76 CLASS CONCHIFERA. 



When all the shells are thrown out, the slimy sub 

 stance of the oysters remains, mixed with sand and 

 broken fragments of shells, at the bottom of the vessel. 

 The dirty water is lifted out in buckets, and poured into 

 a sack, made like a jelly-bag, so that no pearls can be 

 lost. Fresh water being then added from time to time, 

 and the whole substance in the vessel continually agi- 

 tated, the sand and pearls together, are by degrees 

 allowed to sink to the bottom. 



As soon as the sand is dry it is sifted; the large pearls, 

 being conspicuous, are easily gathered ; but the sepa- 

 rating the small and diminutive (" seed pearls," as they 

 are called,) is a work of considerable labour. When once 

 separated from the sand, washed with salt water, dried, 

 and rendered perfectly clean, they are sorted into classes, 

 according to their sizes, by being passed through sieves. 

 After this, a hole is drilled through each pearl ; they 

 are then arranged on strings, and are fit for the market. 



Pearls have been considered as valuable ornaments 

 from the earliest times : they are mentioned in the book 

 of Job (xxviii. 18,) and are often alluded to by the clas- 

 sical writers. There have been various attempts made 

 to imitate them successfully, one of the most singular of 

 which, — known to have been practised early in the 

 Christian sera, on the banks of the Red Sea, — is still 

 carried on in China. A hole is bored in the shell of the 

 pearl-oyster, a piece of iron-wire inserted, and the oyster 

 restored to its place : the animal, wounded by the point 

 of the wire, deposits a coat of pearly matter round it : 

 this gradually hardens, successive layers are added, till 

 a pearl of the requisite size is formed, and the shell is 

 once more brought to land. 



A plan, somewhat similar to this, was tmployel by 



