MAPTER OF CRITICISM. 879 



on the formation of Pearl. I consider the lecture very talented, and that it was 

 delivered in a masterly manner ; yet on the subject of the process by which 

 Pearls are formed, I am not aware that Mr. Lankester promulgated any thing 

 new. His statement was to the effect that the Pearl was produced when tfee 

 shell was injured, and that, therefore, this beautiful and delicate gem, so highly 

 prized, is the result of disease. This, I believe, is the generally-received opinion ; 

 but I have never met with a sufficiently clear account of the process of the 

 formation of Pearls, to explain their peculiar structure. I admit that they are 

 a secretion of gelatine mixed with nacreous or pearly matter, which, when com- 

 bined, impart to this substance its hardness, smoothness, and delicate brilliant 

 whiteness, rendering it so fit an ornament for the fair daughters of Eve, and 

 emblematical of the purity and chastity of their minds — the beings whom 

 Nature has formed in her choicest mould ! or, as the rustic poet has expressed it — 



" Her 'prentice hand she tried on Man, 

 And then she made *.he lasses, O.'' 



But to proceed. I have examined many Pearls, both from the Oyster and 

 the Muscle, making sections from them, in order to ascertain the modus operandi; 

 and before giving my own opinion on the subject, I would premise, that when the 

 Pearl is sawn through, the surfaces show a number of concentric laminae, beginning 

 with a small nucleus, and enlarging each successive layer, like a number of watch- 

 glasses, the smallest being the central one. These spherical laminae are all of similar 

 thickness, and in some instances may be easily separated. It is asserted by 

 naturalists, that the object of the fish in producing the Pearl, is for the purpose 

 of repairing the shell ; unfortunately for their theory, the Pearl is generally 

 found lying snugly under the lower portion of the Muscle which connects the 

 hinges of the shells ; and if produced early, prior to the full growth of the Oyster, 

 &c, the Pearl is often found imbedded in the flesh. From these facts, it seems 

 probable that the formation of Pearl bears a strong analogy to that of calculi, 

 and that they owe their peculiar beauty to their locality, being formed of 

 a similar substance (but in a more concrete and compact manner) as the inner 

 surfaces of the shells of both the Oyster and Muscle. It is possible — as I have 

 seen three or four different-sized Pearls from one Oyster — that they are the result 

 of some solvent secreted by the fish, which acts on the nacreous portion of the 

 shell, liquifying it ; and as all fluids assume a spherical shape, more or less, the 

 dissolved pearly matter, obeying this law, takes a similar form, and, when hard, 

 retains the partially spherical shape. Analogy is strongly in favour of this 

 theory, as we find the biliary calculi in the human gall-bladder often nearly 

 spherical, and they are nearly hollow ; but even when so, their edges indicate 



