THE PEARL
	These imperfections consist generally of dead white chalky spots and streaks, distributed over the surface of the pearl, oftentimes so small as to escape notice except under the loup. Some­times these imperfections take the form of rings or bands which encircle the pearl. Pearls so marked are rarely if ever round, but ovoid, capsule, or cartridge shaped, and these chalky lines always encircle the cylinder; they never cross the dome. Rings around the dome occur, but the surface over them is of equal luster. Frequently the entire outer skin is without luster. Whether this arises from lack of some element in the exudations of the mollusk from which the pearl is created, or from an imperfect crystallization of the calcium carbonate, is not known. Such skins have the usual nacreous surface wave lines and are often lustrous immediately under the outer plates of the skin. It is possible that these chalky skins may result from the extraction of the pearl from the mollusk during a transitional stage, and that the presence of spots and streaks of that character, scattered over an otherwise lustrous surface, indicates that the secretions of the creature's 114