Written a hundred years ago by Bernard H. Spilsbury, Pathologist to St Mary’s Hospital, London. To any medical man may come an urgent summons to a case of sudden and unexpected death. Sometimes he is unable to certify the cause, even after post-mortem. It is in such circumstances that my assistance as a pathologist is invited. It is customary, for medico-legal purposes, to regard death as the result of failure in function of one of the three systems: nervous, circulatory, and respiratory. This the first of three articles presents some circulatory causes of death.