358 
THE OCEAN WORLD. 
Islands of Cubagua, Margarita, and Panama. The results became 
so full of promise that populous cities were not slow to raise them- 
selves round these several places. 
Under the reign of Charles V., America sent to Spain pearls valued at 
£ 160 , 000 ; in the present day they are estimated to he worth £ 60 , 000 . 
In the places mentioned, the divers descend into the sea quite naked , 
they remain there from twenty-five to thirty seconds, during which 
space they can only secure two or three piutadines. They dive JO 
this way a dozen times in succession, which gives an average of 
between thirty and forty bivalves to each diver. 
The bivalve is carried on shore, and piled up on mats of Espartero 
grass. The mollusc dies, and soon becomes decomposed ; it requires 
ten days to be thoroughly disorganized. When in a thoroughly 
corrupt state, they are thrown into reservoirs of sea-water, when they 
are opened, washed, and handed over to the dealers. The valves 
furnish nacre, and the parenchyma the pearls. 
The valves are cleansed, and piled up in tons or casks ; by raising 
their external surface plates of nacre are obtained more or less thick) 
according to the age of the mollusc. 
Nacre of three kinds are distinguishable in commerce : silver-facem 
bastard white, and bastard black. The first are sold in cases 0 
two hundred and fifty to two hundred and eighty pounds ; they ar ® 
brought from the Indies, from China, and Peru. The ships 0 
various nations import these shells as ballast. The second is delivered 
in casks of two hundred and fifty pounds weight ; it is a yellowish 
white, and sometimes greenish ; sometimes red, blue, and green. 
Pearls form by far the most important branch of this material- 
When they are adherent to the valves they are detached with pincers > 
hut, habitually, they are found in the parenchyma of the animal. 1° 
this case the substance is boiled, and afterwards sifted, in order to ob 
tain the most minute of the pearls ; for those of considerable size 
sometimes overlooked in the first operation. Months after the moll us0 
is petrified, miserable Indians may be observed busying themself 3 
with the corrupt mass, in search of small pearls which may have been 
overlooked by the workmen. . 
The pearls adherent to the valve are more or less irregular in the 
