OSTREAim 
355 
The finest pearls, solidified drops of dew, as the Orientals term 
them in the language of poetry, are secretions supposed to be the 
r esult of disease in the animal. The matter, in place of being spread 
° v er the surface of the valves in their beds, is condensed either on the 
c entre of the valves or in the interior of the organ, and forms a more 
0r less rounded body. The pearls, when deposited on the valves, are 
generally adherent ; those which originate in the body of the animal 
Ur ° always free. Generally we find some small foreign body in their 
c entre which has served as a nucleus to the concretion, the body 
^eing perhaps a sterile egg of the mollusc, the egg of a fish, a 
bounded animalcule, a grain of sand even, round which has been 
posited in concentric layers the beautiful and much-prized gem. 
The Chinese, and other Eastern nations, are said to turn this fact in 
^ le natural history of bivalves to practical use in making pearls and 
c ameos. By introducing into the mantle of the mollusc, or into the 
^terior of a living valve, a round grain of sand, glass, or metal, they 
ltl duee a deposit which in time yields a pearl, in the one case free, 
ilrj d in the other adhering to the shell. In some cases they are said 
1(1 be produced in whole chaplets by the insertion of grams of quartz 
connected by a string into the mantle of a species of Symjyhynota ; 
other cases, a dozen Chinese figures seated have been produced by 
Verting small plates of figured tin in the valves of the same species. 
The pearls are very small at first ; they increase by annual beds 
^ e posited on the original nucleus, their brilliancy and shade of colour 
frying w itli that of the nacre irom which they are produced. Some- 
•Res they are diaphanous, silky, lustrous, and more or less irides- 
Cei d ; occasionally they turn out dull, obscure, and even smoky. 
„ The pearl oyster is met with in very different latitudes; they are 
^titl in the Persian Gulf, on the Arabian coast, and in Japan, in 
6 American seas, and on the shores of California, and in the islands 
ttie South Sea ; but the most important fisheries are found in the 
of Bengal, Ceylon, and other parts of the Indian Ocean. The 
I e ylon fisheries are under Government inspection, and each year, 
J ®*°re the fisheries commence, an official inspection of the coast lakes 
^ ace - Sometimes the fishing is undertaken on account of the State, 
other times it is let to parties of undertakers. In 1804 the pearl 
S)er y was granted to a capitalist for £120,000; but, (o avoid im- 
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