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556 soda, to which M. Dumas invited the attention of physiologists a year ago; the acetate of potassa, and others. Hitherto the physiological virtues of active principles have been studied only with respect to the higher order of animals: M. Dumas pointed out the great interest there would be in examining the influence they exert over the lower organisms charged with the elaboration of ferments, and over ferments themselves. Such researches not only contribute to a better knowledge of the mechanism itself according to which these principles affect the system of vital phenomena, but they also gain the most useful indications for the healing art. Indeed, beginning with the moment at which M. Dumas and other chemists made known the result of their examinations on this subject, coincident also in time with the experiments of M. Davaine on septicæmia, a vast number of attempts were entered upon, in hospitals and in laboratories, to discover to what extent these anti-fermenting substances hinder morbid fermentations. These attempts are still proceeding; we cannot foretell their success, but we are authorized even now to say that they will not be barren of advantage to the healing art. In this, as in all other departments of scientific activity, we see abstract studies result in useful discoveries.

As a general statement of the subject, all this immense work of fermentations, putrefactions, and corruptions of organic matter, is effected in the world by a small number of species of microscopic cells and filaments, by fungi and spores of the lowest order, of which the germs fill our atmosphere. This is one of the most certain acquisitions of modern science, one of the most important from the point of view of natural philosophy, one of the most productive for those arts that are concerned in improving the condition of mankind. We may now regard it as firmly established; but let us not forget that its establishment has cost two centuries of investigations and labors. Leuwenhoek, in the middle of the seventeenth century, was the first to reveal the microscopic world of the air, and to conjecture its momentous functions. What severe toil, what struggles and tedious trials, since the observations of the Dutch micrograph, to the time of the experimental studies of our contemporary and compatriot, M. Pasteur!



HE Birds-of-Paradise are a small, but renowned family. They received their name from the idea, entertained at one time, that they inhabited the region of the Mosaic paradise. They live in a small locality in Australasia, including Papua or New Guinea, and a few adjacent islands. They are not easily tamed and kept confined; and few have been brought alive from their native locality. Mr. Beale 