The progress made by Kraepelin, Stransky, Wernicke, Bleuler, Ziehen and other modern psychiaters led to renewed interest in pathological research. This was to a considerable extent due to the suggestion of Kraepelin that dementia praecox was autotoxic and endogenous in origin. The neurons were exhaustively studied by Alzheimer and changes in metabolism thoroughly investigated by Folin and many others. To the researches of Nissl and Alzheimer in 1904 we are largely indebted for an accurate knowledge of general paresis. Studies of the cortex in dementia praecox by Alzheimer and many others have been extremely interesting if not conclusive. The introduction of lumbar puncture by Quincke and the studies of the cerebrospinal fluid made by Widal, Plaut, Nonne, Mott and others were of great aid in diagnostic procedure. These have been supplemented by the Wassermann reaction, the colloidal gold test, etc. The isolation of the treponema pallidum in the cortex settled the question of the identity of general paresis and cerebral syphilis for all time. Another line of research responsible in no small measure for the remarkable progress of psychiatry during the last few decades was that instituted by Freud, Jung and others in their studies of psychological mechanisms. It is a rather remarkable fact that it is only in comparatively recent years that a study of the psychological processes of the normal mind has been looked upon as essential to an understanding of the mental reactions involved in the development of a psychoneurosis or psychosis. This is really the basis of Freud's work. Psychiatry may be said to be practically the only branch of medical science in which a study of pathological processes has not been based largely upon physiological and anatomical foundations. Our textbooks for many years have insisted that "insanity" was a disease of the brain but have not given much consideration to a correlation of the physiology with the pathology of that organ. The application of psychological methods to psychiatric research was largely a result of the studies of hysteria by Janet. This was supplemented by the important contribution of Breuer and Freud in 1895 calling attention to their theories in regard to the production of the psychoneuroses by psychic traumas, usually of a sexual nature. Freud's views were outlined more fully in his "Selected Papers on Hysteria," "Three Contributions to the Sexual Theory," and his studies of the "Psychopathology of Everyday Life," etc. The psychological processes of dementia praecox and paranoia were subjected to elaborate studies by Freud, Jung and various other authors.