But that the main function of coloring is protection may be decided from the simplest observation of animal life in any part of the world. Even among the larger animals, which one might suppose independent of subterfuge and whose appearance anywhere but in their native haunts suggests a very opposite theory, the harmony of color with environment is always more or less striking. When we look, for instance, at the coat of a zebra with its thunder-and-lightning pattern of black and white stripes, we should think such a conspicuous object designed to court rather than to elude attention. But the effect in nature is just the opposite. The black and white somehow take away the sense of a solid body altogether; the two colors seem to blend into the most inconspicuous gray, and at close quarters the effect is as of bars of light seen through the branches of shrubs. I have found myself in the forest gazing at what I supposed to be a solitary zebra, its presence betrayed by some motion due to my approach, and suddenly realized that I was surrounded by an entire herd which were all invisible until they moved. The motionlessness of wild game in the field when danger is near is well known; and every hunter is aware of the difficulty of seeing even the largest animals though they are just standing in front of him. The tiger, whose stripes are obviously meant to imitate the reeds of the jungle in which he lurks, is nowhere found in Africa: but its beautiful cousin, the leopard, abounds in these forests, and its spotted pelt probably conveys the same sense of indistinctness as in the case of the zebra. The hippopotamus seems to find the deep water of the rivers--where it spends the greater portion of its time--a sufficient protection; but the crocodile is marvellously concealed by its knotted mud-colored hide, and it is often quite impossible to tell at a distance whether the objects lying along the river banks are alligators or fallen logs.