1. Unpublished observations;ASHTON, N.;Ann. Rev. Med,1957
2. WARD, B., and SERPELL, G. (1953). British Journal of Ophthalmology, 37, 513.
3. WARD, B., and SERPELL, G. (1954). Ibid., 38, 397.
4. BARTLEY, W., DAVIES, R. E., and KREBS, H. A. (1954). Proc. roy. Soc. B., 142, 187.
5. COOK, C., and ASHTON, N. (1955). British Journal of Ophthalmology, 39, 626.