Pearl Oysters and Hammer Oysters - Family Aviculidae the Wing Shells
Mother-of-pearl, the thick lining of each valve, is the de pendable product of pearl fisheries. It is secreted in annual layers by glands in the mantle. There is just enough animal substance in it to support the particles of lime carbonate. The iridescence is due to microscopic undulations of the various layers which compose it. These layers expose oblique edges to the surface, and the refraction of light produces the rainbow colours.
The best mother-of-pearl comes from healthy, full-grown shells ; the finest pearls from shells distorted by crowding and disease, and invaded by parasites and foreign particles. The first is a natural growth; the second abnormal. A lusty, well fed mollusk, enjoying life, has a neighbour, warped, debilitated, suffering, with a grain of sand rolling around in its mantle folds. Coat after coat of nacre is added to this irritating foreign body to lessen its injury to the tender flesh. When the diver finds it, a magnificent pearl, it makes him rich. Only one shell in a thousand, we are told, contains a gem of any value. So the lines of Browning would do little, I fancy, to reconcile a discontented pearl-diver to his hard lot: There are two moments in a diver's life: One, when a beggar, he prepares to plunge ; Then, when a prince, he rises with his pearl.
Throughout the seas of the equatorial regions are scattered pearl fisheries where thousands of people are engaged in diving for the pearl-bearing mollusks. Ceylon has ten, operated under government control. Nearest to us are the Panama and Lower California fisheries. Four to five thousand boats manned by divers work in the Persian Gulf each summer. The harvest of one year in this locality alone adds to the world's wealth in gems and mother-of pearl $2,000,000. This is the average, according to official statistics. The shells are smaller, but of better grade than those of Tahiti and of Panama. Australian fisheries pro duce small but very brilliant pearls. The Pacific Islands have many fisheries, noted the world over for their gems. The most famous pearls come from the Sulu Islands. Tahiti is the centre from which the products of the South Pacific fisheries are ex 395 The Wing Shells, Pearl Oysters and Hammer Oysters ported. Amsterdam, Hamburg, St. Petersburg, Paris. and Lon don are the great markets for these. Bagdad is the chief market for white seed pearls from the Red Sea and Persian Gulf. Bom bay distributes round pearls of yellowish colour, for which Hin dus have a preference.
White pearls are the most valuable, outranking yellow, green, pink and gray ones which are also held in high esteem, especially when two or more are perfectly matched. Globular pearls, free from flaws or discoloration, bring the highest prices. Pear-shaped ones rank next in value. Any form, so it be symmet rical and pleasing, is acceptable. Perfect pearls increase in price in geometrical ratio with increased weight and size. Pearls are not worked or polished, as most gems are. They are very soft, with a lustre nothing can improve.
No shells under five years old contain pearls of value. The growth of the sixth year doubles their value in mother-of-pearl. The seventh year again doubles it. The restriction of fishing' protects these young mollusks, and prolongs the life of the in dustry which, when unrestricted, exhausts the beds. In many places diving suits are never used, and dredging is forbidden by law. A famous Chinese fishery is worked one season, then it is left undisturbed for ten or fifteen years.
The pearl fishery at Bahreim, on the Persian Gulf calls to gether for the spring season, March, April and May, thousands of persons. The divers bring their families, and build huts of palm and bamboo. Boats carrying fifteen to twenty men go daily to the banks which lie under ten to twelve fathoms of water.
The diver is naked, his body rubbed with oil. He stuffs his nose and ears with cotton. A clamp is often worn on the nose. He carries a knife to fight off sharks, and to loosen the oysters. A basket hangs on his neck. He has a bar with a large shot at each end under his feet. He is framed by three wooden pieces attached to the loaded, bar. A rope lets this frame down and hauls it up in two minutes or less time. The diver has about seventy-five oysters. Fifty times a day he will take the trip.
The two great afflictions of divers are rheumatism and ulcers. The reward of this exhausting form of labour is a fluctuating, elusive thing. The uncertainty of it does not lessen its hold on the people who take it as a matter of course. The Ceylon fish eries give the diver one-fourth of his shells, divided when he 396 The Wing Shells, Pearl Oysters and Hammer Oysters comes up. Another plan is to pile the shells until they open, when the soft parts are thoroughly scanned for free pearls, which are the most valuable, and the shells are cleaned for shipment as mother-of-pearl. At this time the diver gets his share.
