1. Bertinshaw, D., Lawler, S. D., Holt, H. A., Kirman, B. H., and Race, R. R. (1950). Ann. Eugen. Camb., 15, 234.
2. Chown, B. (1944). Amer. J. clin. Path., 14, Tech. Sect., 8, 114.
3. Chown, B. and Lewis, M. (1946). Canad. med. Ass. J., 55, 66.
4. Chown, B. and Lewis, M. and Bryce, A. (1948). Ibid., 59, 379.
5. Chown, B. and Lewis, M. and Bryce, A. and Bryce, A. and Peterson, R. F. (1951). In the press.