To a gathering of physicians, each of whom is actively engaged in the treatment of insanity, it would be both impertinent and needless for me to enlarge upon the present-day position of our knowledge of clinical psychiatry. As you are aware, each new discovery in the laboratory of medical science has been seized upon, elaborated, and applied to the treatment of mental diseases or considered in connection with it. Unfortunately the laboratory workers exercise only too fully the ancient prerogative of doctors to differ, and their observations and the results of their researches are thus vitiated, and further research rendered all the more difficult and needful. If the dawn and full daylight of bacteriological science have impressed us with the all-importance to mankind of the infinitely little, may I be pardoned for stating that at the present time the importance of securing more unanimity of opinion amongst its competent research workers is infinitely great.