1. Mather, K., J. Genet., 45, 215 (1943).
2. McGuire, D. C., and Rick, C. M., Hilgardia, 23, 101 (1954).
3. Lewis, D., VIIIth Botanical Cong. (Paris, 1954).
4. Baur, E., Z.I.A.V., 63, 251 (1932). Hackbarth, J., Michaelis, P., and Scheller, G., Z.I.A.V., 80, 1 (1942).