I do not know what the definition of a scientific paper may be. One person to whom I put such a question, replied that it was essential that it should contain some original work or observations. If this be true, I am afraid that I cannot rightly use the term “paper” in respect of what I am going to say this evening. What I have to say will be in the nature of a review of the subject which I hope to illustrate by a series of cases which have come under my notice. I have chosen cerebral arteriography, rather, cerebral angiography, as a subject, because, although a certain amount of work has been done in this field in England, very little has been heard of it. Very much less has been done in this country than has been done abroad, and I feel that if it can be brought into the open, it may stimulate interest in the subject, and it might become a more recognised radiographic procedure. Cases of cerebral tumour are, admittedly, not common, not so common, for example, as neoplasm of the intestine or lungs, but t...