The Formation of Pearls

B far the greater number of recent writers on pearls, whether “L'scientific or otherwise, when discussing the cause of pearl-formation, have contented themselves with recapitulating what has already been written on the subject, without attempting to verify or refute the various hypotheses that have been propounded.” The question is one which has called forth speculative theories since the earliest times of which we have any records; but, with the exception of the brilliant researches of Filippi and a few of his contemporaries, theory has prevailed to the almost complete exclusion of practical investigation. In a recent paper, based upon an examination of large quantities of material. comprising a number of the pearl-producing species of mollusca, I have tried to place our knowledge of the matter upon a more satisfactory basis.