218 THE WORLD OF THE SEA. 
the intruding substance with its beautiful deposit. Thus artificial 
pearls are produced; in the one case they are loose, and in the 
other they appear as cameos fixed to the shell. 
A single pintadine sometimes contains several pearls. An 
instance is quoted in which 150 pearls were found in a single shell. 
The pearls at first are small. They grow by annual depositions of 
nacre, which are added layer by layer to the original nucleus. The 
clearness or cloudiness of the pearl necessarily depends on the 
A SHELL CONTAINING CHINESE PEARLS. 
nacre. Sometimes the pearls are semi-transparent, silky, lustrous, 
more or less iridescent, but often they are dull, and even smoky. 
The most important pearl fisheries are in the Persian Gulf, off 
the Arabian coasts, in the Bay of Bengal, near Ceylon, and in other 
parts of the Indian Ocean. Previous to 1795, most of the Indian 
fisheries were in the hands of the Dutch, but they became ours 
after the treaty of Amiens in 1802. The Ceylon fisheries are 
sometimes undertaken by the government, and sometimes they are 
let to a contractor. Before the commencement of the season, a 
covernment inspection of the coast takes place, in order that the 
banks may not be impoverished by too frequent fishing. The 
