Page:Popular Science Monthly Volume 30.djvu/739

Rh was given a whole plant, with root and stem, by a native, and found its odor penetrating enough. The stem is three or four feet high; the leaves are incised like those of other umbelliferous plants. The root is impregnated with the gum, which exudes wherever a cut is made, appearing of a light amber-color, hard consistency, and somewhat crystalline look. The root bears numerous side-roots, and is covered with a brown, scaly skin, crossed with rings. The plant grows in stony ground, blooms in the spring-time, and is propagated from the seeds. The gum is not collected from the roots till the plant is fifteen years old. At that time the stalk is cut off after the plant has blossomed and the seed has ripened. In a day or two afterward there exudes a thick, creamy, whitish juice, that soon becomes brown and hard. In about twelve days the amber-colored gum is taken off. A new cut is then made in the plant, and another "crop" of gum collected; and the operation may be repeated, if the season is favorable, six or eight times in a single summer. But the returns from the later cuttings are inferior to those from the first. A single root may furnish from a half pound to a pound of the gum in a season. Rain spoils the gum, and if it happens to be wet during the time of collecting, the crop for that year will have to be written down a failure. The plant that has been once operated upon is left to itself for ten or twelve years, when it becomes available for another crop.

Brain-Volume and Intelligence.—Dr. Adolph Bloch has published in the "Revue d'Anthropologie" a memoir on the relations existing between intelligence and the volume of the brain in man. He concludes that there is no absolute relation, for very intelligent persons may have a small brain, and individuals of very mediocre capacity a large one. We may also find among some races which are not considered very intelligent a brain or cranial capacity of relatively considerable amplitude. The conditions, moreover, which make the brain to be larger or smaller are manifold. The volume of the encephalus may be related to the size, to the weight of the body, and to the muscular power; and the brain itself may become voluminous in the race and the individual according to the degree of intellectual activity. The most important factor in the degree of the intelligence of the individual is the quality of the cerebral cell; and that is determined by the greater or less impressionability or excitability of that structure regarded as the substratum of intelligence. This impressionability may be native or acquired. In the former case it is the mark of a superior intelligence; in the latter, it may be produced by such sustained labor as every man of genius is compelled to endure. It may also be developed by nervous disease. In a whole race, there are influences, not depending on the individual, but acting upon all that contribute to the perfection of intelligence and the selection of remarkable men. The kind and degree of intelligence are also variable according to races; but in no case can the volume of the brain alone constitute the principal factor of intelligence.

The Protection of Rare Species of Plants.—The Association for the Protection of Plants, at Geneva, Switzerland, Henry Correvon secretary, has issued a circular, setingsetting [sic] forth its objects and inviting horticulturists and collectors to assist it in carrying them out. The circular alludes to the anxiety which naturalists feel lest some rare species may be extinguished through the operations of man; and others which but for the possession of unusual means of defense would be in danger of succumbing at once under an attack of more than ordinary vigor. Some species are approaching the term of their existence. Their end may be hastened by man, although he may perhaps not be able greatly to prolong their lives. Some plants are cultivated in modified forms as choice varieties, while the original stocks are neglected and allowed to die out; some, of foreign origin, live a kind of colonial existence in particular countries, and need care to preserve them there. Some are the objects of vigorous search by amateurs and horticulturists, who often pluck them recklessly without reflecting that the place where they are found may be the only spot in the country where they occur. The Dracocephalum Austriacum and Dictamus fraxinella have nearly disappeared from their native haunts. Plants like the Faradisia