Page:Popular Science Monthly Volume 42.djvu/504

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THE POPULAR SCIENCE MONTHLY.

posed to the hot glare of the noonday sun, or seek a safe retreat beneath fallen logs or among the crevices of rocks. Its one idea is to warm up its cold blood by heat borrowed from the sun, and its life is one of apathetic indolence, except when in search of prey. Then the serpent steals stealthily through the grass; every now and again its slender neck elevates, and the cold, stony eyesPSM V42 D504 Skull of garter snake.jpgFig. 2.—Skull of Garter Snake. dart a hasty glance to right and left. The red tongue flashes forth two or three times and it renews the search. And now, down beside the mossy bank of the brook, it espies a luckless frog, unconscious of the gliding foe behind. The snake half coils, then springs, and seizes its victim in a viselike grip. Struggles only serve to drive in the little needlelike teeth deeper and deeper, for they are all pointed backward, as one may see by looking at the picture of the skull (Fig. 2). The serpent recoils, dragging the resisting prey more and more hopelessly away from its watery retreat. The method of swallowing is a very simple one, although, if the frog be large, more than half an hour may be consumed in the process. The two bones of the lower jaw are separate and capable of independent movement; so the reptile loosens its hold upon one side of its jaw, and, pushing that side forward as far as possible, it drives the teeth in again, and then draws the jaw back to its original position. The result is that the prey is drawn down by the movement. The process is then repeated by the other half of the jaw, thus inevitably forcing the victim inward. The snake's skin stretches enormously, and the jaw is, of course, dislocated, but the extensible ligaments hold the bones together. The disproportion between the diameter of the frog and the serpent's slender neck is indeed marvelous, and snakes have been observed to split themselves open by attempting too ambitious a mouthful. After perhaps half an hour of laborious contortions, all that is seen of the poor frog is a great swelling that the contracting muscles are rapidly forcing down the reptile's neck. If one liberates the captured frog before it is too late, the wretched animal often seems so overcome by fear, or perhaps stupefied by the serpent's saliva, that it will not leap, but crawls in a painful manner. We must not allow ourselves to be duped into a mistaken sympathy, however, for such is the poetic justice of the case. Large frogs