The peroxide of hydrogen which I used was a 3.2% solution, yielding fifteen times its volume of oxygen; but this strength reduced to about 1.5%, corresponding to about eight volumes of oxygen, by adding the fresh culture containing the microbe upon which I was experimenting. I have also experimented upon old cultures loaded with a large number of the spores of the bacillus anthracis. In all cases my experiments were made with a few cubic centimetres of the culture in sterilized test-tubes, in order to obtain accurate results. The destructive action of peroxide of hydrogen, even diluted in the above proportions, is almost instantaneous. After a contact of a few minutes, I have tried to cultivate the microbes which were submitted to the peroxide, but unsuccessfully, owing to the fact that the germs had been completely destroyed. My next experiments were made on the hydrophobic virus in the following manner: I mixed with sterilized water a small quantity of the medulla that had been taken from a rabbit that had died of hydrophobia, and to this mixture added a small quantity of peroxide of hydrogen. Abundant effervescence took place, and, as soon as it ceased, having previously trephined a rabbit, I injected a large dose of the mixture under the dura mater. Slight effervescence immediately took place, and lasted a few moments, but the animal was not more disturbed than when an injection of the ordinary virus is given. This rabbit is still alive, two months after the inoculation. A second rabbit was inoculated with the same hydrophobic virus, which had not been submitted to the action of the peroxide, and this animal died at the expiration of the eleventh day, with the symptoms of hydrophobia. I am now experimenting in the same manner upon the bacillus tuberculosis, and if I am not deceived in my expectation, I will be able to impart to the profession some interesting results. It is worthy of notice that water charged, under pressure, with fifteen times its volume of pure oxygen has not the antiseptic properties of peroxide of hydrogen. This is due to the fact that when the peroxide is decomposed nascent oxygen separates in that most active and potent of its conditions next to the condition, or allotropic form, known as "ozone." Therefore, it is not illogical to conclude that ozone is the active element of peroxide of hydrogen. Although peroxide of hydrogen decomposes rapidly in the presence of organic substances, I have observed that its decomposition is checked to some extent by the addition of a sufficient quantity of glycerin; such a mixture, however, cannot be kept for a long time, owing to the slow but constant formation of secondary products, having irritating properties. Before concluding, I wish to call attention to a new oxygenated compound, or rather ozonized compound, which has been recently discovered, and called "glycozone," by Mr. Marchand.