upon health, and of the physical relations of clothing. In short, this new domain of knowledge opened itself to him on all sides. The conviction had grown up in Germany that the care a people takes for its public health may be regarded as an index of its advance in civilization. This care, he taught, concerns not only the healing of diseases, but even more the guarding against them; by the side of the care for the sick should stand a regard for the preservation of health, which should avail itself of the most recent results of science, and should be exercised by the state as one of its most pressing duties. That these views so made their way in Bavaria that professorships of hygiene, of which he was assigned to that in the University of Munich, were established in the high-schools of that kingdom, was mainly due to Pettenkofer; and the interest in hygienic matters, which was minifestedin other ways, was excited chiefly by his motion.
Hygiene of course acquired an increased importance during epidemics, when disease threatened not individuals only, but whole cities and countries. With this category we enter upon the region which Pettenkofer has made the objective point of his activity. The investigations which he published on the nature and spread of the cholera enjoy an authority that is hardly limited by geographical boundaries. Here, indeed, Science has to contend with many unknown factors, and we should contradict the views of our active investigator himself if we should assume to speak of conclusive results. Nearly all in the present theories is provisory; the most varied points of view are opposed one to another; but, notwithstanding this, the beginnings that have been made, and the few fixed points that have been verified with respect to the questions, are a priceless gain. Hardly any other kind of affliction, observes Dr. Stieler, has been in the past so surrounded with superstitions as that of great epidemics. Thousands of persons were murdered in the middle ages on charges of poisoning wells; and, even after this kind of barbarism had disappeared, the terror remained which every danger excites, before which we stand ignorant and defenseless. We have now entered an age of correct discernment; intelligent investigation has taken the place of superstitious fear, and has neutralized its grievous effects by seeking and finding out natural causes. The ghostly element which seemed peculiar to these diseases has been destroyed, for it is no longer able, after the fashion of ghosts, to evade every attack, but has been made accessible and tangible, like every other enemy. Dr. Pettenkofer has had a great part in bringing about the revolution that has taken place, by taking hold of the ghosts, as it were, and compelling them to stand and receive his attacks; and, instead of resigning himself to their supposed machinations, he has taken the chief and leading part in contending against them. His researches have established, however much we may still contend respecting the ultimate origin of cholera, that three conditions appertain
