The Chameleon’s Colour

The Chameleon is a much-injured beast. He has been the topic of scandals as absurdly unfounded and as persistently credited, as if he had done mankind a great service — written a noble work, carved an immortal statue, invented a wonderful machine, or saved his country from peril.

I don’t know why fable should be so busy with him. I don’t know why he cannot be allowed even to eat like another animal; but must be said to feed on air. This, however, is but a small detail. Men will be curious and credulous; and if they hear that Tennyson likes the lean of mutton-chops, that Macaulay prefers his beef under-done, and Malais dines habitually of! pomegranates, they may like to hear and believe that the chameleon feeds on air. Such things will not disturb the digestion of men or saurians.

But it is otherwise when gossip trenches on the moral region, and character, not gustativeness, is at stake. The chameleon is said to be the most servile of animals, taking his colour by turns from every object he approaches. There are minds which Emerson has energetically characterised as “a mush of concession;” and the chameleon is falsely accused of having the same acquiescent disposition. It is false. The chameleon has his own colours, and sticks to them.

How then came about the general belief? How is it that the changing colours of the chameleon are proverbial? Do not press the question: the answer would be painful in its humiliation of human nature. Bather let us ask the Sages of Antiquity — who, having had the advantage of speaking the classical languages, must necessarily know more about everything than we, who speak a very barbarous and composite language, apparently not in the least worthy of the study of scholars — let us hear them explain the facts and causes of the chameleon’s colour.

And first hear Aristotle. Hats off, in presence of this really great thinker, and much-knowing naturalist! He knew that the animal sometimes was black, sometimes yellow, and sometimes spotted; and he thought these changes of colour depended on the swelling of its body, or on the death of the animal. Theophrastus, (hats on! ) attributed this change to fright: do not we change colour when terrified! Carystius said the colour was always taken from surrounding objects; an opinion repeated by Ovid, Seneca, and Pliny (the last-named a mere old woman in Natural History, who in virtue of his classical tongue, was regarded as an authority during several centuries), and which has from them become a popular error.

This is the classical ignorance on the matter. Let us now descend to moderns, or middle-aged moderns. Solinus copies Pliny; few did anything else in his day. Landius and Lord Bacon, without going so far, think that the colour grows darker when the animal approaches a dark object of the same colour as itself.

The once-renowned Peirese did what few of his predecessors thought necessary, he observed the living animals; and, of course, found out the error of the common belief. He found the ordinary colour of the chameleon to be green, or ashy grey, but it darkened under the influence of sun-light, or fire-light.

Towards the end of the 17th century two Egyptian travellers, Monsieur de Monconys, and Herr Johann Wessling, observed the living animals. The first noticed that the colours changed; the second noticed that in the morning and evening the animal was green; he blackened towards noon, grew pale towards night, and in complete darkness was white.

I forgot to mention, that Claude Perrault — the admirable Crichton of whom Boileau, with exquisite wit, and immense injustice, wrote:

II vivait jadis, a Florence, un medecin,
Savant hableur, dit-on, et celebre assassin,

among his multifarious activities included the study of natural history, and explained the change of colour in the chameleon as the result of a suffusion of the bile.

Vallisneri, a name dear to science, published a dissertation on the chameleon, in which, after criticising the opinions of predecessors, he proposed an explanation not unlike that proposed by Theophrastus. “It is the passions of the animal,” he says, ” which agitating it determine a rush of blood, humours, and vital spirits to or from the skin, and these make the skin reflect and refract the rays of light differently.”

Even Cuvier adopted this opinion, slightly modifying it. “The magnitude of the lung is probably the indirect cause of their changing colour, which does not take place, as is currently supposed, for the purpose of assimilating them to the nearest objects, but according to their wants and passions. The lung, in fact, renders them more or less transparent, by forcing the blood more or less into the vessels of the skin, the colour even of this fluid being more or less vivid according as the lung is distended with air.”

In 1827, the celebrated Dutch anatomist, Vrolik, ascertained the fact of the influence exercised by light on the colour of these animals; and he observed also that there was a constant succession, or oscillation, of colours. Four years later, his countryman, Van der Hooven (a translation of whose valuable “Handbook of Zoology” was recently published), executed the happy plan of reproducing in five different plates the changes of colour he observed. These show that the fundamental colour of the animal persists under all the variations which may take place in parts. He observes that the median line from the chin downwards is always of one yellow tint. In his opinion the changes of colour are due to a pigment underneath the skin.

This idea was taken up by Milne Edwards, who had two chameleons with different shades of colour: the one presenting violet spots on its flanks; the other, green spots of varying shade. He observed that the change of colour was quite independent of the animal’s swelling himself out or not. On removing a strip of skin from the dead animal, and placing it under the microscope, he observed that the darkest colour was beneath the tubercles, and that in these spots the yellow colour was masked, but not replaced: it still existed, although the violet spots beneath it rendered it invisible.

Two pigments therefore are possessed by the chameleon; one, the yellow pigment, being distributed over the surface; the other, the violet pigment, being distributed underneath the former, and only becoming visible under certain circumstances, such as the stimulus of light. Milne-Edwards found that, on stimulating the yellow spots with alcohol, or acids, they became violet; on stimulating the violet spots, they became yellow.

And thus after many centuries of easy fable, and iterated assumptions, the more arduous but more fruitful methods of exact Science gained the key to the whole mystery. But only the key. Milne-Edwards had explained the yellow and black hues; but had not explained the others. That was reserved for Professor Bruecke of Vienna, He succeeded to the satisfaction of men of science; but as it would require more technical knowledge to understand his explanation than can be expected of the ordinary reader, and would lead us to a length beyond our limits, we will merely add, that his observations show that the chameleon has his own colours, and does not borrow them from surrounding objects; if he sometimes shows more of one than of another, it is not that, like a negro maiden blushing, the emotions of his soul are eloquent on his surface, but simply that the rays of light act upon his skin.

After which explanation, it is hoped that we shall hear no more scandals about this much-abused Saurian.




About libros19blog

Central Florida
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