1. Maas, J. W., Science, 137, 621 (1962).
2. Maas, J. W., Nature, 197, 255 (1963).
3. Sudak, H. S., and Maas, J. W. (in the press).
4. Broadhurst, P. L., J. Animal Behaviour, 9, 129 (1960).
5. Bogdanski, D. F., Pletscher, A., Brodie, B. B., and Udenfriend, S., J. Pharmacol., 117, 82 (1956).