62 On ihe Economical Uses of some species of Testacetti 



They are found in the body of the animal, and not confined to 

 any particular part. Some contain but one, some a multitude of 

 small specimens, known by the name of seed pearls, while in the 

 shell itself, and protruding above the surface, are frequently circular 

 nodules resembling them ; as these must be cut, and on one side 

 are flat, they can only be used for setting, and of course are of less 

 value. They are technically termed by jewellers the wens of pearls. 



There is a common opinion that the animal may be forced to 

 produce the gems by artificial means. The inhabitants of the shores 

 of the Red Sea were said to have wounded them, and returned 

 them to the water; and the Chinese we are told insert beads of the 

 nacre into the shell, to be covered by the animal with the perlaceous 

 substance.* But these accounts from many obvious reasons are im- 

 probable, and we have not been able to meet in modern histories 

 with any authenticated instance of its having been done. In river 

 shells it might be more easily effected ; and we shall have to refer to 

 it again under the description of Mya margaritifera. They some- 

 times grow so large as to hinder the shell from shutting ; in which 

 case the fish dies,f and they are comparatively not uncommon of the 

 size of a small bullet. 



On analyzation, perlaceous shells appear to be formed of animal 

 ;matter, applied stratum upon stratum, with carbonate of lime be- 



* See Rees' Cyclopoedia; Encyclopceclia Americana, &c. &c. Art. Pearl. 



Beekman, in his History of Inventions, vol. ii. page 5, third Lond. Ed., seems 

 to have been the first in more modern times to have given extended publicity to 

 ;this opinion. He quotes as his authority a German work, and adds, that " the 

 truth of this information cannot be doubted." That it might happen, we do not 

 mean to deny, but sufficient authority is wanting to prove it, and many powerful 

 reasons are against it. How and when does the reader suppose the pearls were 

 inserted'? on a string containing five beads; and the clever Chinese caught the 

 shell when it rose to the surface in the spring to enjoy itself ! Of course next year 

 it had to be caught again to get at them, but how we are not informed. He has 

 however been servilely copied by most subsequent writers on this subject, with the 

 exception that he expressly says the shells are fluviatile, while his copyists confuse 

 them with, or describe them as the present marine species. Beekman confesses 

 that some experiments of the kind, made in Bohemia, were without success. 

 Postlethwaite gives an account in some respects similar, but still less creditable, 

 from a Chinese work. The pearl was made of several materials; among others, 

 nacre and bruised pearls, and the shell was kept in a basin, to be daily fed on me- 

 dicinal and gammy roots. He himself allows that it does not appear probable. 

 (See Postlethwaite's Dictionary, vol. ii. Art. Pearl.) It is time however that such 

 fables were exploded, and left out of works professedly scientific, and bearing on 

 the title page the name of some learned editor, assisted, as we are told, by " em- 

 inent professional gentlemen." 



t Chalmers' Universal Dictionary, Art. Pearl. 



