Ten years ago Mr. Jonathan Hutchinson said that the description of a fresh diathesis was almost as easy as the discovery of a new nerve centre or the revelation of a new bacterium. Yet no new diathesis, so far as I know, has since then become generally recognized in our special branch of medicine. To-day the neurotic diathesis stands as god-mother to a large family of diseases, and little has been done to differentiate their ætiology, or to trace their genealogy. On the contrary there seems to be a tendency to exaggerate the importance of environment in the ætiology of many of the diseases of the nervous system, and to ignore the hereditary factor. Especially is this the case with general paralysis. Excepting the writings of a few, a course of reading on the ætiology of general paralysis would incline one to believe that there is no evil under the sun—from syphilis to the cessation of lactation—that may not sufficiently account for the onset of that disease. It seems almost as if the observers had first tried to find an acknowledged raison d'être, and, failing in that, had adduced as “cause” anything in the recent history of the patient at all out of the common, or which had ranked as important in the estimation of his friends.