There is a much greater danger than that of atmospheric germs, that of the contagium germ, of which the surgeon’s hands; sponges and tools are the receptacle, if minute and infinite precautions are not taken against it. Such precautions were not even thought of in those days; charpie, odious charpie, was left lying about on hospital and ambulance tables, in contact with dirty vessels. It had, therefore, been sufficient to institute careful washing of the wounds, and especially to reduce the frequency of dressings, and so diminish the chances of infection to obtain--thanks to a reform inspired by Pasteur’s labours--this precious and unexpected remedy to fatalities subsequent to operations. In 1873, Alphonse Guérin, now a surgeon at the Hôtel Dieu, submitted to Pasteur all the facts which had taken place at the hospital St. Louis where surgery was more “active,” he said, than at the Hôtel Dieu; he asked him to come and see his cotton-wool dressings, and Pasteur gladly hastened to accept the invitation. It was with much pleasure that Pasteur entered upon this new period of visits to hospitals and practical discussions with his colleagues of the Académie de Médecine. His joy at the thought that he had been the means of awakening in other minds ideas likely to lead to the good of humanity was increased by the following letter from Lister, dated from Edinburgh, February 13, 1874, which is here reproduced in the original-- “My dear Sir--allow me to beg your acceptance of a pamphlet, which I send by the same post, containing an account of some investigations into the subject which you have done so much to elucidate, the germ theory of fermentative changes. I flatter myself that you may read with some interest what I have written on the organism which you were the first to describe in your _Mémoire sur la fermentation appelée lactique_. “I do not know whether the records of British _Surgery_ ever meet your eye. If so, you will have seen from time to time notices of the antiseptic system of treatment, which I have been labouring for the last nine years to bring to perfection. “Allow me to take this opportunity to tender you my most cordial thanks for having, by your brilliant researches, demonstrated to me the truth of the germ theory of putrefaction, and thus furnished me with the principle upon which alone the antiseptic system can be carried out. Should you at any time visit Edinburgh, it would, I believe, give you sincere gratification to see at our hospital how largely mankind is being benefited by your labours. “I need hardly add that it would afford me the highest gratification to show you how greatly surgery is indebted to you. “Forgive the freedom with which a common love of science inspires me, and “Believe me, with profound respect, “Yours very sincerely,