MIND IN PROTECTIVE MIMICRY.
ACORRESPONDENT of the County Gentleman, in a discussion on the origin of the colouring of fox- hounds, quotes the opinion of a scientific zoologist that only one case is known in which large animals are aided by protective coloration. He also insists on the part which mind and intention play in securing protection for animals by assisting them to conform their attitudes to their sur- roundings. The two points raised in regard to the most attractive subject of protective colouring and its uses are not the same in kind. The question whether more than one large animal benefits by protective colouring is one of fact, and of the observation of field naturalists and sportsmen acquainted with the creatures when wild. That of the degree in which consciousness assists an animal in improving the advantages derived from protective likeness is less simple. How far they know what they are doing can only be a matter of conjecture and inference, the probable correctness of which must be supported by circumstantial evidence.
Naturally large animals require such aids to survival less than smaller and more helpless species. There is, however, a form of correspondence with environment which has for its object, on the same theory, the benefit of the species, to enable it to escape the notice, not of creatures who prey upon it, but of those which it preys upon. If the Polar bear were black, it would not have a chance of approaching its prey on the snow-covered ice. In the accounts of the behaviour of these bears in regions where man had seldom or never penetrated, it is stated that they tried to stalk the sailors, possibly taking them for seals, and crawled most carefully over the snow, taking advantage of every hummock and snow-pile. The only part of the bear which was conspicuous was the black end of its muzzle. This observation gave rise to the mariners' legend that the Polar bear, when working up to its prey, always covered its nose with one paw. At least two other of the most formidable carnivore, have this form of correspondence with surroundings in a marked degree. Many Indian sportsmen have noticed the difficulty of distinguishing the striped tiger in the long grass; and the resemblance of the alligator both to the river mud and the slimy corrugated bark of floating logs is equally striking.
The part apparently played by deliberate choice in making natural mimicry more effective may not necessarily imply that the animal is conscious of its likeness to its surroundings, and then goes on to improve on this by adapting its attitude to the particular lines most in harmony with the place in which it happen to be. But the action of the nightjar in sitting parallel with a branch, and even the common bittern in bringing the head and neck into a straight line, to conform with the vertical vegetation of the reedy marshes, very strongly suggests that mind plays a part in the act. Tracing these movements from their simple forms, it is certain that they are conscious efforts at first; the only question is of the degree in which the animal knows, or has inherited the knowledge of, how to make the best of its pro- tective advantages.
The commonest conscious device of animals for concealment is to crouch. It is done both by hunters and hunted. This in the case of animals like the hare, when they squat on open fallow fields, with only ridges and furrows to break the surface, is quite as much a conformity with the horizontal lines of the surrounding ground as the striking vertical attitude assumed by the bittern. But hares have another pro- tective device. Sometimes when surprised squatting on such a vividly coloured ground as a field of short clover buds they manage to break the colour of their fur by disarranging it, as if it had been brushed in different directions. The effect is peculiar, the colour of the lower fur very much non- fusing the whole and making it less visible. Mr. J. G. Millais noted in his " Breath from the Veld" that one of the large species of antelope when standing in the bush so poised its head and horns as to conform to the lines of the branches around it. As against the comparative rarity of these con- scious efforts among quadrupeds we find a considerable number of instances among birds. The hoopoe, not exactly the kind of bird which would be expected to seek conceal- ment, since it is brightly marked and flies well, squats and so arranges its feathers as to resemble a prickly plant com- monly found in its haunts. Some small Australian owls lately brought to this country used to assume protective atti- tudes whenever a stranger approached, though their plumage was already just like that of the bark of a tree. They threw back their heads and gazed straight upwards, motionless, draiving the head into the shoulders. The flat face thus gave the appearance of a broken stump, and the round eyes, being on a horizontal instead of a vertical disc, were not conspicuous.
That these actions were at one time rational in the higher animals, and are partly so still, seems very probable. But that they are now largely only transmitted experience may be inferred from the case of a white hare, which, though as easily seen as a bag of flour, squatted in the open as if it bad the same protective colouring as a normal hare. The protective imitations of attitude, form, and even of sound among insects are well known and astonishing. Among them the extremes of automatic and apparently conscious imitation are found. The green caterpillar of the privet hawkmoth changes its colour to suit the period of its descent from the bush. The green becomes dull, and turns to earth colour, so that when the caterpillar is entering the ground to change to a pupa the part of the body which sticks out of the hole it is digging gains the protective hue of the earth. As against this purely automatic protection we have the extraordinary case in which a Central African grasshopper when frightened arranged its wings to imitate a cobra's head and hood, and mimicked the serpent's hiss with the rattle of its wings There is such a thing in Nature as invisibility secured by mere shading. It is quite unlike mere pro- tective resemblance, and produces the effect on the mind of a trick. The arrangement at the Natural History Museum by which two models of birds, one plain white, the other white but shaded below, are set on the same line, shows this. At the distance of some eight paces the shaded bird is invisible, yet it is there, to be seen and felt, and if a shadow is thrown on the top of the invisible bird it becomes visible,—not by adding light, but by adding darkness. The late General Douglas Hamilton in his "Sport in Southern India" states that the tiger's stripes so correspond with the shadows of trees and grass-stems that it is almost invisible in places. Having wounded a tiger, he followed it, with two native trackers, to an open place with short grass and trees:—
"The sun was bright, casting the black shadows of the trees across the withered grass. We stood at the edge of this open space for some minutes, straining our eyes to see where the
tiger had gone, when suddenly one of the men said 'He dead' ; and there, not more than ten or twelve yards from us, lay the tiger stretched on the grass, stone dead ; but his black stripes and yellow body so exactly corresponded with the black shadows and yellow grass that none of us could make him out at first. Even in the open, at a few hundred yards distance, not a stripe can be seen on a tiger's body; I have often mistaken one for a deer."
The zebra's stripes, so conspicuous in captivity, obscure its outline at a distance and protect it, though, as Lord Dela- mere's photographs taken of wild zebras show, they are very conspicuous when some two hundred yards away. A curious instance of the invisibility of black-and-white stripes was noticed recently in a less obvious manner than in the chequer- ing of the forts in the Solent. A. party of ladies were strolling across a heath in the twilight after dinner; one had on a rather conspicuous black-and-white-striped dress. When the party were some eighty yards away, though the other dresses were distinctly seen, the wearer of this had become invisible.
That most of the dun and khaki coloured deer and antelopes, with lighter bellies, are indebted considerably to their colora- tion for protection no one will be likely to doubt. But this is very evident in the case of the dark mouse-coloured variety of the fallow deer. The wild fallow deer in Epping Forest are of this variety. In winter, among the thickly crowded mouse- coloured stems of the hornbeams and other trees, they are so exactly like their surroundings as to be most difficult to see unless they move.
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