4 NATURAL HISTORY. 



changed into a pearl by the same operation of the se- 

 creted fluid which acts upon the shell, rendering it nacre- 

 ous and beautiful.* This supposition obtains generally, 

 as pearls are by no means found in every oyster. In 

 twenty oysters brought up from the depths of the sea, 

 very often not a single pearl is obtained, whereas, on the 

 other hand, sometimes twenty pearls are found in a single 

 one. The manner of fishing for pearl oysters is as fol- 

 lows : the divers, who are very expert, go out in boats 

 at the break of day to the spots where these oysters 

 abound; these boats are provided with stones which 

 weigh from fifteen to twenty pounds, and serve for 

 anchors. To accelerate his descent, each diver seizes 

 one of these diving-stones with his toes, at the same time 

 holding to the rope to which it is fastened, and which has 

 assisted him to go down ; this he keeps in his left hand. 

 No sooner has he reached the bottom, than he frees him- 

 self from the stone, collects the oysters as rapidly as pos- 

 sible, fills a net which hangs from his neck with them, 

 and gives a signal to be drawn up, as soon as he finds it 

 necessary to take a new inspiration. His mouth and 

 nose are protected by a sponge filled with oil, but it 

 often happens that on coming to the surface blood issues 

 from the mouth, nose, and ears, occasioned by the press- 

 ure of air upon their lungs in going down to the bottom. 

 The oysters are put into pens, and there left until the 

 animal matter decays, when the loathsome and unhealthy 

 business of washing the pure pearls from the putrid mass 

 commences. They are then assorted through various 



* All shells that are nacreous internally may produce pearls ; and 

 it is said that it is not uncommon to find them in a sort of large mus- 

 cle (unio) -which inhabits the great rivers of Europe and the United 



States. TV. 



