tion of the difference between negative and positive evidence. I must confess that twenty failures to breed pearls would, to me, be quite set aside by one successful experiment—and so, I suppose, they would to the other members of this Society.
The scientific objections to the possibility of pearls "breeding" cannot however be overlooked. The oyster or mussel pearl is, as everybody knows, usually the result of a mucus secretion de- posited by the animal on some (it may be microscopic) foreign substance, though I believe this foreign substance is not always to be detected by analysis. Now under no conceivable circumstances can mucus breed mucus when it has once hardened into the lustrous nacre of a pearly surface. Without, as I have said, wishing to support any specific theory, I should be inclined to suspect that the pearls produced result from the labours of some insect which existed in the original oyster, and as a foreign irritant body caused the deposition of a pearly secretion; and it may be that this insect exists and breeds in rice under certain circumstances and that the original pearls have very little, or perhaps nothing, to do with the production of new ones.
Finally it may be worth while to cite another instance of an apparently incomprehensible freak of nature in a somewhat similar way. Mr. Frank Buckland, the well known naturalist, in the 2nd Volume of his "Curiosities of Natural History," relates (p. 128), that his attention was excited by an advertisement setting forth that an old China dinner-plate, which had been in the possession of its owner's family for nearly 300 years, had broken out in an eruption of crystals, the forms of which resembled shrubs, flowers, &c. It was put on exhibition at one shilling a head, and Mr. Buckland went to see it. "On examination with a magnifying glass," he says, "I observed numerous excrescences of a whitish opaque substance, apparently growing or extending themselves out of the centre and rim of the plate, each supporting upon its surface a portion of the actual enamel of the plate. The largest eruption (if it may be so called) is about the size and shape of a fourpenny bit, and it has raised up a portion of the enamel above the surface of the plate to about the height represented by the thickness of a new penny piece" Mr. Buckland then gives further particulars of this singular growth, concluding with the remark "I have not the slightest doubt that this is a natural production; that the material is of a mineral parisitic growth resulting from some chemical decomposition of the clay of which the plate was originally formed." Now, it will, I think, be allowed on all hands that the idea of a China plate 300 years old producing a "growth" of any sort is as unexpected and unexplainable a phenomenon as
