In corroboration of this view, Professor Koch and others state that the minor organisms of tubercular disease do not occur in the tissues of healthy bodies, and that when introduced into the living body their propagation and increase is greatly favored by a low state of the general health. The President held that for the present sanitary procedure was independent of these theories on the germ origin in particular of zymotic disease; but gave the facts as worthy of consideration, as indicating points for the direction of those who aimed at preventing disease. The President dealt with the important subject of isolation in the cases of contagious zymotic diseases, and then, proceeding to discuss the subject of epidemic diseases, said: Notwithstanding the numerous experiments and the great efforts which have been made in recent times to endeavor to trace out the origin of disease, the sanitarian has not yet been able to lift up the veil which conceals the causes connected with the occurrence of epidemic diseases. These diseases come in recurring periods, sometimes at longer, sometimes at shorter intervals. Animals, as well as the human race, are similarly affected by these diseases of periodical recurrence; but why they prevail more in one year than in another we are entirely ignorant. They appear to be subject to certain aerial or climatic conditions. Cholera affords an illustration of this. There is a part of India, low-lying, water-logged, near the mouth of the Ganges, where cholera may be said to be endemic. In certain years, but why we know not, it spreads out of this district, and moves westward over the country; the people are sedentary, and seldom leave home, but the cholera travels on. At last it arrives on the borders of the desert, where there are no people, and no intercourse, no alvine secretions, and no sewers, yet the statistician sitting in Calcutta can tell almost the day on which the epidemic influence will have crossed the desert. But it exercises discrimination in its attacks, It will visit one town or village and leave many others in the vicinity untouched. Similarly it will attack one house and leave another. But it has been generally found that the attacked house or village held out special invitation from its insanitary condition. The same houses or the same localities will be revisited in recurring epidemics, because the conditions remain the same; remove those conditions, and at the next recurrence the locality will escape. At Malta it was found that the same localities and houses which yielded the majority of plague deaths there in 1813 yielded the majority of the deaths in the cholera epidemics of 1839 and 1867, and that in the intervals the same localities yielded the majority of cases of small-pox, fever, and of an anthrax, a very special eruptive epidemic attended by carbuncles. Hence, while we are unable either to account for the cause or to prevent the periodic recurrence of epidemics, the