Gentlemen,—I feel it a great honour to be asked to address your learned Society, and yet it is not without misgiving that I have undertaken the task. I am, indeed, somewhat abashed at the temerity which has led me to discuss Medico-Psychological problems before such masters of the subject as I see before me, but I am in some measure reconciled to the position in which I find myself by the consideration that the kindness which induced my friend, Mr Mould—I presume, with your sanction—-to ask me to address you, will be extended so far as to incline you to overlook my shortcomings. It is also possible that an exchange of ideas between the general physician and the alienist on the great subject of mental disorders may be productive of good to both. For between complete sanity and that degree of mental derangement which the law recognizes as insanity there is a wide border-land of disordered physical functions, in which the opportunities of the general physician for making observations may even be greater than those of the alienist himself, and it is from this border-land chiefly that I have culled the few observations which I propose to present to you to day.