The Savannah morning news. (Savannah, Ga.) 1900-current, 1903-03-07
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ORIGIN OF PEARLS.
Due to n Worm il, the Oyster, of
Which 1t Is the Grave.


From the London Standard.
The current number of Nature con-
tains an account of DR.. Lyster jane
sons researches into the origin of the
pearl. Beautiful object as it is, the
animal that produces it probably re-
CARDS it as an unmitigated nuisance. 1t
is composed of a homely material-the
same that forms the inner part of the
nacreous layer of such a shell as the
common oyster, but gathered into a
ball, instead of spread out nearly
smooth. Thus, mother of pearl and the
pearl itself are of the same substance,
and their iridescence is due to the
waves of ordinary light breaking, as it
were, into sprays when they strike the
outcropping edges formed by these lay
erS. The pearl itself is secreted by a
part of the animal called the mantle.
and may be produced by other mollusks
than the pearl-oyster, which. strictly
speaking, is not an oyster at all. Brit
ish pearls, for instance, which,lwere
noted even before the days of Pliny
and Tacitus, with riVer-pearls general
ly, come from kind of freshwater mus
sci. The pearl really is a provision for
self-defenSe. When something obnox-
ious comes between the inside of the
shell and the mantle, the mollusk treats
it much as wise person does the pro-
verbal skeleton in the cupboard, when
he locks the door and loses the Key it
proceeds to bury the obnoxious inmate
beneath lays of nacre. The Chinese
avail themselves of this habit by deft-
ly inserting little fiat images of Budd-
ha, which. when thus encased. find a
profitable market, and some tiny irri-
tant causes the pimple-like pearls often
seen on the inside of a shell. The true
pearl, however, has not quite the same
history; it is formed inside the mantle,
and only becomes attached to the shell
by its exceptional growth for there is
worm in the pearl as we'll as in the
bud. The creature whose presence has,
in most cases, stimulated the mollusk
to make a pearl belongs to a very OBJ
jectionable class of worms those
known to science as the trematodes,
and in certain instances execrated by
farmers under the name of fiukes. The
higher grades in the animal Kingdom
hurry up. in passing through the low
er stages of their existence. but where
the dignity of the backbone is still in
the far future such a creature as one
of these, trematodes spends more time
over each sformation-perhaps, be-
cause, like some people having little to
do, it does it in a leisurely way. And
even then it must be helped. The trem-
atode, which u.s. so 10 say, at the bot
tom of the pearl, must have a host
a sort of foster mother-at each of It's
three stages of existence, and for one
of these win be content with nothing
less than vertebrate, This, then, is
its true story, as traced by DR.. Jane
son. 1t begins life-irt its lowliest form
"a mere germ-creature in the common
cookie or sometimes in the hardly less
abundant tapestry shell CTapes decus5
satus). There it remains till it reaches
the larval stage. Itthen' escapes, floats.
with the current till 1t drifts against
n living mussel. or other pearl-making
shell. It promptly pierces through the
body wall and settles down in its new
home. It's unwilling host resents the
intrusion. first by inclosing IL in a sort
of bag, and then with shelly material,
So the pearl Is the intruder's grave and
monument the beauty Of the lac
ter. as sometimes happens IN human
history Is greater than the merits Of
tie person cOmmem0rated. II this were
All. the suppIg ~ pearls would before
long be stopped. for the creature Is not
vet able 10 reproduce itself. Bur the
formation Of pearl Is rather SLOW
process, and sundrg birds ma shellnsh