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3. FISHER, J. H. (1903). Ibid., 23, 73.
4. SNELL, A. C. (1927). Trans. Amer. ophthal. Soc., 25, 216.
5. STORY, J. B., and BENSON, A. H. (1883). Trans. ophthal. Soc. U.K., 3, 108.