CREATION BY EVOLUTION
the wrist bones—is the longest and corresponds to the long bone in the human hand that extends from the wrist through the region of the palm to the base of the middle finger. If this single long bone in the horse is examined it will be found to.have on either side of it delicate splint bones, which lie in the flesh of this portion of the horse’s legs but which support no parts in particular (Fig. 5). In position these two splint bones correspond to the long bones of our second and fourth digits, but they are not continued as such in the foot of the horse. The splint bones of the horse’s foot are obviously remnants of other digits and are in the strictest sense of the word vestigial organs.
Turning to man we find him no exception to the rule that vestigial organs are abundantly present in the organization of animals. The external ear of the human being is a complicated fold of skin supported within by cartilage or gristle and occupying a fixed position on the side of the head. So far as hearing is concerned it is probably an organ of no great value. At least its occasional loss works no serious detriment to the hearing of its owner. But in listening for very faint noises we commonly extend the ear by holding a hand behind it, so that this organ probably serves somewhat as a collector of sound.
Notwithstanding the functional insignificance of the human external ear, this organ is provided with a rather remarkable group of muscles (Fig. 6). Extending from what may be called its root outward to the surface of the head are three considerable muscles, whose respective actions would be to bend the ear forward, upward, and backward. In addition to these muscles the surface of the ear proper has upon it six or more small muscles whose contractions would change slightly the form of the ear. All these muscles are well developed in the ears of certain lower animals, such as the horse and the dog, in which the three extrinsic
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