Page:Popular Science Monthly Volume 43.djvu/295

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goods. The national drink of the country—its wine and cider, there called pulque—is produced from this plant. When pulque not yet wholly fermented—then called agua miel or maguey juice—is properly distilled, an alcoholic drink called mescal is obtained. The plants are cultivated on a large scale in the lower and middle lands of which the agave is native, and the consumption and exportation have attained a great development. The maguey enjoys the advantage of flourishing where nothing else can grow; and immense tracts of sterile soil on the sea coast have been, under the stimulus of profit, made to produce remunerative crops. Yet the plant does not reject fertilizers, and those containing potash have been found very good. The elevation and climates of the several provinces varying considerably, many kinds of agave are cultivated, according to their adaptations, and have been given as many local names, which are Aztec or Spanish. Some ten varieties are adapted to produce fibers of henequen, or Sisal hemp—long, silky, elastic, and durable fibers suitable for rope-making or for coarse woven fabrics. Other varieties called lechuguilla in Mexico, having shorter and coarser fibers, furnish acceptable substitutes for hog's bristles in brush-making. These fibers are called istle or tampico. The thick and fleshy part of the root of some of these agaves—called amole—is used for soap, and when roasted furnishes what is considered a "savory food." The Agave americana is planted in Algeria for hedges. The dry flower stalks furnish materials for light buildings; and the pliant pith is made into insect paste and dressing for razor strops.

The Danger of the Celluloid Button.—An instance is related in England in which a lady was put in great danger while standing before a bright but not blazing fire by the burning of one of the fancy celluloid buttons of her dress. Experiments made by Prof. C. Vernon Boys prove that articles composed of this material are very susceptible to heat and take fire very readily. Prof. Boys advises the public to guard themselves from what is likely to be a grave source of harm, even to the extent of fatal issues, by taking the precaution of submitting to a very simple test that resembling tortoiseshell, hairpins, combs, and other ornaments, and toys. On briskly rubbing the button on cloth a strong smell of camphor is evolved. If this ready test fails, a small portion may be ignited; it will burn energetically with a flaring noise, and the fumes of camphor given off can not be mistaken. If the article is composed of other material, the smell will probably bring to remembrance that produced on burning feathers. Celluloid, it is said, may be made uninflammable and safe by mixing with it certain metallic salts—among them the chloride of tin.

Evolution of the Color of Birds.—Mr. Charles A. Keeler, of the California Academy of Sciences, has published a volume of 336 pages on The Evolution of the Colors of North American Land Birds. In explanation of how he arrives at the theories which he advances he quotes the experiments and researches of many celebrated scientists on the evolution of the colors of butterflies, goldfish, spiders, etc., and dwells particularly on the effects of climate and the laws of heredity—uninterrupted transmission, sexual transmission, and mixed or mutual transmission—as the chief elements in the evolution of the coloring of birds' plumage. Remarking, en passant, that the plumage of birds, confined or diseased, loses its brilliancy, and that, should the confined wild bird breed, the plumage of the offspring would be of less beautiful colors than the parent, Mr. Keeler cites Mr. Darwin, who says: "Each of the endless variations which we see in the plumage of our fowls must have had some efficient cause; and if the same causes were to act uniformly during the long series of generations on many individuals, all probably would be modified in the same manner." And in relation to the fact that there is a general constancy of coloration in the wild birds, he remarks that this uniformity of coloration is preserved by free intercrossing, and where this is prevented by isolation or migration, variations of color very frequently take place. Young birds of various species, after the autumn molt, continue through the winter to assume, by degrees, the more intense colors characteristic of the adults, without changing feather; and Mr. Yarrell says that many birds appear to become more brilliant in color as the breeding season approaches, without either molting or the