This paper is intended as a contribution to the surgery of those primary tumors which occur in the optic nerve. As long ago as 1901, from the laboratories of the Royal Victoria Hospital, I issued a monograph, with which possibly some of you may be acquainted, dealing more especially with the pathologic aspect of the subject. I now propose to lay before this Section of the American Medical Association the experience which I have acquired since that time in the clinical aspects of these cases and in the operative procedures for their removal. As preliminary to that, however, I shall be obliged to define more clearly the conclusions at which I have arrived on the pathology of these growths. Simultaneously with the arrival of the invitation that I should address this meeting, I encountered a clinical experience which encouraged me to undertake the task, for tumors of the optic nerve