Democratic Sentinel, Volume 20, Number 19, Rensselaer, Jasper County, 15 May 1896 — BIRTH OF A PEARL [ARTICLE]

BIRTH OF A PEARL

When the Oyster is Badly Tickled He Produces a Gem When an oyster feels something tickling his skin he does not— indeed, he obviously cannot—proceed to scratch the spot and apply counter-irritation, as a quadruped or a biped wotdd. The only course left to a mollusk in such a plight is to fence off his enemy with a layer or two of mother-o’-pearl, more sclentlflclally known under the term of “nacre.” In consequence of this many things happen inside 'the shell, among them pretty frequently the birth of a pearl. It should be known, moreover, to start with, that all the shell-bearing mollusks have the power of secreting calcite, which is a form of carbonate of lime, from the outer layer of cells, which forme the cuticle, or skin of their soft, not to say sloppy, bodies. In thi way they build up their shells. The limy secretion which they give off is laid in extremely thin, semitransparent films, and this is just the reason why the “nacre” is so beautifully iridescent, for very thin films have the property of producing what are scientifically known as ‘‘lnterference" effects and breaking ordinary light up into the colors of the spectrum. Now, if some tiny foreign body, such as a grain of sand, a “diatom," or even a minute shrimp or other crustacean happens to find its way inside the mantle border of the oyster, It sets up a good deal of irritation, and in self-de-fence the poor oyster is obliged to cover up the intruder by a layer of “nacre." So around the layer of sand, we will say, the mollusk goes on depositing thin layers of nacre one after the other, like the skins of an onion, until the point of irritation is completely/encysted and a pearl has been formed. This process is carried out. or attempted to be carried out, whatever the intruder may be, so that little fish have been seen incased in pearl within the bivalve’s shell. The Chinese, who never seem to neglect an opportunity to improve upon nature, have long taken advantage of this habit to artificially induce the growth of pearls by filling up the oyster with all kinds of irritating things. Ordinary pear-shaped pearls are excited by means of a tiny H-shaped piece of wire thrust into the mantle border, but it is not uncommon to insert little metallic images of the “great god Budh,” and subsequently obtain a cast of the same in pearl. These are much valued as charms. The finest Oriental pearls are those found within the mantle of the oyster close to the lips of the shell, or in the soft parts near to the hinge.