1. BILLINGHAM, R. E., and MEDAWAR, P. B. (1952). J. exp. Biol., 29, 454.
2. DRAHEIM, J., MCPHERSON, S. D., EVANS, V. J., and EARLE, W. R. (1957). Amer. J. Ophthal., 44, 6/10, no. 4 [Oct.], pt 2, p. 182.
3. FARRANT, J. (1965). Nature (Lond.), 205, 1284.
4. LEIGH, A. G., and RIDGE, J. W. (1957). Trans. ophthal. Soc. U.K., 77, 367.
5. LOVELOCK, J. E. (1953a). Biochim. biophys. Acta, 10, 414.