PEARL fishery. The most important fishery to England at present is that at Ceylon. The origin of this method of procuring a valuable ornament for the person must have arisen from accidental ly discovering the pearl within oysters taken for food is evident ; but it is impos sible to ascertain when the search became systematical, though it is .extremely pro bable it has been so for many ages.
The pearl oysters of the coast of Cey lon are all of one species, and possess the same regularity of form ; but they assume different qualities, and have different de nominations, suited• to the nature of the ground where they are situated, and from the appearance of zoophytes adhering to the external surface of their shells. They resemble a cockle in shape, which is an imperfect oval, and their circumference is generally about nine inches and a half, having a segment as it were cut off where the joint of the two shells occurs. The interior of those is far more brilliant and beautiful than the pearl they enclose, and the outside is smooth, except when in jured by the usurpations of sponges, co rals, and other marine productions. The flesh of the animal is white, and of a glutinous consistency.
Perhaps no class of animated nature un dergoes more unmerited persecution and destruction than the pearl-oyster ; when situated in their native regions, they af ford a foundation for the habitations of other animals, and millions of them are dragged from their banks, and thrown away, for what they are vainly supposed to contain, and that an intruder or a dis ease. One of the banks at Ceylon fur nishes oysters to which zoophytes are at tached, apparently belonging to the class of sponges, and those generally resemble a funnel or cup, and grow to a size that completely overshadows the oyster : others of different banks have a substance adhering to them tinged with red. The above are found to contain the finest pearls : some escape free from incum brance, and thousands are compelled to bear trees of coral on them of five times their own weight.
The oyster is fastened to the rocks at the bottom of the sea by quantities of hairy fibres. By this means they are not
readily swept from their original station, and yet possess the advantage of being conveyed to some distance from it by the motion of the water ; besides, they are connected to each other in the same man ner. It frequently happens that an old oyster, surrounded by young ones, is brought up by the divers, and the latter have been ascertained to possess, even when little larger than a grain of sand, the power of moving themselves by the extension and contraction of what is term ed the beard. The violence of the waves at the time of the monsoons occasions great changes in the state of the banks, when incredible numbers of them are buried by the shifting of sand, and that is sometimes removed by the same power acting in a contrary direction.
It is supposed, from many concurring 'circumstances, that the pearl-oyster ar rives at maturity at the close of seven years : after this period it is imagined that it dies, when the body decaying is washed away by the sea : a bed was dis covered a few years since composed al most wholly of empty shells. The pre cious substance, which invites the exer tions of man to obtain it, has been gene rally supposed to be a disease peculiar to the animal ; but were this the fact, it is extremely prevalent amongst this de scription of oysters, as every individual of the species is found to be accompanied by a certain proportion of minute particles, which are evidently the pearl in the first stages of formation ; hence it may be fair ly supposed, that they are in some essen tial degree useful, rather than prejudicial to the inhabitant of the shells, of the na ture of which it decidedly partakes, and is composed of a number of layers, move able by a skilful person to the improve ment of the pearl, as it sometimes hap pens the exterior coat only may be dis coloured or injured. When the pearl is in a state of perfection, they are of a bril liant white, some have been found of a beautiful tint of pink, of the. colour of gold, and a few entirely black. These variations are, however, very uncommon.