1. Glaser, G. H., and Kennard, D. W., Nature, 193, 1110 (1952).
2. Whitteridge, D., in Handbook of Physiology, Sect., 1, edit. by Field, J., Magoun, N. W., and Hall, V. E., 2, 1094 (Amer. Physiol. Soc., Washington, 1960).
3. Brindley, G. S., and Merton, P. A., J. Physiol., 153, 127 (1960).
4. Kennard, D. W., and Smyth, G. L. (in course of publication).