Page:Popular Science Monthly Volume 5.djvu/785

Rh but, on the contrary, may be produced at a single leap, the author draws the following conclusions:

1. Morphological changes in individual plants are not always by gradual modifications. 2. Variations from specific forms follow the same law. 3. Variations are often sudden, and also of such decided character as to seem generic. 4. These sudden formations perpetuate themselves similarly in all respects to forms springing from gradual modifications. 5. Variations of similar character occur in widely-separated localities. 6. Variations occur in communities of plants simultaneously by conditions affecting nutrition, and perhaps by other causes. From these premises Mr. Meehan argues that new and widely-distinct species may be suddenly evolved from preëxisting forms without the intervention of natural selection, and, of course, without the existence of connecting links.

Many who heard this paper were at first disposed to consider it an attack on Darwinism, its tendency being to lessen the importance of the principle of natural selection. But its discussion showed that such was not the view of those best able to judge; Profs. Morse, Riley, Gill, Gray, and even Mr. Meehan himself, regarded the argument as a contribution to the theory of evolution, while all but the author were of the opinion that it was quite consistent with the principle of natural selection, and, indeed, had already been taken into the account by Mr. Darwin.

Nitrogen of the Soil.—Prof. H. B. Armsby read at the American Association meeting a paper on the "Nitrogen of the Soil," in which, after stating that no plant has the power, so far as we know, of taking its nitrogenous materials directly from the atmosphere, he investigates the sources from which the nitrogen of plants is derived. Nitrogenous organic substances, such as exist "in freshly-manured soils, may yield free nitrogen by decomposition, though the particulars of the process are as yet not fully ascertained. Under some circumstances these organic substances are capable of causing free nitrogen so to enter into combination with them as to increase their nitrogenous contents. This increase has generally been attributed to the formation of nitric acid from free nitrogen by oxidation. The author made a series of experiments on the loss and gain of nitrogen, his method being to allow organic matter containing a known amount of nitrogen to decay, under circumstances allowing measurement of the nitrogen given off or accumulated. The organic matter consisted of dried and sifted barn-yard manure, mixed with one-quarter its weight of dried and pulverized flesh. There were eight experiments in all, four of which were conducted in purified air, and four in purified nitrogen. The quantities and materials used for the two series of experiments were as follows:

The result of the experiments shows a loss of nitrogen in Nos. 1, 3, and 4 of Series I., amounting to 11.11, 6.21, and 13.09 per cent, respectively; and in Nos. 3 and 4, of Series 11., of 1.14 and 1.94 per cent. No. 2, of Series I., shows a gain of 15.22 per cent.; and Nos. 1 and 2, of Series II., a gain of 1.48 and 19.34 per cent, respectively. The author's conclusions are: 1. The loss of free nitrogen during the decomposition of nitrogenous organic matter is generally due to oxidizing action. 2. An increase of combined nitrogen in soil may take place by oxidation of free nitrogen to nitric acid. 3. Some organic substances in the presence of a caustic alkali are able to fix free nitrogen without the agency of oxygen, or the formation of nitric acid.

Tea-Production in Bengal, British India.—In the entire presidency about 800,000 acres are "held for purposes connected with the tea-industry." Of this only about 70,000 acres are occupied with tea-plants in bearing. This portion is subdivided