MYTILUS MUSCLE. 191 



This species now forming the genus Melagrina, 

 is much celebrated for producing pearls. They 

 are thought to be occasioned by a disease in the 

 Mollusk, and to be produced by a partial 

 secretion of the substance of which it forms the 

 inner coating of its shell ; it is arranged in the 

 pearl in concentric layers. Acids, have the 

 same effect upon pearls as upon other carbonates 

 of lime, and Cleopatra is said to have dissolved in 

 vinegar one of great value in order to display 

 her magnificence by this costly draught. The 

 pearl fishery is a very dangerous employment ; 

 it is principally carried on in the Persian Gulph 

 and the neighbourhood of Ceylon ; the season 

 for the fishery lasts about a fortnight. Numer- 

 ous boats are dispatched to the station where it 

 is carried on, each containing twenty men, ten 

 of whom are employed in rowing and assisting 

 the divers. They descend alternately in parties 

 of five, and thus time is afforded for all to 

 recover themselves after their violent exertion. 

 The diver has a rope attached under his arms, 

 the end of which is given to the men in the 

 boat ; round his neck is slung a net, distended 

 at the opening by a hoop. Closing his nostrils, 

 he commits himself to the sea, with a perforated 

 stone of ten or twenty pounds weight affixed to 

 his foot, to accelerate his descent. He sinks 

 generally a depth of twenty or thirty yards; 

 then quickly proceeding to his work, he tears 

 the muscles from their bed, fills his net, makes 

 a signal and is drawn up again to the surface. 



