We propose in this paper to deal with the subject of the effects produced upon mental disorders by intercurrent bodily disease. The theme is an old one, but we feel justified in calling attention to it afresh, partly because it is at present prominently before the minds of many alienists, partly since those who have concerned themselves with it—in this country, at any rate—have principally been content with the mere indication of the facts observed. The pathology of the subject, the domain of experimental research and scientific speculation, remains comparatively unexplored. Our literary survey leads us to conclude that but little has been written upon this subject of late years.