1. BROADFOOT, K. D., GLOSTER, J., and GREAVES, D. P. (1961). Brit. J. Ophthal., 45, 161.
2. BUCHANAN, W. M., GLOSTER, J., and GREAVES, D. P. (1962). J. Physiol. (Lond.), 162, 2P. RusHTON, W. A. H. (1956). Ibid., 134, 11.
3. CAMPBELL, F. W., HAGINS, W, A,, and BRINDLEY, G. S. (1956). Optica Acta, 1, 183.
4. WEALE, R. A. (1953). J. Physiol. (Lond.), 122, 322.