As there appears to be no doubt regarding the cause of this change, the importance of the fact can hardly be exaggerated. THE PHYSIOLOGICAL THEORY OF FERMENTATION BY LOUIS PASTEUR TRANSLATED BY F. FAULKNER AND D. C. ROBB AND REVISED THE GERM THEORY AND ITS APPLICATIONS TO MEDICINE AND SURGERY BY MM. PASTEUR, JOURBERT, AND CHAMBERLAND TRANSLATED BY H. C. ERNST, M. D. PROFESSOR OF BACTERIOLOGY IN THE HARVARD MEDICAL SCHOOL ON THE EXTENSION OF THE GERM THEORY TO THE ETIOLOGY OF CERTAIN COMMON DISEASES BY LOUIS PASTEUR TRANSLATED BY H. C. ERNST, M. D. INTRODUCTORY NOTE Louis Pasteur was born at Dole, Jura, France, December 27, 1822, and died near Saint-Cloud, September 28, 1895. His interest in science, and especially in chemistry, developed early, and by the time he was twenty-six he was professor of the physical sciences at Dijon. The most important academic positions held by him later were those as professor of chemistry at Strasburg, 1849; dean of the Faculty of Sciences at Lille, 1854; science director of the Ecole Normale Superieure, Paris, 1857; professor of geology, physics, and chemistry at the Ecole des Beaux Arts; Professor of chemistry at the Sorbonne, 1867. After 1875 he carried on his researches at the Pasteur Institute. He was a member of the Institute, and received many honors from learned societies at home and abroad. In respect of the number and importance, practical as well as scientific, of his discoveries, Pasteur has hardly a rival in the history of science. He may be regarded as the founder of modern stereo-chemistry; and his discovery that living organisms are the cause of fermentation is the basis of the whole modern germ- theory of disease and of the antiseptic method of treatment. His investigations of the diseases of beer and wine; of pebrine, a disease affecting silk-worms; of anthrax, and of fowl cholera, were of immense commercial importance and led to conclusions which have revolutionised physiology, pathology, and therapeutics. By his studies in the culture of bacteria of attenuated virulence he extended widely the practise of inoculation with a milder form of various diseases, with a view to producing immunity. The following papers present some of the most important of his contributions, and exemplify his extraordinary powers of lucid exposition and argument. TO THE MEMORY OF MY FATHER FORMERLY A SOLDIER UNDER THE FIRST EMPIRE CHEVALIER OF THE LEGION OF HONOR The longer I live, the better I understand the kindness of thy heart and the high quality of thy mind. The efforts which I have devoted to these Studies, as well as those which preceded them, are the fruit of thy counsel and example. Desiring to honor these filial remembrances, I dedicate this work to thy memory. L. PASTEUR.