Pasteur himself ever was most kind and helpful to Metchnikoff. During the first years, when his health still allowed it, he used often to come to the laboratory, questioning Metchnikoff on his researches with much interest and always warmly encouraging him. He even attended assiduously his course of lectures on inflammation. After his state of health no longer allowed him to go out, Metchnikoff used to visit him every day, and tried to cheer him by talking to him of current researches. MM. Duclaux and Roux became his closest friends; they were at first brought together by scientific interests and by questions concerning the Institute; but, gradually, personal sympathy grew up between them, binding them by that solid bond which is made up of daily occurrences, inducing respect, confidence, and affection. Moreover, Metchnikoff felt the deepest gratitude towards Pasteur and his collaborators, who had given him the possibility of working in so favourable an atmosphere. From the very first, Pasteur sympathised with the phagocyte theory; the other members of the Institute thought it too biological, almost vitalistic. But when they had made themselves thoroughly cognisant with it, they also adopted it. Thus, having found in the Pasteur Institute not only favourable working conditions but also moral support, Metchnikoff became deeply attached to it, and the interests of "the House" became his. In 1915, on the occasion of Metchnikoff's seventieth anniversary, M. Roux, in a Jubilee speech, gave of him and of his work the following appreciation which describes, better than anything I could say, what his part was in the Pasteur Institute: In Paris as in Petrograd, as in Odessa, you have become a leader of thought, and you have kindled in this Institute a scientific focus which has radiated afar. Your laboratory is more alive than any in the house; workers come to it in crowds. There, the bacteriological events of the day are discussed, interesting preparations examined, ideas sought for that may help an experimenter to solve difficulties in which he has become involved. It is to you that one comes to ask for a control experiment on a newly observed fact, for a criticism of a discovery that does not always survive the test. Moreover, as you read everything, every one comes to you for information, for an account of a newly published memoir which there is no time to read. It is much more convenient than to consult the library and also much safer, for errors of translation and interpretation are avoided. Your erudition is so vast and so accurate that it is made use of by the whole house. How many times have I not availed myself of it? One never fears to take advantage of it, for no scientific question ever finds you indifferent. Your ardour warms the indolent and gives confidence to the sceptical.