78 CONCHOLOGIST’S COMPANION. 
a long series of adventures, is at present that famous 
pearl which adorns the top of the Persian diadem.”’ 
Many equally wild and extravagant opinions were 
advanced, to account for the formation of the pearl, 
by different European naturalists, and succeeded by 
others of a similar description, till the year 1717, 
when M. Reaumur, in a curious paper which ap- 
peared in the Memoirs of the French Academy, on 
the structure of both shells and pearls, conjectured 
with great probability (and his conjectures are now 
generally admitted), that pearls are formed of a juice 
extravasated out of some ruptured vessels, and 
detained and fixed among the membranes of the 
Oyster. 
To evince the probability of this Ingenious sup- 
position, he shews that oceanic and river shells are 
formed wholly of a glutinous and stony matter, which 
oozes from the body of the inhabiting Mollusca; and 
that, consequently, an animal furnished with vessels 
fraught with a sufficient quantity of stony juice to 
build, thicken, and extend a shell, is fully capable 
of forming pearl, if the juices designed for the in- 
crease of its habitation should chance to overflow 
among the membranes, or to fill up any accidental 
cavity in the body of the animal itself. 
In proof of which, he has further shewn, that 
when pearls of two colours are found in the Pearl 
