In previous communications1 we noted the constancy with which rosettes occur in the eyes of human embryos when large doses of x-rays were applied to the abdomen during the second month of pregnancy. The embryos studied varied in age from 3½ to 7 months. In a fetus that had managed to survive the effects of irradiation until 7 months, besides the conversion of large portions of the retina to rosettes and poorly differentiated tissue there were failure of fusion of the layers of the optic stalk, which appeared to have attempted to differentiate into retina, and, in addition, retardation of the development of the anterior part of the eye, so that the ciliary processes and iris were exceedingly rudimentary. The effects were, then, a curious mixture of stimulation or proliferation of the posterior segment and inhibition or retardation of growth in the anterior segment of the globe. In two