Page:Popular Science Monthly Volume 37.djvu/834

814 had died from hydrophobia, and to reduce the germs through numerous generations by a system of modifying treatment until they have lost, in some degree, their fatal virulence, while at the same time they may have retained a protective activity within the limits of safety.

In the warfare with the pathogenic microbes the idea of employing certain species as our allies, and opposing them against the very dangerous ones, is brilliant, and there are many facts encouraging the belief that the kingdom of the microbes may be further divided against itself, through the natural voracity of its numerous clans. Surely any tactics and every means, agressiveaggressive [sic] and defensive, must be made available against an enemy so insidious and so formidable.



N his Lectures on Chemical Philosophy, J. B. Dumas has taken notice of the "singular contrast which is to be remarked among ancient peoples between the nourishing condition of industrial chemistry and the entire absence of theoretical chemistry." Empiricism, commanded by the necessities of material life, had, in fact, to precede the disinterested speculations of the reasoning powers. In this way the Phoenicians and Egyptians made discoveries of great significance in the arts of metallurgy, glass-working, and dyeing, without being guided by any scientific light. They interpreted them in a mystical sense, conformable to their religious conceptions of nature. Whatever we may think of their theories, we can not forget the positive bases of them; for the rational science of our century has been derived from their observations, winnowed by the ages. The facts have resisted the assaults of time, while the magic, the theurgic doctrines, found to be sterile, have gradually disappeared to give place at last to the fruitful idea of natural laws. It was a curious metamorphosis, in which astrology, alchemy, and the old medicine predicating the virtues of stones and talismans, mark the transition from the ancient to the modern mind.

It is with great interest that we follow with M. Berthelot the evolution that has thus taken place in chemistry from the ancient Orientals to the Greeks, and from them to us; for it is associated with the development of philosophical ideas, consequently with the history of the human mind. From the time when alchemy 