"This bond has become so much part of myself that my first impulse is always to act in the way he would have approved. I even feel the need to share with others what I received from him. I do not know whether it will be given to me to solve certain problems posed by him, but I have the conviction that his spirit, in its purity, will be preserved among us. He will ever live in those who worked by his side, and in those who will come to work in his laboratory. It cannot be otherwise." Metchnikoff on his part never remained indifferent to his pupils. His solicitude towards them was warm, sometimes paternal, always ready and active. Many of his pupils remained his friends and collaborators for years afterwards. His fiery and exclusive temperament, however, made him take up a very different attitude in exceptional cases, when he found himself in front of one who persisted in a path which Metchnikoff himself considered the wrong path, or before an action which he thought disloyal or work done without conscience. Then he became beside himself, and positively dangerous to those who had exposed themselves to the paroxysm of his indignation. Fortunately such cases were rare; as a general rule, the atmosphere of his laboratory was impregnated with scientific spirit and ardour; all forces in it converged towards the same goal, being bound together by a community of aspirations and activity of which he was the soul. * * * * * The first period of his life in France was taken up by the strengthening and development of the phagocyte theory and by an eager struggle in its defence. He displayed in it his full energy as a scientist and a fighter, and this was perhaps the most agitated, the most tense period of his life. When at last his theory was securely established and began to be accepted, he continued his researches with the same passionate ardour but in an atmosphere of peace. It was joy and bliss to him to be able to work apart from other preoccupations, and the years of his life between fifty and sixty were the happiest he ever had. The state of his soul and his ideas had considerably evolved in the course of years; the great moral and physical sensitiveness which had so often made him miserable in his youth had decreased and he had become much less impulsive. Unpleasant sensations no longer caused him so much suffering; he could bear the mewing of a cat or the barking of a dog; personal vexations no longer made him take such a horror of life as to wish to be rid of it: he now merely tried to conquer them.