1. Freese, E., Proc. U.S. Nat. Acad. Sci., 45, 622 (1959).
2. Demerec, M., Lahr, E. E., Balbinder, E., Miyake, T., Mack, C., Mackay, D., and Ishidsu, J., Carnegie Inst. Wash. Year Book, 58 (1959).
3. Zamenhof, S., et al., J. Biol. Chem., 219, 165 (1956).
4. Freese, E., J. Mol. Biol., 1, 87 (1959).