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Page:Popular Science Monthly Volume 24.djvu/587

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organic ingredients into their tissues. Of hyacinth-bulbs treated in a similar way, only the one treated with tannic acid developed roots. The hydrochloric-acid bulb died, and the sulphuric-acid bulb a month later. After the tannic-acid one, a bulb treated with oxalic acid did best. Tannic acid seemed to increase the intensity of the color of the flower. The plants were dwarfed by the treatment.


Temperature of the Glacial Period.—Mr. G. F. Becker closes a carefully considered review, in the "American Journal of Science," of the phenomena of glaciation with the conclusion that, if the generally received view (the substantiation of which would not be superfluous) that the sun is a gradually cooling body is correct, "it appears nearly certain that the absolute maximum in the development of glaciers is past, and that the glacial period was not one of general cold, but one of higher mean temperature at sea-level than the present." This is advanced without denying that a variety of other causes than those immediately considered by him may have had an influence, and, perhaps, a great influence, upon glaciation. "Indeed, it seems more probable that the formation of glaciers was affected by all contemporaneous changes, such as extraordinary upheavals and subsidences or periodic fluctuations in the eccentricity of the earth's orbit; but, if the reasoning offered is correct, it is not necessary to resort to such events to account for the occurrence of a glacial epoch." He believes that the production of glaciers is chiefly a question of differences between the temperatures at the sea-level and at the level at which the glacier is formed.


Pathology of the Pear.—At a meeting of the New Jersey State Microscopical Society, a paper was read by. the secretary, Dr. Samuel Lockwood, on "Fecal Sclerogen," the last word meaning the indurated particles of lignine in the pear. He showed a quantity of material like sand, which had been passed by a person to whom it had caused great distress. In the microscope it looked unlike any mineral sand, and each particle was composed of a cluster of sharp-pointed crystals, like dog-toothed spar. It even resisted the action of nitric acid, but was dissolved readily by ammoniuret of copper. Suspecting its nature, he took the rind and core of a ripe Bartlett, and gave them to his bees, which were suffering from a dearth of flowers. The insects cleaned away the glucose and all the juices, leaving the pear-grit clean; which, by comparison in the microscope, was identical with the fecal grit. The truth was, the person had been feasting inordinately on ripe Bartletts. The doctor remarked that it had never been cleared up why the pear should cause to many such suffering in the alimentary canal, as its juices were really far less acrid than those of the apple. He showed that it was due to the sclerogen, or pear-grit. Each particle literally bristles with sharp angular points, and the cathartic energy is due to the mechanical action irritating the walls of the alimentary canal.


Growth of Boys and Girls.—The investigations of the Anthropometric Committee of the British Association have made more or less clear several interesting facts respecting the rate of growth of the two sexes in the British Isles. The period of most rapid growth is from birth to five years of age, and then both sexes grow alike, the girls being a little shorter and lighter than the boys. From five to ten the boys grow a little faster than the girls, but from ten to fifteen the girls grow the faster, and at between eleven and a half and fourteen and a half years old are actually taller, and from twelve and a half to fifteen and a half are heavier than the boys. The boys, however, take the lead between fifteen and twenty years, and grow at first rapidly, but afterward slower, and complete their growth at about twenty-three years, while girls grow very slowly after fifteen years of age, and attain their full stature at about the twentieth year. The tracings and tables show a slow but steady increase in stature up to the fiftieth year, and a more rapid increase in weight up to the sixtieth year in men, but the statistics of women are too few after the age of twenty-three to determine the stature and weight of their sex at the more advanced periods of life. The curve of the chest-girth in men shows an increase at a rate similar to that of the