When Paul Bert, his favourite pupil, M. d’Arsonval, his curator, M. Dastre, a former pupil, and M. Armand Moreau, his friend, came to see him, he said to them in short, enigmatical sentences, with no comment or experimental demonstration, that he had done some good work during the vacation. “Pasteur will have to look out.... Pasteur has only seen one side of the question.... I make alcohol without cells.... There is no life without air....” Bernard’s and Pasteur’s seats at the Academy of Sciences were next to each other, and they usually enjoyed interchanging ideas. Claude Bernard had come to the November and December sittings, but, with a reticence to which he had not accustomed Pasteur, he had made no allusion to his October experiments. In January, 1878, he became seriously ill; in his conversations with M. d’Arsonval, who was affectionately nursing him, Claude Bernard talked of his next lecture at the Museum, and said that he would discuss his ideas with Pasteur before handling the subject of fermentations. At the end of January M. d’Arsonval alluded to these incomplete revelations. “It is all in my head,” said Claude Bernard, “but I am too tired to explain it to you.” He made the same weary answer two or three days before his death. When he succumbed, on February 10, 1878, Paul Bert, M. d’Arsonval and M. Dastre thought it their duty to ascertain whether their master had left any notes relative to the work which embodied his last thoughts. M. d’Arsonval, after a few days’ search, discovered some notes, carefully hidden in a cabinet in Claude Bernard’s bedroom; they were all dated from the 1st to the 20th of October, 1877; of November and December there was no record. Had he then not continued his experiments during that period? Paul Bert thought that these notes did not represent a work, not even a sketch, but a sort of programme. “It was all condensed into a series of masterly conclusions,” said Paul Bert, “which evidenced certitude, but there were no means of discussing through which channel that certitude had come to his prudent and powerful mind.” What should be done with those notes? Claude Bernard’s three followers decided to publish them. “We must,” said Paul Bert, “while telling the conditions under which the manuscript was found, give it its character of incomplete notes, of confidences made to itself by a great mind seeking its way, and marking its road indiscriminately with facts and with hypotheses in order to arrive at that feeling of certainty which, in the mind of a man of genius, often precedes proof.” M. Berthelot, to whom the manuscript was brought, presented these notes to the readers of the _Revue Scientifique_. He pointed to their character, too abbreviated to conclude with a rigorous demonstration, but he explained that several friends and pupils of Claude Bernard had “thought that there would be some interest for Science in preserving the trace of the last subjects of thought, however