698 



HISTORY OF THE SEA. 



Brass buttons were once fashionable which showed tne same 

 colors. They were made by having the polished surface ruled 

 with microscopically fine lines. It was, however, so costly 

 to make them, they cost a guinea each, that they were soon 



abandoned. 



Pearls are the secretion of nacreous material, spread, it is 

 supposed over some foreign substance which has been intro- 

 duced into the shell, under the mantle of the mollusk. When 

 the pearls are deposited on the shells, they generally adh<**e 



A SHELL CONTAINING CHINESE PEARLS. 



to it, when they originate in the body of the animal they art 

 free. As a rule some foreign body is found in their centre 

 which served as the nucleus for the deposit of the secretion. 

 It may be a sterile egg of the animal itself, or of a fish, or a 

 grain of sand, which was washed in. 



The Chinese and other nations of the East, take advantage 

 »{ this fact in natural history, for purposes of profit. They take 

 up the living mollusk, and opening the shell introduce into it 

 glas3 beads, or small metallic casts, representing some one of 

 their gods, or other objects, and then returning the mollusk %o 



