Page:Popular Science Monthly Volume 56.djvu/748

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POPULAR SCIENCE MONTHLY.

The discovory that the bacteria of the root nodules of leguminous plants possess the power of absorbing the free nitrogen of the atmosphere and rendering it available for the use of the plant was made by Messrs. Hunter and McAlpine, according to Mr. Young, and was taught by them to their students several years before Hellriegel, to whom it is usually ascribed, fell upon it. They found that several well-defined sets of bacteria were concerned in the work of nitrification, and isolated and cultivated the nitrous germ, but could accomplish nothing with the nitric germ till they used old mortar or some lime dressing with it. They also found that lime compounds in the surface soil served a further important use by preventing the soluble silicates from being taken up by the roots of the plant, the lime taking up those salts and forming insoluble silicates which were retained in the soil and did not diffuse into the plant. So a non-silicated stem, or a cellulose stem, was formed, which would bend before the wind without breaking, while the non-silicated straw was much superior in value to the silicated straw. Messrs. Hunter and McAlpine denied that silica in the plant gave strength and solidity to the stem, and pointed out that it rather, like glass, made the straw brittle. They found out, further, that large quantities of carbonic acid were produced in the soil through the operation of the ferments, and found an outlet through the subsoil drains. They made other discoveries which threatened to render it necessary to revise the whole fabric of agricultural science, and were called to account by the institutions in which they were teachers for their heresies. They maintained their position till the opportunity came to them to make tests of their theories on Lord Rosebery's Dalmeny farm. Among the results of the Dalmeny experiments are proof of the value of a dressing of ground lime in proportions not large enough to kill the bacteria, emphasis of the value of potash for every crop, and the discovery of a remedial treatment for the finger-and-toe pest in turnips. "When these experiments were commenced, ground lime for agricultural purposes had never been heard of, whereas now there are at least six lime works where extensive grinding plants are kept hard at work to supply the ever-increasing demand for that substance. Since the principles for the new soil science have been put in successful practice at Dalmeny the scientific authorities, who at first had branded these principles as absurd heresies, have changed their tune," and now the chemical advisor of the Highland Society has declared that he accepts the new doctrines.

 

Plague Antitoxin.—In justifying his belief in the efficacy of the inoculation treatment against the plague, Lord Curzon, the Viceroy of India, said, in a recent address at Poonah: "If I find, as I do find, out of one hundred plague seizures among uninoculated persons, the average number who die is somewhere about seventy to eighty per cent, while, in a corresponding number of seizures among inoculated persons, the proportions are entirely reversed and seventy to eighty per cent, if not more, are saved—and these calculations have been furnished from more than one responsible quarter—I say figures of that kind can not fail to carry conviction; and I altogether fail to see how, in the face of them, it is possible for any one to argue that inoculation is not a wise and necessary precaution." He had been personally visiting the plague hospitals and camps about the city, and had already supported his advocacy of this treatment by having himself and his party inoculated at Simla with the plague antitoxin.

 

Cultivation of India Rubber.—An article in the Bulletin of the Bureau of American Republics represents that there are lands in Mexico and Central America equally adapted to the cultivation of the India-rubber tree with the Brazilian plantations, and having, in addition, a salubrious climate. Formerly dependence for the supply of India rubber was placed in the product of wild trees, but with the increase in the uses for it, and the consequent rise in prices, capital is being invested in this industry, and its profitable cultivation is being largely engaged in. The trees do not flourish at an elevation exceeding five hundred feet above sea level, and low land, moist but not swampy, is the best. Land suitable for planting