Since the announcement by Cabot1 that post-mortem findings reveal a high percentage of incorrect clinical diagnoses, the question as to the reason is important. In many institutions special attention has been devoted to the problem, and in the city of New York it was made the subject of a municipal report.2 Recently, in London, a well-known graduate school invited thirty-four specialists to speak on common mistakes encountered in their particular fields. In a review of these lectures, Abrahams3 has presented an outline and analysis of the causes of error. It was, of course, surprising to find that the field of medicine could be divided into thirty-four specialties. A few decades ago such a series of lectures could include but five or six topics. To-day the chest is divided into the lungs and the heart, and, says Abrahams, “even the cardiac specialist exhibited a marked tendency to dichotomy, for a struggle between displaying his experiences as a clinical diagnostician and his skill as a mechanical cardiologist was manifest.”…