1825.] Mr. Gray on the Structure of Pearls. ^ 



slightly turning down the former part, and pushing the pieces 

 to some little distance by means of a stick, when the stop may 

 be withdrawn, and the animal will push the basis into a conve- 

 nient place by means of its foot, and of the 80 of 40 bases 

 which I thus introduced, only one or two were pushed out 

 again, and these I do not think had been introduced sufficiently 

 far. Jn several whicli I afterwards destroyed, I found that the 

 bases were always placed hear the posterior slope of the shell, 

 where the pearls are situated in the Barbala. 



If this plan succeed, which I have scarcely any doubt it will, 

 we shall we able to produce any quantity of as fine pearls as can 

 be procured from abroad. My reason for believing that this 

 manner of forcing the animals of the freshwater bivalves to pro- 

 duce pearls, is the invention of the Chinese, a nation celebrated 

 for their deceptions and trick, is that in looking over the col- 

 lection of shells of Mr. G. Humphreys, I observed that a shell of 

 this species (the second perfect one that I have seen) was 

 marked as having come from China. 



This plan at least is certainly much preferable to the one pro- 

 posed by Linneus, and by the above quoted anonymous author, 

 as the jiearls are all of a regular form, and that the one best 

 suited for setting. In cutting these pearls from the shell, 

 it is necessary that the shell should be cut through, so that the 

 mother-of-pearl button may be kept in its place ; for if the back 

 were removed, as it would be were not the shell cut through, the 

 basis would fall out, and then the pearl would be very brittle. 

 The only objection that can be adduced against these pearls is, 

 that their semiorbicular and unequally coloured sides preclude 

 them from being stiung, or used any other way than set; but 

 this fault will always be the case with all artificially produced 

 pearls, as the mantle can only cover one side of them ; and 

 the only pearls that well answer the purpose of stringing are 

 those found imbedded in the cells in the mantle of the "animal. 

 iVo/t'. — Since the above was written, my friend Mr. Children 

 has pointed out to me a paragraph in the EiK.-yclopedia Britan- 

 nica, vol. vi. p. 477, in which it is stated, " Pearls are also pro- 

 duced by another artificial process. The shell is opened with 

 great care to avoid injuriug the animal, and a small portion of 

 the external surface of the shell is scraped off. In its place is 

 inserted nspheerical piece of mother-of-peail, about the size ot a 

 small grai/i of shot. This serves as a nucleus, on which is depo- 

 sited tlie pearly fluid, and in time forms pearl. Experiments of 

 this kind have been made in Finland, and have been repeated 

 iii other countries." 



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