rules."
As regards their origin, Professor Herdman classifies pearls into three
sorts : ( 1 ) "Ampullar pearls," which are not formed within closed
sacs of the shell-secreting epithelium like the others, but lie in
pockets or ampullae of the epidermis. The nuclei may be sand-grains or
any other foreign particles introduced through breaking or perforation
of the shell. (2) "Muscle pearls," which are analogous to gallstones,
formed around calcospherules at or near the insertion of the muscles.
And (3) "Cyst pearls," in which concentric layers of nacre are
deposited on cysts containing parasitic worms in the connective tissue
of the mantle and within the soft tissues of the body.1
Even
a particle of earth, clay, or mud may form the nucleus of a pearl. This
was illustrated a few years ago in a fine button-shaped pearl, which
was accidentally broken under normal usage and was found to consist of
a hard lump of white clay surrounded by a relatively thin coating of
nacre. More remarkable yet are the cases in which a minute fish, a
crayfish, or the frustule of a diatom has formed the nucleus.
Several
instances have been described by Woodward, Günther, Putnam, Stearns,
and others, where small fish have penetrated between the mantle and the
shell of the mollusk, and the latter has resented the intrusion by covering
the intruder with a pearly coating. In two or three instances the
secretion occurred in so short a time that the fish suffered no
appreciable decomposition, and its species is readily identified by
observation through the nacreous layer. Among the remarkable specimens
of this nature which have come under our observation are two very
curious shells received in March, 1907, from the Mexican fisheries. One
of these specimens shows an encysted fish, so quickly covered and so
perfectly preserved that even the scales and small bones are in
evidence ; indeed, one can almost detect the gloss on the scales of the
fish; and in the other—with a remarkable comet-like appearance—a piece
of ribbed seaweed is apparently the object covered.
From
the foregoing, it appears that the pearl is not a product of health
associated with undisturbed conditions, but results from a derangement
in the normal state of the mollusk. Unable to resist, to rid itself of
the opposing evil, it exercises the powers given to it by a beneficent
Creator and converts the pain into perfection, the grief into glory.
Nature has many instances of the humble and lowly raised to high
degree, but none more strikingly beautiful than this. One of the lowest of
earth's creatures, suffering a misfortune, furnishes a wonderful lesson
upon the uses of pain and adversity by converting its affliction into a
precious gem symbolical of all that is pure and
1 "Pearl Oyster Fisheries of the Gulf of Manaar," London, 1903, Vol. I, p. 10.
