Page:Popular Science Monthly Volume 79.djvu/34

30 demand a "clean chipmunk"—i. e., an un-counter-shaded and un-dead-leaf-colored one—when the little beast dodges him. Note, too, that a grass-stained ball against the grass is, at its worst, far more conspicuous than an average chipmunk against the leaves, because the ball turns over, and therefore could not be counter-shaded. (Note also that predators in general are believed to miss far oftener than they succeed.)

Many familiar experiences prove this fact, that one's power to catch or hit a moving object depends on the distinctness with which one sees it. The more brilliantly a dodging object shows against the background, the more promptly can the brain of the pursuer command the corresponding movement. Those who have tried to catch butterflies, houseflies or mosquitoes, on the wing, or shoot a flying bird, either know this by heart or will realize it the moment they try it again. When a dark fly passes a dark space, to make sure of him you wait till he gets against a light space, and a shooter does the same with a bird. Throughout all nature animals' coloration proves to be such as minimizes, in the most wonderful way, to the eyes of their pursuers, their visibility when in motion. And in missing this fact" Colonel Roosevelt has missed a vast part of the whole wonderful subject. So true is it that, as he says, motion almost ensures detection, that it is no wonder we find concealing-coloration by far most constantly needed and at work—making the wearer as hard as possible to —where there is pursuit and flight. This matter would come home clearly to Colonel Roosevelt if he would try to hit a concealingly counter-shaded moving target against a background that it matched, and see what kind of a score he could make compared to what he could do with an un-countershaded one.

As soon as the public have been shown the astounding concealing-power of those African animals' reed-and-sky counterfeits, such as the zebra's and oryx's—which make it as hard as possible, by night as well as by day, for the springing feline to distinguish between starting zebra and jostled reeds—they will begin to see how complete has been their misconception of this matter. And the moment they see a demonstration of the magical working of facsimiles of these animals amidst reeds and branches, out-of-doors, they will see at a glance that it would be just so anywhere in the world. Colonel Roosevelt has confounded detection with catching. There is a vast difference. Every animal that has lived a year or two has been detected—how many thousand times—by other animals that would gladly have caught him; yet there he still is! Detection means, in some cases, much; but in far more case it means little. As Roosevelt evidently thought about the plains game, out in the open detection is nothing to them. He is also right when he says that these animals, zebras for instance, are sure to be observed by the ambushed lion as they nervously troop down to drink. The reader shall see how wonderfully their case bears out the hypothesis that all