swayed and dashed about by the fierce tempest.
3. The tenacious mucus of its mouth attracts insects, while the darting tongue by the rapidity of its motion is an offset to the sluggishness of-the creature's movements.
4. Its armor-plates afford a protection from other marauders, and also from the heat of the sun and the inclemencies of the weather.
5. It is the friend of man, subsisting mainly if not entirely on insects that are injurious to vegetation.