Those who visited an ambulance ward during the war of 1870, especially those who were medical students, have preserved such a recollection of the sight that they do not, even now, care to speak about it. It was perpetual agony, the wounds of all the patients were suppurating, a horrible fetor pervaded the place, and infectious septicæmia was everywhere. “Pus seemed to germinate everywhere,” said a student of that time (M. Landouzy, who became a professor at the Faculty of Medicine), “as if it had been sown by the surgeon.” M. Landouzy also recalled the words of M. Denonvilliers, a surgeon of the Charité Hospital, whom he calls “a splendid operator ... a virtuoso, and a dilettante in the art of operating,” who said to his pupils: “When an amputation seems necessary, think ten times about it, for too often, when we decide upon an operation, we sign the patient’s death-warrant.” Another surgeon, who must have been profoundly discouraged in spite of his youthful energy, M. Verneuil, exclaimed: “There were no longer any precise indications, any rational provisions; nothing was successful, neither abstention, conservation, restricted or radical mutilation, early or postponed extraction of the bullets, dressings rare or frequent, emollient or excitant, dry or moist, with or without drainage; we tried everything in vain!” During the siege of Paris, in the Grand Hôtel, which had been turned into an ambulance, Nélaton, in despair at the sight of the death of almost every patient who had been operated on, declared that he who should conquer purulent infection would deserve a golden statue. It was only at the end of the war that it occurred to Alphonse Guérin--(who to his intense irritation was so often confounded with another surgeon, his namesake and opponent, Jules Guérin)--that “the cause of purulent infection may perhaps be due to the germs or ferments discovered by Pasteur to exist in the air.” Alphonse Guérin saw, in malarial fever, emanations of putrefied vegetable matter, and, in purulent infection, animal emanations, septic, and capable of causing death.