Origin and fonnaiion of Pearls. 1 1 1 



receives its annual supply." While admitting that 

 an ovum may occasionally form the nucleus of a 

 nacreous concretion, we cannot admit the general 

 application of Sir Everard's explanation. 



The finest Pearls are found within the mantle 

 of the mollusc, close to the lips of the shell, or in 

 the soft part of the oyster near the hinge of the 

 shell ; the worst Pearls are those found within the 

 close, coarse fibres of the adductor muscle. At 

 very rare intervals they are found loose in the shell 

 outside the body of the oyster ; and may, when 

 large, get washed out of the shell and thus be lost. 

 Lastly, Pearls are often found imbedded more or 

 less deeply in the shell, having in some cases 

 escaped from the soft tissues. It is notable that 

 the adherent Pearls occur almost invariably in the 

 flat or lower valve: occasionally, it is true, they are 

 found imbedded in the rounded or upper valve, but 

 in such cases it is observed that the shell has been 

 lying at the bottom, in the reverse position, thus 

 making the rounded valve the lower one. This is 

 by no means an uncommon occurrence. 



The Pearls found imbedded in or under the 

 " muscular impression " are always small, irregular, 

 and worthless, similar to those found imbedded in 

 the adductor muscle itself. 



Pearls are found in infinite variety of form, 



