Page:Popular Science Monthly Volume 79.djvu/32

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discovered animals'-costume-scenery-counterfeiter not counterfeiting scenery, is any step at all toward finding out whether they all three do at certain times perform their tricks. Forty years of daily meeting the poacher at the post office does not strengthen his credit. And forty years of Roosevelt's seeing zebras not hidden by their costume, and failing to guess what the animal's stripes are for, are just as little to the point.

This effacing machinery is not the only highly specialized mechanism that animals carry always with them merely to have ready for occasional need. It is just the same with many of their other members and adaptations. The tiger's tremendous claws, if we estimate that he kills only once in two days, and that it takes perhaps four seconds for him to do it, are in operation only a 44,700-th of his life. Would Colonel Roosevelt for want of seeing them at their work decide that it was only a theory that they are for pulling down game? (I, by the way, do not even stop at the evidence that animals' costumes are for concealment. I point to the actual concealment in full operation.) The tiger's whole massive steely build serves him scarcely more constantly than do his claws. It, with the claws, does the pulling-down, and adds the bearing-away. The rattlesnake has a heavy rear body, growing slender and agile toward the head end, evidently in order that his terrible poison-apparatus may have a strong base to spring from. All this mechanism serves him only for occasional instants—days, weeks or months apart. Yet, there he always is, a heavy slow snake good only for lying in wait and for these rare murderous lunges, and totally incapable of the arboreal feats and racing of the black-snake's life. Would Roosevelt, because he so often sees rattlers not biting, hoot at the idea that this snake's fangs and build are made for biting? The generative organs of every monogamous species that breeds only once a year are carried through life for a few moments' function once a year—and so on and so forth. With costumes it is just as with all other adaptations. They may, according to their wearer's habits, play in his life a long part or a short one.

The particular herds and individuals of plains game that stood out so visible to Colonel Roosevelt were commonly those that happened to have the light behind them; and wherever any form of tree, shrub or very tall grass constituted an element of the scene, there were sure to be other herds and individuals in directions in which the illumination favored their counter-shading, wholly invisible amidst the haze of scrub and grass. A spectator in such a scene is surrounded with vast reaches of all-engulfing distance into which the haze of interposed scrub growth merges on every side. In these spaces a counter-shaded animal, when the direction of the daylight favors the working of his counter-shading, is already wonderfully matched to the scrub's color, and the