PEARLS AND PEARL-MAKERS. 



49 



the mantle produces the outside, and from the body of 

 the mantle grows the rainbow lining. This wonderful 

 mantle, also, makes the pearl. 



For a long time it was supposed that the pearl mus- 

 sel and pearl oyster mold their gems about grains of 

 sand, or produce them when diseased. It is now the 

 opinion that some little animal gets into the mussel 



Pearl Oysters. 



or oyster and irritates the mantle. There is then let 

 out of the mantle a small sphere or drop of nacre 

 which increases layer by layer, until it reaches the size, 

 it may be, of a large bean. Both the pearl oyster of 

 the ocean and certain species of the fresh-water mussel 

 occasionally make pearls. 



One reason for the invasion of Britain by the Ro- 

 mans was said to be the attraction of its pearl fisher- 

 ies. In Irish and Scotch rivers large numbers of mus- 

 sels have been found containing pearls. In the year 



1865 these rivers yielded sixty thousand dollars' worth. 

 L. c.- 4 . 



