Page:Popular Science Monthly Volume 21.djvu/292

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282
THE POPULAR SCIENCE MONTHLY.

quent cause to admire the threads which he finds strung across the water-courses, and fastened to the trees on the opposite sides. The threads of these spiders are of different kinds, and proceed from different glands. The silk which is wrapped around the cocoons is not the same that is spun in the webs, and may be of an entirely different color. The silks of various Epeiræ were brought to Europe by travelers in the seventeenth century, and excited admiration by their fineness and brilliancy. Experiments were tried in making cloth and gloves from them, but they were found to have no powers of endurance. Louis XIV, wishing to encourage a new art, had a coat made of the silk, but was glad to take it off the first day, for it suffered a rent every time he moved. These efforts appear to have been made with the silk of the webs. That unrolled from the cocoons proved to be stronger. M. Bon, in 1709, carded from the cocoons a silk which he described as much finer and stronger than ordinary silk, and which, he claimed, was fitted to make any kind of fabrics. In Spain, Raymondo María de Tremezer, between 1777 and 1791, made several articles as bright and fine as silk from the threads of the Epeira diadema. Mr. Rolt, an English merchant, was able to exhibit to the Society of Arts a specimen thread twenty thousand feet long, that had been spun by twenty-two spiders in less than two hours, and which was five times as fine as the thread of the silk-worm! Alcide d'Orbigny asserted that he had garments, able to sustain considerable wear, made in South America from spiders' silk.

 

Food and Civilization.—M. Beketoff, a Russian hygienist, has expressed some novel views in a paper on "The Alimentation of the Human Race in the Present and the Future." Physiologists are accustomed to consider a mixed diet, of which meat shall constitute about one third, to be the best for mankind in general, and to be almost essential to the best development. M. Beketoff does not consider this view to be well founded, or sustained by the facts as they appear on examination of the diet of the best races. A large majority of mankind do not use meat, nor a mixture of meat and vegetables, but vegetables alone, as food. The people of Europe consume more meat than those of any other part of the Old World, but most of it is used in the cities, while the country people enjoy only a small fraction of the quantity which the physiologists say they need, and it has come to that point that, in the most civilized part of the world, meat is only not wholly left out of the list of common foods. In the most populous and most civilized parts of Asia, as in China and India, cattle-raising is quite insignificant, and in Japan can hardly be said to exist at all. The Africans raise cattle, but live chiefly on vegetables. Only in North and South America and Australia is meat consumed on a really large scale. Not only the relative, but the absolute number of cattle also, shows a tendency to diminish as the population increases and the ground is more devoted to tillage; so that the prospect is apparent that, with the continuous development of agriculture, industries, civilization, and population, cattle-raising will pass into real insignificance, and the mass of men will be unable to obtain animal food. Sources of vegetable food must be found, to supply its place, among the plants richest in albuminous substances. The legumes are the most prominent of these plants. To determine the power of beans to sustain all the functions of life, Dr. Virochiloff performed a series of experiments upon himself, by eating regularly equal quantities of bread and sugar, and adding to them for a certain time meats, for another period peas. The result was, in his own words, that "both the mixtures quite fulfilled the purpose of nutrition, as was proved by the same weight of body being kept up and the forces being maintained in the same state by either food." The meat-mixture was, however, assimilated more readily than that of which the peas formed a part. It is affirmed that men occupied in intellectual work especially need a mixed food; but of this we are not certain, not knowing on what those whose intellectual achievements have been greatest have really lived; and many of them have been very irregular eaters. Taking the history of the human race as a whole, we may observe that races living almost exclusively on meat have been and are the most savage ones. The prehistoric "finds" show that the beginnings