348 ANNUAL OF SCIENTIFIC DISCOVERY. 



a board having the impression. Pearls having these forms have excited much 

 surprise since they first attracted the attention of foreigners a few years back. 



The introduction of the pearl nuclei is an operation of considerable delicacy. 

 The shell is gently opened with a spatula of mother-of-pearl, and the free por- 

 tion of the mollusc is carefully separated from one surface of the shell with an 

 iron probe ; the foreign bodies are then successively introduced at the point of 

 a bifurcated bamboo-stick, and placed in two parallel rows upon the mantle or 

 fleshy surface of the animal. A sufficient number having been placed on one 

 side the operation is repeated on the other. Stimulated by the irritating 

 bodies, the suffering animal spasmodically presses against both sides of its 

 testaceous skeleton, keeping the matrices in place. This being done the 

 mussels are deposited one by one in canals, or streams or pools connected 

 therewith, five or six inches apart, at depths of from two to five feet, in lots 

 of from five to fifty thousand. 



If taken up a few days after the introduction of the mould these will bo 

 found attached to the shell by a membranous secretion which, at a later 

 period, appears as if impregnated with calcareous matter; and, finally, layers 

 of nacre are deposited around each nucleus, the process being analogous to 

 the formation of calculary concretions in animals of a higher development. A 

 ridge of marl generally extends from one pearly tumor to another, connecting 

 them all together. 



About six times in the course of the season several tubs of night-soil are 

 thrown into the reservoir for the nourishment of the animals. Great care is 

 taken to prevent goat manure from falling in, as it is highly detrimental to the 

 mussels, preventing the secretion of good nacre, or killing them, according as 

 the quantity may be great or small. 



In November the shells are carefully collected by the hand, the muscular 

 portion removed, and the pearls detached by a sharp knife. If the basis of 

 the pearl be of nacre it is not removed, but the earthen and metallic matrices 

 are cut away, melted yellow resin poured into the cavity, and the orifice art- 

 fully covered by a piece of mother-of-pearl. In this state these more than 

 semiorbicular pearly pellicles have much of the luster and beauty of the solid 

 gem, and are furnished at a rate so cheap as to be procurable by all who care 

 to possess them. They are generally purchased by jewelers and others, who 

 set them in tiaras, circlets, and various ornaments of female attire. Those 

 formed on the image of Buddha are finished in the same manner, and are 

 used as ornaments and amulets on the caps of young children. A few shells 

 are retained, with their adhering pearls, for sale to the curious or superstitious, 

 specimens of which have by this time found their way into the principal pub- 

 lic and private cabinets of Europe and America. They are generally about 

 7 inches long, and 5 broad, containing a double or triple row of pearls or im- 

 ages as many as 25 of the former and 16 of the latter to each valve. That 

 the animal should survive the introduction of so many irritating bodies, and 

 in such a brief period secrete a covering of nacre over them all, is certainly n 

 striking physiological fact. Some naturalists, indeed, have expressed strong 

 doubts as to its possibility, supposing the pearls were made to adhere to the 

 shell by some composition, but the examination of living specimens in differ- 



