First observation.—­On June second, a puncture was made at the base of the small cone of pus at the apex of a furuncle on the nape of the neck.  The fluid obtained was at once sowed in the presence of pure air—­of course with the precautions necessary to exclude any foreign germs, either at the moment of puncture, at the moment of sowing in the culture fluid, or during the stay in the oven, which was kept at the constant temperature of about 35 degrees C, The next day, the culture fluid had become cloudy and contained a single organism, consisting of small spherical points arranged in pairs, sometimes in fours, but often in irregular masses.  Two fluids were preferred in these experiments—­chicken and yeast bouillon.  According as one or the other was used, appearances varied a little.  These should be described.  With the yeast water, the pairs of minute granules are distributed throughout the liquid, which is uniformly clouded.  But with the chicken bouillon, the granules are collected in little masses which line the walls and bottom of the flasks while the body of the fluid remains clear, unless it be shaken:  in this case it becomes uniformly clouded by the breaking up of the small masses from the walls of the flasks.

Second observation.—­On the tenth of June a new furuncle made its appearance on the right thigh of the same person.  Pus could not yet be seen under the skin, but this was already thickened and red over a surface the size of a franc.  The inflamed part was washed with alcohol, and dried with blotting paper passed through the flame of an alcohol lamp.  A puncture at the thickened portion enabled us to secure a small amount of lymph mixed with blood, which was sowed at the same time as some blood taken from the finger of the hand.  The following days, the blood from the finger remained absolutely sterile:  but that obtained from the center of the forming furuncle gave an abundant growth of the same small organism as before.

Third observation.—­The fourteenth of June, a new furuncle appeared on the neck of the same person.  The same examination, the same result, that is to say the development of the microscopic organism previously described and complete sterility of the blood of the general circulation, taken this time at the base of the furuncle outside of the inflamed area.

At the time of making these observations I spoke of them to Dr. Maurice Reynaud, who was good enough to send me a patient who had had furuncles for more than three months.  On June thirteenth I made cultures of the pus from a furuncle of this man.  The next day there was a general cloudiness of the culture fluids, consisting entirely of the preceding parasite, and of this alone.

Fourth observation.—­June fourteenth, the same individual showed me a newly forming furuncle in the left axilla:  there was wide-spread thickening and redness of the skin, but no pus was yet apparent.  An incision at the center of the thickening showed a small quantity of pus mixed with blood.  Sowing, rapid growth for twenty-four hours and the appearance of the same organism.  Blood from the arm at a distance from the furuncle remained completely sterile.