defects are much more frequent in mentally defective children, and that these defects react in further crip¬ pling the child's mental development.Our study of the eye in the mentally defective child was undertaken with a twofold purpose :1. From studies made in 1907 by Clark and Tyson"• into the nature of the eye changes found in dementia praecox it was shown that a fairly constant eye syndrome was present in that mental disorder, embracing, among other signs, a mild grade of optic nerve degeneration, which was thought to be of autotoxic origin. In the numerous discussions of the paper held before various societies on the occurrence of the optic nerve changes in dementia pragcox, it was thought that the syndrome was due more to a strong tendency to neural degeneration in the precocious dements than to a particular autotoxin, and that careful examinations into the allied states of