U.S. zoologist and physiologist whose work in marine biology contributed to the early study of bioluminescence. From 1911 until his retirement in 1956 he taught at Princeton University, becoming H.F. Osborn professor of biology in 1933. His research, primarily in cellular physiology, centred on the biochemical mechanism of light production in animals. In the early 1900s he used extracts made from dried luminous Cypridina, a marine crustacean, to illustrate the substrate oxidation reaction often responsible for bioluminescence. His books include The Nature of Animal Light (1920), Living Light (1940), and Bioluminescence (1952).