1. Stock, C. C., Amer. J. Med., 8, 658 (1950); Reilly, H. C., Stock, C. C., Buckley, S. M., and Clarke, D. A., Cancer Res., 13, 684 (1953).
2. Ehrlich, J., Anderson, L. E., Coffey, G. L., Hillegas, A. B., Knudsen, M. P., Koepsell, H. J., Kohberger, D. L., and Oyaas, J. E., Nature (see following communication).
3. Bartz, Q. R., Elder, C. C., Frohardt, R. P., Fusari, S. A., Haskell, T. H., Johannessen, D. W., and Ryder, A., Nature (see following communication).