The knowledge of the composition of the structure of the normal eye is directly related to the interpretation of the physiology and pathology of the eye. The recent tendency in the chemistry of the eye has been to search for abnormalities in the aqueous and vitreous humors and in the lens, and to disregard the remaining ocular structure. But it must be remembered that the eye functions as an entire organ and that its tissues are physiologically interdependent. The chemistry of the sclera, which is the most important ocular supporting tissue, has been incompletely investigated. Michel and Wagner1 found 34.49 per cent solids and 0.867 per cent ash in the sclera, and Mörner2 reported 0.84 per cent ash and calculated that the sclera contained about 13 per cent mucoid and 87 per cent collagen. Since the time of these reports, however, biologic chemistry has made remarkable progress in