A Symposium on the Use of Isotopes in Biology and Medicine.by Hans T. Clarke; Harold C. Urey; Glenn T. Seaborg; Paul C. Aebersold; Alfred O. Nier; Charles D. Coryell; Martin D. Kamen; Donald B. Melville; David B. Sprinson; Harland G. Wood; Konrad Bloch; David M. Greenberg; I. L. Chaikoff; Joseph G. Hamilton; Byron E. Hall; Saul Hertz; William F. Bale; James J. Nickson; Farrington Daniels