All those who have worked with insulin will have been impressed by the great freeing of behaviour that the patients exhibit. It is seen in the hypoglycæmic state, before coma sets in, and as the patient returns to consciousness after interruption of the coma. The degree of this freeing varies directly with the prognosis. In this uninhibited state the anatomy, the very bones of the personality, can be studied, and the physician's observations should be able to establish the main outlines of the pathology of the total personality—the psycho-pathology.