Men make use of something in nearly every branch of ocean life, from humblest to highest. The lowest of all, as I have already said, are the foraminifers; it is their skeletons which make up our common chalk. A close ally of theirs is the sponge, of which a dozen or so varieties are sold in the shops. Sponges come chiefly from the Mediterranean, the Persian and Ceylonese waters of the Indian Ocean, and from the Gulf coast of Florida. In the Old World they are obtained chiefly by diving. Men who are trained from boyhood to this work go out to the sponge-ground in boats on fine days. Fastening a netting-bag about their waists, and taking a heavy stone in their hands, they dive head-foremost to the bottom,—often twelve or fifteen fathoms below,—tear the sponges from the rocks, and rise with a bagful, to be dragged almost utterly exhausted into their boat, often fainting immediately after. This requires them to hold their breath under the water for two minutes or more; but none but the most expert can do that, and a diver does not live long. In Florida, however, the sponge-gatherers do not dive, but go in ships to where the sponges grow, and then cruise about in small boats, each of which contains two men: one steers, while the other leans over the side searching the bottom. In order to see it plainly, he has what he calls a “water-glass”—a common wooden pail the bottom of which is glass. Pressing this down into the water a few inches, he thrusts in his face, and can then perceive everything on the bottom with great distinctness. When he sees a sponge he thrusts down a long, stout pole, on the end of which is a double hook, like a small pitchfork, set at right angles to the handle, and drags up the captive. The sponges, having been obtained, must be put through long operations of rotting, beating, rinsing, drying, and bleaching before their skeletons—the serviceable part—are fit for use. Only a few, however, out of the large number of species of sponges have any commercial value. The limy skeletons of the coral polyps form what we term “corals.” The round white ones and the variously branching ones may come from any one of several parts of the equatorial half of the globe, and are of value chiefly as mantel ornaments. The red coral of which necklaces and other bits of jewelry are made, especially at Naples, is procured by divers about the shores of Sicily and Sardinia, and its gathering, cutting and mounting into ornaments, form a flourishing industry in southern Italy.