The hereditary conditions underlying the two degenerative processes—opticptic atrophy and retinitis pigmentosa—are similar to a certain extent. Leber's disease is not common; many ophthalmologists of wide experience have never with certainty seen a case. No microscopic examination has been made in this condition so far as I know. The primary pathologic manifestation of Leber's disease is in the form of an axial rather than a peripheral degeneration. The papillomacular bundle is vulnerable; and it is very sensitive to various environmental poisons, bacteriologic and chemical—quite apart from the effect of an hereditary taint. In the reports of institutions, it is not always possible to separate this type of optic nerve involvement so as to yield data of scientific value; and unless the family history is accurate, the factor of heredity is uncertain. Its time of onset is usually about the twentieth year, although authentic cases beginning at 5 and 6