HAPTER OF CRITICISM. 
379 
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 the 
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 the 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 ope/randi; 
md 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 laminse, beginning 
with a small nucleus , and enlarging each successive layer, like a number of watch- 
;lasses,the smallest being the central one. These spherical laminse 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 
>f repairing the shell; unfortunately for their theory, the Pearl is generally 
bund lying snugly under the lower portion of the Muscle which connects the 
linges 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 
robable that the formation of Pearl bears a strong analogy to that of calculi , 
nd that they owe their peculiar beauty to their locality, being formed of 
similar substance (but in a more concrete and compact manner) as the inner 
urfaoes of the shells of both the Oyster and Muscle. It is possible—as I have 
een three or four different-sized Pearls from one Oyster—that they are the result 
f some solvent secreted by the fish, which acts on the nacreous portion of the 
hell, liquifying it; and as all fluids assume a spherical shape, more or less, the 
issolved pearly matter, obeying this law, takes a similar form, and, when hard, 
etains the partially spherical shape. Analogy is strongly in favour of this 
heory, as we find the biliary calculi in the human gall-bladder often nearly 
pherical, and they are nearly hollow; but even when so, their edges indicate 
