Page:Popular Science Monthly Volume 36.djvu/443

Rh those of Europe. The arboreous vegetation, the last members of which are commonly birches, pines, and junipers, usually ends at about twelve or thirteen thousand feet above the sea-level, the shrubby growths ascending a thousand feet higher. The Alpine region is thus attained, where, under the influence of the frequent showers that fall upon the mountain-slopes exposed to the south, the open pastures are adorned, during their short summer, with flowers of every hue and in the greatest profusion and luxuriance, including well-known European forms, such as gentian, primula, anemone, ranunculus, and many others. With increased elevation, and as the ranges are less directly exposed to the rain-bearing winds from the south, the climate becomes colder and drier, the vegetation more scanty, the forms fewer; and on reaching the border of Thibet, at an elevation of fourteen or fifteen thousand feet, where the atmospheric conditions are wholly changed, the aspect of the country is that of a desert—treeless and bare, as a rule—and, excepting in the rare neighborhood of water, not one twentieth of the surface is clothed with vegetation, and such bushes as there are seldom rise to a greater height than one or two feet.

Experimental Fields at Rothamstead.—The grass-land experimental field at Rothamstead consists of about seven acres, and is divided into twenty plots. It has probably been laid down in grass for some centuries. It is certain that no fresh seed has been artificially sown within the last fifty years; and there is no record of any having been sown since the grass was first laid down. The experiments were begun in 1856, when the herbage was uniform in character. Each plot has been treated differently. One has had no manure, others have had farm-yard dung, superphosphate of lime, ammonia salts, sulphate of potash, or other chemicals. Sir John Lawes said to a writer in the "Pall Mall Gazette," who visited the farm, that "the result was evident in many ways. On one plot the fertilizers supplied had fed only a single kind of grass, which had covered the whole area, killing out all the rest. On another the grass was hard and wiry, scarcely fit for food; and on yet another the land was little better than a bog. We can not go into technical details as to the results, but these experiments have shown that the food which plants receive, either artificially from the soil, or by the atmosphere, determines their nature as much as in the case of animals. The same thing is seen in the wheat and barley fields. One of the most important of the former is a section upon which the grain has been grown continuously for forty-five years, in one case without manure. The average of the first recorded eighteen years gave 14 bushels per acre, and last year the same quantity was produced, showing that in the soil there is a large reserve amount of fertility." In another part of the field, Sir John Lawes told the writer: "Five years ago we left the upper end of this wheat-field uncropped, allowing the corn to fall when ripe. In three years there was scarcely a single ear of corn left; those which I could find were short in the stalk, and with perhaps a single grain. Now there is not one. This shows that food-products are almost entirely artificial, and that in a few years the land would be a perfect wilderness, if uncultivated. But I myself was surprised at the rapidity with which the wheat disappeared." This was explained thus: "The weeds were stronger, and killed out the artificial grain. Weeds are hardy, and it is really 'the survival of the fittest' or the hardiest. The same thing I can show you in the turnip-field, where the unmanured plot is almost barren, the plants having scarcely in any case formed a bulb. It is the starch we want as food. Cultivation and fertilization give that starch."

Palm-Oil.—Palm-oil is the product of the fruit of the oil-palm tree of Guinea. The fruit grows in clusters on top of the tree, which is about thirty feet high, and resembles a chestnut. The oil is extracted by boiling the pulpy and fibrous mass around the central nut, and is used in making soap and candles. The fruits are harvested in April. The oil of Arachis, which is equally important in commerce, is from the nut of the Arachis (peanut), thousands of tons of which are sent to Europe every year to be made up into "olive-oil." It is the fruit of an annual creeping plant (Arachis hypogea), and ripens in July and August. Oils of inferior quality are made into soap. Another underground nut (Voandzeia subterranea)