Page:Popular Science Monthly Volume 34.djvu/211

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throwing the main weight of the body on the padded cushion underneath the instep.

On the other hand, in the horse, adapted as he is by nature for scouring open, grassy plains or hill-sides, natural selection has favored the development of a particularly hard and solid hoof, whose native qualities man still further exaggerates by shoeing him with a clanking ring of iron; while in the camel, the direct product of desert conditions, a singular softness and pliability of foot has rather been encouraged by the soft and shifting nature of Saharan or Bactrian sands. For this reason, it is found practically that the horse and the camel are in any given country mutually exclusive; where the one thrives the other languishes. Here, in northern Africa, outside the Atlas, camels can not be profitably employed as beasts of burden; the few that come here in caravans from the desert arrive with a weary, foot-sore, dejected look, tired of tramping with their soft-padded feet over the hard and smooth macadamized roads which the French engineers have substituted for the narrow, paved Moorish packways, where mules and Arabs once transacted in their slow and lumbering fashion all the business of Algeria and Tunis. But beyond the shallow belt between the mountains and the sea the horse is of no avail: his hard and unyielding hoof sinks deep into the shifting sand of the desert, and he struggles and shuffles in helpless despair where the light dromedary, with his loose, shambling gait, his long trot, and his padded sole, fitting itself accurately to the sand beneath, accomplishes with ease his hundred miles a day for a week together. On hills or rocks the camel is nowhere, on open sandy plains he can hold his own against all comers.

It is interesting to note, indeed, how much alike in many adaptive particulars, but especially in their awkward gait, their tall necks, their long, shambling swing, and the powerful flanks which bring it about, are the three chief inhabitants of the desert or its outskirts—the camel, the giraffe, and the African ostrich. In the last-named case, the likeness is all the more curious and striking because one would almost have said beforehand that to adapt a bird and a ruminant mammal to the same environment, and to turn them out at last with many striking external resemblances of shape and gait, would be simply impossible; and yet Nature has accomplished this strange feat so perfectly that Linnæus, struck by the singular analogy between the two creatures, gave the ostrich the scientific name, which it still bears, of Struthio camelus. Even the reduction in the number of the toes to two, and their provision with a soft pad underneath, have been accurately reproduced in the great bird. As to the giraffe, its old name of camelopard sufficiently attests the popular appreciation of its outer similitude to the ship of the desert. The fact is, no