inoculating the edible mussel, Mytilus, by placing it with parasitically infected mollusks and thus artificially induced the formation of pearls. Herdman, in 1903, found in the pearl-oysters of Ceylon that a tapeworm larval cyst may become a pearl nucleus, or that in some cases the secretions may he deposited around sand grains, bits of mud or a fish or some other small animal, in pockets of the mantle epidermis, or again about calco-spherules near the muscle insertions. The surface finally becomes polished, or takes the "orient," and thus reflects the opaline and nacreous tints so highly prized.
The production of culture pearls dates back to the fourteenth century in China and it is probable that the Arabs had a similar industry. The Chinese open the shell of the river-mussel, push back the mantle and introduce metal images of Buddah which are covered with nacre in the course of six months. Linné drilled a hole through the shell and inserted a pellet of limestone on the end of a silver wire so that the nucleus might be kept free from the shell during the secretion of nacre. In more recent times the secretion of culture pearls has been induced in pearl-oysters by similar methods in various countries. Bouton, in 1897, at Roscoff, France, bored small holes through the shell of the abalone and inserted forms made of mother-of-pearl. After
