PEARL, a peculiar product of cer tain marine and freshwater mollusks or shellfish. Most of the molluscous ani mals which are aquatic and reside in shells are provided with a fluid secretion with which they line their shells, and give to the otherwise harsh granular material of the shell a smooth surface, which prevents any unpleasant friction. The material in its hardened condition is called nacre by zoologists, and by dealers mother-of-pearl. Detached and gener ally spherical or rounded portions of the nacre are often found on opening the shells, due to the intrusion of a grain of sand or other substance, which, by irri tating the tender body of the animal, obliges it in self-defense to cover the cause of offense which it has no power to remove; and as the secretion goes on regularly to supply the growth and wear of the shell the included body constantly gets its share, and thereby continues to increase in size till it becomes a pearl. The true pearl of price is only found in the pearl oyster. The most famous pearls are those from the East; the coast of Ceylon or Taprobane, as it was called by the Greeks. They are, however, ob tained now of nearly the same quality in Panama in South America, St. Marga
rita in the West Indies, the Coromandel coast, the shores of the Sooloo Islands, the Bahrien Islands, and the islands of Karak and Corgo in the Persian Gulf. The pearls of the Bahrien fishery are said to be even finer than those of Cey lon.
The single pearl which Cleopatra is said to have dissolved and swallowed was valued at $400,000, and one of the same value was cut into two pieces for ear rings for the statue of Venus in the Pantheon at Rome. False pearls are manufactured extensively. The finest and costliest imitations could only be distinguished from the real by an expert. Roman pearls differ from other artificial pearls by having the coating of pearly matter on the outside, to which it is attached by an adhesive substance. The art of making these was derived from the Chinese.
The Chinese have long been in the habit of introducing grains of sand and little knots of wire into the shell of the pearl oyster, in order that the animal, to relieve itself from the irritation so caused, may coat the foreign substance with pearl.