1. Balls, M., Cancer Res., 22 (in the press).
2. Leone, V., Tumori, 39, 420 (1953).
3. Leone, V., R.C. Ist. lombardo, B, 92, 220 (1957).
4. Schlumberger, H. G., and Lucké, B., Cancer Res., 8, 657 (1948).
5. Lucké, B., and Schlumberger, H. G., Physiol. Rev., 29, 91 (1949).