. The fishery resources of the Philippine Islands with descriptions of new species . Fishes; Fishery resources. 9i; SEALE. and that of the (Jeylon mother-of-pearl, as given by Herdman and Hornell ^° is— Calcium carlioiiiite Calcium sulphate ()rganic matter Water Loss (no magnesium, no pliospliates, faint trace of iron) It is well kiioMii that the organic basis of the shell, eonchiolin, is a eutieular product by the'underlying epideiinis of the mantle. without comment the many fanciful theories regarding the formation of pearls which have been held f
. The fishery resources of the Philippine Islands with descriptions of new species . Fishes; Fishery resources. 9i; SEALE. and that of the (Jeylon mother-of-pearl, as given by Herdman and Hornell ^° is— Calcium carlioiiiite Calcium sulphate ()rganic matter Water Loss (no magnesium, no pliospliates, faint trace of iron) It is well kiioMii that the organic basis of the shell, eonchiolin, is a eutieular product by the'underlying epideiinis of the mantle. without comment the many fanciful theories regarding the formation of pearls which have been held from historic times up to a comparatively lecent date, we will consider only sucli facts as have been revealed by modern scientific investigation. I have in my work dissected a large number of pearls from our large gold lip pearl oyster (i)/. maxima Jamson). Of this number, forty were prepared as "hard sections/' each side being ground down so that a small transparent section through the center of the nucleus was obtained for mieioscopic examination. (See Plate \, figs. 1 to 3.) Ten were prepared as microtninic sections, and the remainder, and by far the greatest number, were dissnlved in acids of various kinds and dissected. 'Vhi' results show that tlie round orient Philippine pearl may have various ob- jects in the center forming the so-called nuclei, which, tecanse of stimulation or irritation, have become incased in nacre, thus forming jx-avls. Fully "lO per cent of the pearls examined contained larval cestoiles, two only contained sand, one a liit of seaweed, one a spicule of calca- reous sponge, two, forms which with but little doubt were larval Disiomids. One rather interesting form (^ee lig. 'i) ob- tained from a perfectly round pearl ap- jX'iirs Neiy closely to le^emljle the free- swimming lar\al eeslodes secured by Mr. Hornell in Ceylon,^^ and is doubtless a related form. Se^eral pearls contained material that had become calcified and could not be identifi
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