Sight is the great sense of the bird; scent is that of the fish. The Hawk, from above the clouds, pierces, with his glance, the deep space and marks the scarcely visible prey below; in like manner the Shark, from the depths of the water, scents his tempting prey, and darts upward upon it. Those that, like the Sturgeon, rummage the mud for food have exquisite touch. In the watery world half darkened, and having only uncertain and delusive lights, scent, and, in some cases, touch, must be relied on. The Shark, the Thornback and the Cod, with his great eyes, see badly, but have an exquisite sense of scent. The Thornback has that sense in such excess that he is provided with a veil for the express purpose of deadening it at will, when it probably affects his brain unpleasantly. To this powerful means of chasing their prey, we must add admirable teeth, sometimes like those of a saw. Some species have several rows of them, lining the mouth, the palate, the throat, and even the tongue. These teeth being so fine are, therefore, fragile; and behind, therefore, are others ready to replace them if they break. At the commencement of this second book, we said that it was necessary that the sea should produce these terrible and mighty destroyers to combat her own too great fecundity. Death by persevering excision and bleedings relieved her of a plethora which, otherwise, would have destroyed her. Against that alarming torrent of production which we have instanced in the case of the Herring and the Cod, those frightful multiplying machines which would have choked up the ocean and desolated the earth, she defends herself by the machine of Death, the armed swimmer, the fierce and voracious fish. Great, splendid, impressive spectacle! The universal combat between Death and Life, which we witness upon the land, fades into insignificance when we compare it to that which is going on in the depths of the sea. There, its surpassing grandeur, at first, almost alarms us, but when we examine more closely we see that all is harmonious and in marvellous equilibrium. That fury is necessary; that dazzlingly rapid exchange of substance, that prodigality of slaughter, are safety. Nothing of sadness, but a wild fierce joy seems to reign in all this. In this opposition in the sea of two forces, that seem so inevitably destructive of each other, the sea finds her marvellous health, her incomparable purity, and a beauty at once sublime and terrible. She triumphs alike in the living and in the dead, giving to them and receiving from them the electricity, the light which beams, flashes, sparkles everywhere, even in the long, dark, polar night. What is melancholy in the sea is not her carelessness to multiply death, but her impotence to reconcile progress with the excess of movement.