214 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
the production of quaint pearl ornaments. One such compound 
mass I have seen worked into the form of a mulberry fruit, 
mounted with a spray of golden leaves. Other artists have 
utilized such masses in the production of grotesque figures 
when from time to time jewellery of this design is fashionable. 
True gem-pearls are those composed of lustrous nacre and 
of symmetric shape, round or pear-shaped preferably. These 
As will be seen later, these gem-pearls have frequently some 
foreign intrusive body as the nucleus, whereas the less valuabie 
pearls found in and around the muscle insertions have some 
particle produced by the oyster itself, as the centre of deposi- 
In all cases an envelope of secreting tissue—the pearl 
sac—surrounds the developing pearl. Inthe case of gem-pearls 
this arises usually as an invagination of the external epithelial 
layer, for the intrusive foreign body is generally found in th 
first instance between the inner surface of the shell and the 
secretory surface of the mantle. The latter being delicate 

___ Uyst-pearlsin number are relatively very scare as compared 
with muscle pearls, and large cyst pearls, the true gem-pearls, 
are again relatively much scarcer than small sizes. The former 
constitute the so-called Orient pearls, pre-eminent above all for 
their lustre and purity of colour and for a peculiar suggestion 
of translucency not seen in other pearls. 
: € origin of these pearls has been a battlefield of theory 
in the past ; the resultant confusion appears to me to be due 
in large part to the lack of recognition that there are these two 
main categories of pearls, differing in origin, and that in the 
