Page:Popular Science Monthly Volume 49.djvu/409

Rh lining of its shell. Layer after layer is added, until finally we have the round, lustrous gem for brides' fingers and the throats of queens.

It is possible that in some cases a wound throws off bony particles which become the nucleus of the pearl; or, in place of sand, the foreign substance may be a minute parasite, or a morsel of seaweed, or one of the tiny siliceous vegetables known as diatoms, or even one of the eggs of the oyster itself. Some such encysted particle, though perhaps of microscopic size, lies at the center, and was the cause, of every pearl. So the pleasure-giving gem is really the outgrowth of pain.

Now, it has been discovered that, instead of waiting the accidental intrusion of the alien particle into the shell of the oyster, grains of sand, or other objects, for the nucleus of the pearl, may be deliberately inserted by the hand of man, and that the oyster will at once set to work at pearl-making. It is known that the Chinese, from a remote period, have ingeniously taken advantage of this singular self-defense of the oyster. In the month of May the river mussels are taken from the water, and small pellets of clay, and even tiny images of the gods, are slipped inside the shells. The mussels are then replanted and left half a year. In November they are taken up again, and, while some of the shellfish die, most have coated the clay pellets and little metal gods with nacre, producing real pearls and genuine mother-of-pearl deities.

These mother-of-pearl Buddhas are in great demand with the curious and the devout, but there is no evidence that any of the priceless pearls of the world have been so produced. And yet surely the results obtained suggest great possibilities for the enterprising man who shall establish the oyster ranches already mentioned, and who shall add to the ingenuity of the Chinese all the resources of modern science.

The thin layers of nacre are always deposited thicker in depressions than over elevations; hence uneven surfaces become level, and small particles of whatever form gradually become spherical. The perfect round pearl, however, can only result when the nucleus penetrates the soft body of the oyster, or remains unattached to the shell. Often it does become so attached, and when removed has a defect on one side, and can only be used in settings where that side is hidden; such pearls are called boutons or button pearls; odd, irregular shapes are called baroques. Large or heavy intruding objects are quite likely to become attached to the lower half of the shell. Such objects often, in the course of years, are buried from sight under successive layers of nacre. Some Chinese Buddhas thus imbedded in the flat or lower halves of the bivalves are to be seen in London museums, and they