Page:Popular Science Monthly Volume 79.djvu/36

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plates of counter-shaded "vanished" models. He does not seem to take in at all the marvelous power of this counter-shading, which can actually efface the thing on which it is painted. And he has an idea that it chiefly affects the lower part of an object—as if it were merely a juxtaposition of dark top to white bottom, instead of a continuous gradation over the animal's entire surface. He says: "But as a matter of fact, the great majority of these mammals, when they seek to escape observation, crouch on the ground, and in that posture the light belly escapes observation, and the animal's color pattern loses very much of, and sometimes all of, the 'full obliterative shading of surface colors' of which Mr. Thayer speaks." Let Colonel Eoosevelt cover the lower half of one of our "vanished" models, in our book, and see if this cause the upper half to appear! Or let him cover the lower half of the visible monochrome model, and see if this cause the upper half to disappear.

Two more particularly flagrant errors of Roosevelt's must be mentioned. First, his speaking as if an animal's not trying to hide disproved his being concealingly-colored. He will in time discover that in a vast majority of instances, the very reverse is the case: that the more an animal doesn't hide, the more nature has to help him by coloring, precisely as in the case of the zebra at the drinking-place, or the humming-bird with his head stuck into a flower, or the flamingo at dawn with his head in the mud. Second, his much-insisted-on idea that if one coloration is a concealer, a different one on an animal of the same general habits isn't. He might just as well apply this objection to the mixed herds of diverse-shaped African game, of which so many species have closely resemblant habits, saying, for instance: "If the zebra is built right for this life, then it is a physical impossibility that the oryx is." Or to the innumerable forest plants, each with its own shape, but with, to the casual eye, identical circumstances. Or, concerning such a company of birds as feed together on the marshes, he should say: "These curlews, plover, and sandpipers live together and eat the same things; but if the curlew's bill is the right shape for his life, the very differently shaped bills of the other species are accidents and not adaptations." This is an old, obsolete method in natural history, henceforth to be succeeded by pure experimentalism. And I am presenting simply the experimentally established facts of these marvelous background-matchings. Amid sunlit snow and blue shadows the blue jay is exquisitely 'effaced' by its most perfect matching of each color-note. Likewise the peacock up in a tree, or the wood duck among sunlit water-plants, etc.[1] Each of these facts is here to stay, no matter where it leads us.

  1. One of the many surprises in store for Roosevelt is the potently obliterative character of the summer dress of the male bobolink, when seen from the hawk's viewpoint.