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Page:Popular Science Monthly Volume 49.djvu/441

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423
FRAGMENTS OF SCIENCE.

chemical analysis was first made which indicated that the ingot from which the shaft had been forged was cast too hot; that the carbon was very unevenly distributed, the center of the shaft containing fifty per cent more than the portion near the circumference; and, finally, that the content of sulphur and phosphorus was three times greater in the core than at the circumference, and excessive in all parts of the mass. But the most important and instructive results were obtained in the microscopic examination of sections. Micrometallography is a comparatively new science, which, however, already promises to be of great practical value to the metal-worker. The microscopical examination showed a bad structural arrangement of the iron and steel "cells," especially in the core. The, phosphorus, as phosphide, was distributed pretty generally, and the cohesion between crystals rich in phosphide is very faulty. The center of the shaft was riddled with sulphide of iron, and was little tougher than good gray pig iron. "It is almost certain that a number of sulphide flaws of the interior gradually worked outward, along the crystalline junctions of the fairly tough metal outside, until under a vibratory shock of unusual force the whole mass ruptured."

 

The Tsetse Fly.—The few travelers whose lot has led them through the lowlands of equatorial Africa have most of them reported the tsetse fly (Glossina sp.) as one of the most formidable impediments in the way of colonization or even exploration of these regions. Wild animals and human beings suffer only temporary irritation from its attacks, but domestic animals entering the fly districts are seized in the course of a few days with fever and wasting, and almost invariably die. The tsetse is a dipter, having a pale yellow abdomen and gray, striped thorax. It is rather larger than the house fly. The mouth parts form a powerful piercing beak. From an account of a report on the tsetse-fly disease, by Surgeon-Major David Bruce, published in Nature, we learn that there has at last been an attempt made to study the fly and its disease in a thorough and scientific manner. As far back as 1870 a Mr. St. Vincent Erskine endeavored to show that the disease was due solely to change of grass and climate. Since then several other travelers have stated their belief that the fly was not injurious, or, at any rate, that the ill effects of its bite were much exaggerated. At last the Natal Government has authorized Mr. Bruce to thoroughly investigate the tsetse-fly disease, and his paper is the outcome of the first three months' work. The results so far attained seem to indicate not the action of a specific virus, as was originally supposed, but the transmission by the tsetse fly of a bacterium or its products. The investigation is proceeding along somewhat the same lines which Dr. P. Manson is following in endeavoring to trace the malaria plasmodium through the mosquito. A similar relationship was traced some years ago between Texas fever, a disease of cattle, in which certain parasitic bodies were found in the red blood corpuscles, and the cattle ticks (Ixodidæ). Among the new facts brought to light by Dr. Bruce's work, one of considerable importance is the specific action which arsenic seems to have on the disease; its administration causes a reduction in temperature, a maintenance of the normal number of red blood cells, and a disappearance of the hæmatozoa from the blood.

 

Serum Therapy and Blood Brotherhood.—The very ancient practice of the transfusion of blood from one person to another, as a means of cementing friendship, seems, in the light of the modern serum treatment of disease, to have been something more than a purely sentimental operation. In a recent letter to Nature, T. L. Patterson discusses the probable value of such inoculations. He thinks it very probable that a European inoculated with the blood or serum of a native would be better able to resist the climatic changes to which he is subjected in tropical countries. "In other words, would blood inoculation not set up in his system those changes necessary to adapt him to the climate, and render him immune to the diseases which are the result of the climate? The suggestion is based on the assumption that the native is more healthy in his own climate than any foreigner can be, and that blood inoculation would acclimatize the latter at once. The advantages to be derived from such a system are obvious. At present, in central Africa, many missionaries and pioneers are annually sacrificed to the cli-