Karrer, << KAHR ur, >> Paul (1889-1971), a Swiss chemist, shared the 1937 Nobel Prize for chemistry with British chemist Sir Walter Haworth. Karrer became famous for his researches on vitamins, especially vitamin A and the carotenes. He also worked on vitamins E and K. His research led him to study vegetable dyestuffs, and he became an authority on flavones, the parent substances of many yellow plant pigments. He was born in Moscow.