It seems that Linnæus’s discovery but verified the old saying that there is nothing new under the sun, for later it was announced[53] that in China—where so many inventions have originated—this idea had been put to practical account for centuries preceding, and the crafty Chinaman had succeeded in producing not only small pearly objects, but even images of Buddha, with which to awe the disciples of that deified teacher.
The method consisted in slightly opening or boring through the shell of the living mollusk and introducing against the soft body a small piece of nacre, molded metal, or other foreign matter. The irritation causes the formation of pearly layers about the foreign body, resulting, in the course of months or of years, in a pearl-like growth. While these have some value as objects of curiosity or of slight beauty, they are not choice pearls, nor for that matter were those produced by Linnæus.
It will be observed that the theory of Réaumur, and also that of Linnæus, required the intrusion of some hard substance, such as a grain of sand, a particle of shell, etc., to constitute a nucleus of the pearl; and this is the accepted explanation at the present time as to the origin of many of the baroque or irregular pearls, and likewise the pearly “blisters” and excrescences attached to the shell. But not so as to the choice or gem pearls, those beautiful symmetrical objects of great luster which are usually referred to in speaking of pearls.
Examinations of many of these have failed, except in rare instances, to reveal a foreign nucleus of sand or similar inorganic substance. In searching many fresh-water mussels, Sir Everard Home frequently met with small pearls in the ovarium, and he further noticed that these, as well as oriental pearls, when split into halves, often showed a brilliant cell in the center, about equal in size to the ova of the same mollusk. From these observations, in 1826 he deduced his “abortive ova” theory, and announced:
A pearl is formed upon the external surface of an ovum, which, having been blighted, does not pass with the others into the oviduct, but remains attached to its pedicle in the ovarium, and in the following season receives a coat of nacre at the same time that the internal surface of the shell receives its annual supply. This conclusion is verified by some pearls being spherical, others having a pyramidal form, from the pedicle having received a coat of nacre as well as the ovum.[54]