40 
Experiments on the Growth of Pearls , 
success, several of them died. I shall only relate what happened 
in the surviving ones. 
I drilled several holes in the most convex part of these shells, 
and introduced brass- wires of two-thirds of a line in diameter. 
These wires had a sharp point, and were fixed in the shell in the 
way of cramps; some were disposed in straight lines, and others 
in such artificial forms as to shew plainly that the pearls so pro- 
duced, if the experiment should succeed, were the work of de- 
sign, and not the unmolested operation of nature. One of these, 
which, I believe, is still preserved in the Anatomical School at 
Christ Church in Oxford, is an indisputable proof of this, the 
points forming the initial letters of my name. I let them down 
in a wooden box, perforated with holes, and loaded with a 
weight, into the River Isis ; and on examining them a few 
months after, I found some of them dead, and, it is probable, they 
died very soon after the operation, as the brass-points remained 
perfectly naked. I returned the living ones into the water, and 
took them up at the expiration of eighteen months from the ope- 
ration. I then killed the animal, in order to examine the shell, 
and I found, in one instance, the points of the wires fairly co- 
vered with a calcareous substance, rather coarser than the inside 
of the shell, which circumstance was probably owing to the 
more hasty deposition of the earthy matter, which, therefore, 
wanted the compactness and the pearly colour of the inner layer 
of the shell. Instead of points, the wires were now terminated 
by a round head, and the fish having survived, is a proof that it 
was sufficiently defended from the injury which it must at first 
have received. On examining other shells, I found the points 
of the wires, which projected at least two lines within the shell, 
covered only with a mucous substance, which, however, pre- 
served a rounded form ; so that this mucus, also, resembled 
the heads of large pins. 
In one shell, I found this mucus to be what I then suspected, 
the nidus for the deposition of the earthy matter, and one or 
two points observed with a magnifving-glass, shewed the earthy 
matter deposited in this gluten in the form of round opake white 
points, which would probably in a longer time have united into 
one mass, according to the usual process of ossification. This 
discovery led me to repent of having too hastily destroyed the 
