1. Ponder, E., Ann. N.Y. Acad. Sci., 48, 600 (1947).
2. Pauling, L., Itano, M. A., Singer, S. J., and Wells, I. C., Science, 110, 543 (1949).
3. Pauling, L., Itano, M. A., Wells, I. C., Schroeder, W. A., Kay, L. M., Singer, S. J., and Corey, R. B., Science, 111, 459 (1950).
4. Sherman, I. J., Bull. Johns Hopkins Hosp., 67, 309 (1940).
5. Swann, M. M., and Mitchison, J. M., J. Exp. Biol. (in the press).