1. Shaw, E., and Gibbs, R. D., Nature, 190, 463 (1961).
2. Lodge, F., Sci. Progr. Twent. Cent., 49, 497 (1961) and references cited therein.
3. Erdtman, H., Harvey, W. E., and Topliss, J. G., Acta Chem. Scand., 10, 1381 (1956). Erdtman, H., Perspectives in Organic Chemistry, 473 (Intersci. Pub., New York, 1956).
4. Purdy, S. J., and Truter, E. V., Nature, 190, 554 (1961).
5. Waldron, J. D., Gowers, D. S., Chibnall, A. C., and Piper, S. H., Biochem. J., 78, 435 (1961). Martin, J. T., J. Sci. Food Agric., 11, 635 (1960).