1. Francis, E., U.S. Pub. Health Service, Public Health Rep., 38, 1396 (1923).
2. Snyder, T. L., Penfield, R. A., Engley, jun., F. B., and Creasy, J. C., Proc. Soc. Exp. Biol. Med., 63, 26 (1946).
3. Tamura, J. T., and Fleming, D. E., Abstr. Soc. Amer. Bacteriol., 49th meeting, 37 (1949).
4. Snell, E. E., Strong, F. M., and Peterson, W. H., Biochem. J., 31, 1789 (1937).
5. Mills, R. C., Berthelsen, H., Donaldson, D., and Wilhelm, P. L., Abstr. Soc. Amer. Bacteriol., 49th meeting, 37 (1949).