Élie Metchnikoff, now Professor at the Pasteur Institute in Paris, is one of the most distinguished of the disciples who left all else to follow Pasteur. He was born on the third (16) May, 1845, in a village of the Government of Kharkoff (Little Russia). He was educated at the Gymnasium and the University of Kharkoff, passing through the Faculty of Science. From 1864 to 1870 he worked at Zoology at Giessen, Göttingen and Munich, successively under three well-known zoologists, Leuckhart, Henle and Von Siebold, and was then appointed Professor of Zoology and Comparative Anatomy at Odessa. He made expeditions to Madeira, Teneriffe and the Kalmuck Steppes in connection with his zoological researches. In 1882, in consequence of administrative difficulties, arising as part of the troubles that followed the murder of the Tzar, Alexander II., he resigned the Professorship and became Director of the municipal Bacteriological Laboratory. In 1888 he went to the Pasteur Institute, and has remained there since that time. The earlier part of Metchnikoff’s career was devoted to Zoology, and chiefly to investigation of the embryological history of the lower invertebrates, and the sequence of his discoveries should afford food for reflection to those Baconian economists who are unwilling to shelter any tree of knowledge that does not give immediate promise of marketable fruit. The labour of many years spent in minute tracing of the development of insects, echinoderms, worms and jellyfish, would appear sufficiently unprofitable to those who give a scanty support to Botany as the provider of drugs, who tolerate Chemistry because it has supplied aniline dyes, and who patronise the physical sciences from a lively sense of the convenience of telephones and telegraphs. And yet from these remote, inhuman interests, Metchnikoff, without intellectual transition, passed directly to results affecting vitally the human race, and became one of the high priests of Bacteriology and a guardian of the Pandora’s box of modern times.