1. Barnes, J., Brady, M. J., & James, E. M., Am. J. Dis. Child., Chicago, 1930, XXXIX, 45.
2. Cathcart, E. P., Murray, A. M. T., & Shanks, M., Med. Res. Council, Spec. Rep. Series, No. 151, London, 1931.
3. De Sanctis, A. G., & Craig, J. D., J. Am. Med. Ass., Chicago, 1930, XCIV, 1284.
4. Frazier, C. N., & Hu, C. K., Arch. Int. Med., Chicago, 1931, XLVIII, 507.
5. Kirkpatrick, quoted by Wright, R. E., Brit. J. Ophth., London, 1922, VI, 164.