PAUL KARRER, professor of chemistry in the University of Zurich, is one of the world's leading organic chemists. A pupil of Ehrlich, his work, beginning on chemotherapeutic problems, has since ranged over a wide field of organic chemistry. In particular Jie has achieved outstanding success in the study of substances of biological importance, notably in the vitamin field, and his work hasplayed a large part in the spectacular successes of organic chemistry during the last twenty years. Karrer's work on the carotenoid pigments and the structural elucidation of vitamin A has been the basis of our present knowledge of the group, and mention may also be made of his constitutional work on the structure and synthesis of vitamin B2 (riboflavin) and the vitamins E. Notable contributions, too, have been made by him to the chemistry of plant colouring matters of the anthocyanin type, and to our knowledge of the nature and mode of action of variousco-enzymes. His laboratories have for long been a centre of attraction for workers from many countries. The brilliance of his achievements was recognized in 1937 by the award of a Nobel Prize. In addition to furthering chemistry by his research, Karrer has made a notable contribution to teaching through his text-book of organic chemistry, which enjoys a worldwide reputation.