Among the many important advances which have taken place within recent years in the science of medicine, none have surpassed in value or in extent those affecting the nervous system. One of the principal points which these have established, no matter from what direction the subject has been approached, is the recognition of the essential unity of the sciences of neurology and psychiatry. In the domain of psychological medicine, the researches of Freud and Jung on psychopathology and their theories of the subconscious and its manifestations have provided a common meeting-ground; the investigations of Campbell on the cell lamination of the cerebral cortex, and later of Shaw Bolton, have aimed at the elaboration of a scheme of cerebral function based on clinico-histo-pathological proof; the studies of Elliot Smith on the comparative anatomy of the brain and the development of the cerebral cortex peculiar to the mammalia have demonstrated some of the factors which have contributed to the attainment of man's distinctive mental aptitudes, and eventually made possible the emergence of the human intellectual abilities culminating in the development of speech, and the attainment of intellectual pre-eminence within the human family; equally important is the recognition of the integrative action of the nervous system by Sherrington, and his views on the importance of the simple muscle-nerve preparation in explaining the processes involved in cerebral association and the significance of excitation, inhibition and the latent period; and still more recently we have the investigations and publications of Schafer on the influence of the endocrine glands on the nervous system, and of Mott on the relationship of the reproductive and endocrine glands to mental disease, and the light which this has shown on the ætiology of dementia præcox.