1. Aykroyd, W. R., J. Hyg., Camb., 1930, XXX, 357.
2. Balmain, A. R., see Burton, H. G. 3. Barenberg, L. H., & Lewis, J. M., J. Am. Med. Ass., Chicago, 1932, XCVIII, 199. 3a. Bennett, T. I., Hunter, D., & Vaughan, J. M., Quart. J. Med., Oxford, 1932, N.S., I, 603.
3. Quoted by Blegvad, 0
4. Blegvad, O., Am. J. Ophth., St. Louis, 1924, VII, 89.
5. Quoted by Blegvad, 0;Blessig, 1866