1. Heath, J. C., Daniel, M. R., Dingle, J. T., and Webb, M., Nature, 193, 593 (1962).
2. Haddow, A., Dukes, C. E., and Mitchley, B. C. V., British Empire Cancer Campaign, Thirty-ninth Ann. Rep., Part 2, 74 (1961).
3. Dukes, C. E., et al. (personal communiaction).
4. Gilman, J. P. W., Cancer Res., 22 (ii), 158 (1962).