It may seem strange, but I believe this whistle is a mating-call. Even the forked tongue (or maybe the nose) of a snake grows vocal with love. If only the Sphinx had not possessed a heart of stone! No matter about its lips; with a heart to know the "spring running" we should have heard its story long ago. Perhaps, after all, the college sophomore was not mixing his observations and Sunday-school memories when he wrote, describing the dawn of a spring morning (I quote from his essay): "Beneath in the water the little fishes darted about the boat; above the little birds twittered in the branches; while off on a sunny log in the pond the soft, sibilant croak of the mud-turtle was heard on the shore." If we could happen upon the mud-turtle mad with love, I am sure we should find that he had a voice--a "soft, sibilant croak," who knows? I had long known the tradition among the farmers of the black-snake's trailing its mate, following her by scent through grass and brush, persistent and sure as a sleuth-hound, until at last she is won. I had been told of this by eyewitnesses over and over, but I had always put it down as a snake story, for these same witnesses would also tell me the hoop-snake story, only it was their grandfathers, always, who had seen this creature take its tail in its mouth and roll, and hit and kill a fifty-dollar apple-tree (the tree was invariably worth fifty dollars). I had small faith in the trailing tale. One day, the summer after my encounter in the ferns, I was sitting upon a harrow at the edge of the gravelly field that slopes to the swale, when a large black-snake glided swiftly across the lane and disappeared in the grass beyond. It had been gone perhaps a minute, when I heard another stir behind me, and turning, saw high above the weeds and dewberry-vines the neck and head of a second black-snake. He was coming swiftly, evenly, carrying his gleaming head over a foot from the ground, and following hard upon the trail of the first snake. He hit very near the smooth, flowing mark in the dust of the lane. Here she had crossed. Here he was about to cross when he caught sight of me. For a startled instant he stiffened, threw himself on the defensive, and showed a white patch under his chin, an ugly, blazing light in his eye, and a peculiarly aggressive attitude that there was no mistaking. I had seen this snake before. I knew him. He was the dragon of the swale. Only pausing, he whirled, struck the track, and sped on, his round black body stretching from rut to rut of the lane. A hundred feet beyond in the grass I saw his glittering head rise and sway with a swimming motion as he trailed the long, lithe beauty that was leading him this lightning race across the fields.