Page:Popular Science Monthly Volume 49.djvu/408

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390
THE POPULAR SCIENCE MONTHLY.

due to irritation of the terminal nerve filaments of the articular nerves.

M. Deroche thought he found that the muscular atrophy was due to diminution of interfibrillary substance, and that there was an ascending degeneration of the posterior columns on the same side. However that may be, the inference is certainly justifiable that massage acts to prevent muscular atrophy by maintaining an influence, a movement, or something in the muscles which the spinal cord is for a time unable to impart to them; and in order to do this, it should be applied immediately or soon after the injury, for then it is more quickly aroused from the lethargy and stupor into which it has been plunged by the shock of the accident.


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PEARLS AND MOTHER-OF-PEARL.

By CHARLES STUART PRATT.

AMONG the picturesque industrial possibilities of our southern Pacific coast is the artificial production of pearls. By this is meant, not the manufacture of artificial pearls, but the artificial growing of real pearls; that is, instead of the haphazard pearl-fishing of the present, the establishment, on the southern California coast, of oyster ranches, where the pearl-producing bivalves shall be scientifically directed and assisted in growing both gem pearls and mother-of-pearl.

This is hardly more visionary than was the recent establishment of ostrich ranches just inland from this same Pacific coast. A glance at the natural process of pearl-making will throw some interesting light on these oyster ranches-to-be. Mother-of-pearl is the natural product of the wild oyster, if we may so designate the bivalve of the unfenced sea bottoms. To secure a smooth surface for the contact of its soft, sensitive body, the oyster lines its coarser, rougher shell with a substance named nacre — which is simply carbonate of lime, with a trace of organic matter. This nacre is secreted and deposited in successive layers of filmy thinness and of marvelous smoothness of surface; the result is the lustrous, iridescent mother-of-pearl.

Unlike mother-of-pearl, the gem pearl, round or otherwise, is an unnatural product of the oyster. The gem pearl is an accident, almost a disaster, to its creator. In fact, a healthy, undisturbed oyster never produces a pearl. But if a sharp grain of sand finds its way inside the shell, the disturbed oyster protects its tender, sensitive flesh from the irritation of this offending substance by depositing about it smooth coatings of the nacre with which it has already formed or deposited the mother-of-pearl