THE MILK POND OYSTERS. 67 



a pestilential stench. This fever lasted for two 

 months. Some adventurers found pearls, but the 

 greater number lost their time and labour. Jack 

 Minton was the only one to make his fortune, for 

 Milk Pond Bay was apparently the only locality 

 favourable to the development of the jewel.* 



* The liorny and calcareous matter (partaking equally of animal and 

 mineral characteristics) which the oysters apply to the walls of their 

 shells is known by the name of mother-of-pearl. The French call it 

 nacre, from the Arab word nahar — signifying a shell. When this 

 matter is very abundant it forms itself into little beads, which often 

 adhere to the interior of the valves, and are sometimes found lodged 

 within the fleshy folds of the mollusc. In the latter case, the pearls 

 are more spherical, and become enlarged every year by a fresh coat of 

 nacreous matter. They remain brilliant, translucent, and hard ; they 

 are what are called fine pearls. The nacre and the pearl are evidently 

 formed of the same substance, and only differ in the arrangement of 

 the layers. In the shell, the layers are horizontal, whilst in the pearl 

 they are curved and concentric. This form of structure attracts 

 luminous rays upon the surface so as to render it of a silvery bril- 

 liancy, at once dull and lustrous, very pleasant and beautiful to the 

 eye. A piece of the shell rounded artificially in imitation of a pearl 

 can never rival the brightness and beauty produced by the slow handi- 

 work of nature. The nacre owes the brilliance which is its chief 

 merit to the excessively thin layers of air which lie between the 

 calcareous and transparent leaves of which it is composed. The nature 

 of the pearl and its mode of formation lead one to suppose that these 

 precious concretions may be found in all shell-fish of which the interior 

 of the shell is made of nacre, whether they be oysters, limpets, 

 mussels, Venus's ear, &c., and, in fact, pearls are found in both the 

 common oyster and the mussel. The large fresh-water mussel which 

 is found in the mud of our rivers also produces pearls ; but the pearls 

 which are found in them usually resemble, both in shade and colour, 

 the interior of the shell in which it is found. The Ferine marine, a 

 species of mussel found in the Ked Sea, the Mediterranean, &c., and 

 which attains a great size, has a reddish interior to its shell, and pro- 

 duces rose-coloured pearls. This mussel furnishes also a greenish silk, 

 or fibre, which is called cyssus. The Sicilians and Calabrians spin it, 



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