1. Alvord, E. C., and M. F. G. Fuortes: J. of Physiol. 122, 302 (1953).
2. Benson, A. J., and A. A. Jefferson: J. of Physiol. 118 (1952).
3. Bernhard, C. G.: Acta physiol. scand. (Stockh.) 14, supp. 47 (1947).
4. Bremer, F., V. Bonnet et J. Moldaver: Ard. int. Physiol. 52, 1 (1942).
5. Brock, L. G., J. C. Eccles and W. Rall: Proc. Roy. Soc. 138 B (1951).