and others, performed on a few mice; and, on the other hand, the popular experiments which were performed on a half-million of human beings in London during the cholera epidemics of 1848-'49 and 1853-'54 by the water companies. M. Villemin has gained information of incalculable value concerning the causes and nature of tubercle from his laboratory experiments on other animals than man, and has been followed by others who have developed and extended his discoveries. Professor Gerlach, of Hanover, has in a similar manner studied the transmissibility of tubercle from animals to man by eating their flesh and drinking their milk. The popular experiments, performed by milk-dealers serving their customers, which lead us to suspect that tuberculosis might be transmissible through milk, are performed daily upon thousands of human beings. "The scientific experiments which have made us certain of the fact were conclusive when they amounted to half a dozen. Thus, without making any account of the relative value of human beings and animals, the scientific experiments are vastly more economical than the popular. They have the further advantage of being precise and exact, while the popular experiments very often have in them sources of ambiguity which lessen their usefulness for teaching." The principal problems to be solved in preventive medicine are how, by cross-breeding or otherwise, to convert a short-lived or constitutionally enfeebled stock into a long-lived or vigorous one, which has hardly yet become a practical question; and how to avoid or resist the extensive interferences which shorten life, on which much has been learned by vivisection, and more remains to be learned. Of the investigations in the latter line which have led to results of momentous value are cited the diversified researches of Pasteur and others on germs, and their specific applications to the diseases of domestic animals and man; Drs. Klebs and Tommasi Crudelli's examinations into the intimate cause of marsh-malaria; Dr. Grawitz's studies of the conversion of ordinarily harmless microphytes into agents of deadly infectiveness; Dr. Lister's application of Pasteur's discoveries to the antiseptic treatment of wounds; Professor Semmer and Dr. Krajewski's discovery of inoculation against septæcemia; and Dr. Schüller's contributions to the treatment of tubercular and scrofulous affections, on the basis of their microphytic origin. No work has been performed of more promise to the world than these various contributions to the knowledge of disease, its cure and prevention; and they are contributions which from the nature of the case have come, and could only have come, from the performance of experiments on living animals.
A Dangerous Tendency in Science.—Mr. W. Spottiswoode, in his president's address before the Royal Society, has sounded the note of alarm against an evil that has begun to affect science, and may result in harm if it grows. Research, he suggests, is being drawn into the hurry that characterizes other departments of life in our generation, and the glamour of sensational fame is too apt to blind the eye to the light of the solid honor which is the real and best reward of science. "Apart from other reasons, the difficulty, already great and always rapidly increasing, of ascertaining what is actually new in natural science; the liability at any moment of being anticipated by others, constantly present to the minds of those to whom priority is of serious importance; the desire to achieve something striking, either in principle or in mere illustration—all tend to disturb the even flow of scientific research. And it is, perhaps, not too much to say that an eagerness to outstrip others rather than to advance knowledge, and a struggle for relative rather than absolute progress, are among the most dangerous tendencies peculiar to the period in which we live." Happily, this tendency has not yet become general in science, and Mr. Spottiswoode's calling attention to it may go far toward providing a cure for it.
The Supposed Volcanoes in Central Asia.—The existence of volcanoes in Central Asia was formerly generally recognized on the authority of Humboldt. As the vast regions included in that country have become more accessible to Europeans, many of the supposed volcanoes have been proved to have no real existence, and the investigations of Russian explorers have resulted in showing that what in many