Other experimenters have confirmed Dr. Von Pettenkofer’s observations. On October 17 Dr. Emerich made a similar experiment on himself, with like results. Since then, experiments have been made in the Vienna Pathological Institute, with the following results: Six persons partook of the comma bacillus in no mean quantity, and not one of them has had the disease. The six are two doctors, the servant of the Institute, two medical students, and a private gentleman. Professor Stricker treated them all. Two did not feel their health impaired at all; one had headache, was slightly feverish, and could not sleep; two had slight attacks of diarrhœa; and only one was really ill, but recovered at the end of a week. These experiments inspire medical men with serious misgivings as to the theory which considers the comma bacillus as the cause of all cholera. The supremacy of sanitation is the lesson which is being gradually taught by such humane scientific experiments. Dirt in its largest sense, as matter in the wrong place, whether in air, water, food, clothing, habitation, soil, or contact, is undoubtedly a main physical cause of disease. But in all epidemic disease the emotion of fear must be recognised as a most potent predisposing cause. The great fact of mind or emotion is a powerful influence in producing, in preventing, or in curing disease. This psychological side of medicine is only beginning to receive due attention. As the fallacies which arise in animal experimentation from the production of fear, pain, and coma have not yet been fully recognised, so the inevitable influence of mind in modifying physical conditions has never yet been studied scientifically in human medicine. Yet facts exist in unsuspected abundance which need to be collected, verified, tabulated, and their laws of action diligently studied. It is known that even that strong muscle the heart may be ruptured by the agony of intense emotion. At Blackburn the daughter of a woman charged with theft became dumb with horror at her mother’s sudden arrest. Hydrophobia, cholera, and even small-pox, appear to have been caused by fear. The extent to which even the so-called microbes of infectious diseases may be produced by fear acting on idiosyncrasy demands very serious investigation; for as it is now generally conceded that morbid micro-organisms do not exist _ab æterno_, it is essential to know by what unhealthy conditions the micro-organisms, or living particles that always surround us, become disease germs. One of our most distinguished London physicians has full records of the following noteworthy case, which is given, not as scientifically proved, but as indicating a line of research which it is folly to ignore or refuse to investigate.