260 FUNCTIONS AND INSTINCTS. 



miles long by twenty-four broad. The twentieth 

 of February is generally the day of rendezvous 

 for the fishermen. The fishery is commonly 

 rented by a single individual, who is allowed to 

 employ 150 boats for thirty days, there are 

 about 6000 boatmen and attendants. The 

 oysters vary in their qualities according to the 

 nature of the ground to which they are attached ; 

 and also in their number, by the action of 

 the tides and other circumstances : those at 

 the greatest depth produce the largest pearls, 

 which are situated in the fleshy part near the 

 hinge. Pearls consist of concentric coats of the 

 same substance as that which forms the mother- 

 of-pearl of the shell ; they are produced by the 

 extravasation of a lapidifying fluid, secreted in 

 the organs of the animal and filtered by its 

 glands. For one pearl that is found perfectly 

 round and detached between the membranes of 

 the mantle, hundreds of irregular ones occur 

 attached to the mother-of-pearl like so many 

 warts : they are sometimes so numerous that the 

 animal cannot shut its shell, and so perishes. 

 The pearl is a formation forced upon the animal 

 by some annoying substance in its shell, which 

 it covers with mother-of-pearl, as the bees do 

 intrusive wasps with wax, to fix it or hinder it 

 from affecting them by putridity, &c. Sir E. 

 Home is of opinion that the abortive eggs of the 

 animal are the nucleus upon which the pearl is 



