1. ARKIN.-Amer. Ji. Path., July, 1930. BENNETT and LEvINE.-Jl. Amer. Med. Assoc., Vol. CLXXVII, June, 1929.
2. BOCK.-Zeitschr. f. Augenheilk., Vol. LXIX, June, 1929. Ibid., Vol. LXXVIII., July, 1932.
3. GAYNON and ASHBURY-Amer;CHRISTELLER. Arch. f. Verd., Vol. XXXVII, 1926. EVANS. Proc. Roy;Soc. Med,1929
4. GRUBER.-Arch. f. Path. Anat., Vol. CCLVIII, p. 441, 1925. HANSSEN and KNACK.-Ki%n. Monatsbt.f Augenheilk., Vol. LIX, p. 263, 1917. HELPERN and TRUBEK.-Arch. Path., Vol. XV, January, 1933.
5. HERRESCHWAND.-Klin. Monatsbl. f. Augenheilk., October-November, 1929. KING.-Trans. Ophthal. Soc. U.K., 1935. KRAHULIK, ROSENTHAL and LOUGHLIN.-Amer. Ji. Med. Soc., September, 1935. KUSSMAUL and MAIER.-Deutsches Augenheilk.f. Klin. Med., Vol. I, p. 484, 1866.