June 17, the examination of a fresh furuncle on the same individual gave the same result, the development of a pure culture of the same organism.

Fifth observation.—­July twenty-first, Dr. Maurice Reynaud informed me that there was a woman at the Lariboisiere hospital with multiple furuncles.  As a matter of fact her back was covered with them, some in active suppuration, others in the ulcerating stage.  I took pus from all of these furuncles that had not opened.  After a few hours, this pus gave an abundant growth in cultures.  The same organism, without admixture, was found.  Blood from the inflamed base of the furuncle remained sterile.

In brief, it appears certain that every furuncle contains an aerobic microscopic parasite, to which is due the local inflammation and the pus formation that follows.

Culture fluids containing the minute organism inoculated under the skin of rabbits and guinea-pigs produce abscesses generally small in size and that promptly heal.  As long as healing is not complete the pus of the abscesses contains the microscopic organism which produced them.  It is therefore living and developing, but its propagation at a distance does not occur.  These cultures of which I speak, when injected in small quantities in the jugular vein of guinea pigs show that the minute organism does not grow in the blood.  The day after the injection they cannot be recovered even in cultures.  I seem to have observed as a general principle, that, provided the blood corpuscles are in good physiological condition it is difficult for aerobic parasites to develop in the blood.  I have always thought that this is to be explained by a kind of struggle between the affinity of the blood corpuscles for oxygen and that belonging to the parasite in cultures.  Whilst the blood corpuscles carry off, that is, take possession of all the oxygen, the life and development of the parasite become extremely difficult or impossible.  It is therefore easily eliminated, digested, if one may use the phrase.  I have seen these facts many times in anthrax and chicken-cholera, diseases both of which are due to the presence of an aerobic parasite.

Blood cultures from the general circulation being always sterile in these experiments, it would seem that under the conditions of the furuncular diathesis, the minute parasite does not exist in the blood.  That it cannot be cultivated for the reason given, and that it is not abundant is evident; but, from the sterility of the cultures reported (five only) it should not be definitely concluded that the little parasite may not, at some time, be taken up by the blood and transplanted from a furuncle when it is developing to another part of the body, where it may be accidentally lodged, may develop and produce a new furuncle.  I am convinced that if, in cases of furuncular diathesis, not merely a few drops but several grams of blood from the general circulation could be placed under cultivation frequent successful