396 



NATURE 



[May 26, 192 1 



The Japanese Artificially Induced Pearl. 

 By Dr. H. Lyster Jameson. 



ON May 4 a London evening paper announced 

 that quantities of artificially produced 

 Japanese pearls, of perfectly spherical shape, but 

 containing in their centres beads of mother-of- 

 pearl, had found their way into the London market 



Fig. I. — ectioii through the rentre 

 of a natural pearl, X 6i. 

 (Ordinary light.) Preparation 

 and photo by M.. A. Brammall. 



Fig. 2. — Section through the centre 

 of a Mikimoto pearl, X 6J. (Ordinary 

 light.) Mr. A. Brammall. 



and had deceived experienced pearl merchants in 

 Hatton Garden, who had bought and resold them 

 as naturally produced gems. Since that date 

 many inaccurate, misleading, and contradictory 

 announcements have appeared in the daily papers, 

 leaving the public, both lay and 

 scientific, in some confusion. The 

 following statement of the posi- 

 tion, so far as it can be judged 

 from the scientific point of view, 

 may therefore be useful. 



For some years Mr. K. Miki- 

 moto, the pioneer in the applica- 

 tion of scientific knowledge to the 

 pearl oyster oh a commercial 

 scale, has been producing in 

 Japan, and selling under the 

 name of "Mikimoto pearls," 

 pearls of this description. There 

 was no secret about this. Mr. 

 Mikimoto not only sold them as 

 artificially produced pearls, but 

 also published in one of his cata- 

 logues (No. 33) a short descrip- 

 tion and diagram explaining his 

 process. 



Ever since 1898 Mr. Mikimoto 

 (who began his work in collabora- 

 tion with the late Prof. K. 

 Mitsukuri in 1890) has been 

 marketing half -pearls or "blis- 

 ters," pearly excrescences formed 

 by inserting a mother-of-pearl bead between the 

 body of the oyster and the shell, and allowing the 

 oyster to coat it over with nacre. This was, of 

 course, merely a development C,f the very old 

 operation by which the Chinese produce, in fresh- 



NO. 2691, VOL. 107] 



water mussels, the well-known mother-of-pearl 

 images of Buddha, and of Linnaeus 's classical 

 experiments in the eighteenth century. These pro- 

 ducts were known as "culture pearls," and have 

 long been familiar in this country, set in brooches, 

 tie-pins, rings, etc. Their value, compared with 

 real pearls of corresponding sizes, was, of course, 

 quite small. 



For many years Mr. Mikimoto experimented 

 with a view to the production of a complete pearl, 

 not attached to the shell, by a modification of this 

 process, and obtained his first successful results 

 about 191 2, as announced by me at the Dundee 

 meeting of the British Association in that year. 

 From information supplied to me by Mr. K. 

 Ikeda, one of Mr. Mikimoto's staff, in a letter 

 from Tokyo dated May 30, 1914, it appears that 

 the first considerable crop of these "round culti- 

 vated pearls " was harvested in the autumn of 

 191 3. Their production is now an important part 

 of the original Japanese industry. 



Apart from the purely financial question as to 

 the degree to which the advent of artificially 

 induced pearls is likely to affect the price of 

 natural pearls, two questions seem to have been 

 agitating the public : Are these products 

 "pearls"? and Can a test be devised by which, 

 without destroying them, they can be distin- 

 guished from pearls of natural origin? 



Fig. 3 —Diagram illustrating the difference between a pearl (/.) and a blister (W.). s., substance of 

 shell; o.ep., outer shell-secreting epidermis ; p.s. pearl-sac, formed of shell-secreting epidermis; 

 ?.?/.,' inner ciliated epidermis of mantle cavity; par., 

 11 antle. 



parenchymatous connective tissue of 



Of course, when a slice is cut across a natural 

 pearl and a Mikimoto pearl the distinction is 

 obvious. A natural pearl, except In those (in my 

 experience exceptional) cases where a nucleus of 

 foreign origin and of sufficient size to be Identified 



