1. W. Karrer,ibid., p. 551.
2. W. Karrer,ibid., p. 554.
3. L. D. Scheel, “Biochemistry of Some Foodbone Microbial Toxins,” ed. by R, I. Mateles and G.N. Wogan, The M. I. T. Press, Cambridge, Massachussetts and London, 1966, p. 109.
4. F. M. Dean, “Naturally occurring oxygen ring compounds,” Butterwoths, London, 1963, p. 176.
5. Private communication from Dr. E. Ritchie.