Kraepelin first established the importance of involution melancholia as a form of depression warranting separate consideration. The anxiety psychoses occurring late in life have since been made the subject of exhaustive study by various observers. It was discovered that many of the mental disturbances of the aged could be attributed directly to arteriosclerosis alone. Korsakow's syndrome has been found to be as frequently due to senility as it is to alcoholism. Some of our more modern works on psychiatry have included very elaborate chapters on purely "presenile" conditions. Kraepelin[158] in his last edition devotes twenty pages to a review of this subject. He divides the presenile psychoses into melancholia, anxieties, late katatonia, depressive delusional conditions, anxious delusional types terminating in advanced deterioration, depressive states with deterioration, excitements and paranoid forms. The development of Kraepelin's conception of melancholia has been fully discussed in another chapter. He speaks also of the occasional occurrence of anxious conditions in late life with excitements or an exalted mood with grandiose ideas or even paranoid manifestations. These may present a catatonic picture with more or less inaccessibility, stereotypies, peculiar attitudes and movements, absurd resistance, impulsiveness, desultoriness and disconnected speech. Our knowledge as to the exact causation and nature of katatonia still being far from complete, he knows of no reason why a process of that kind should not be recognized as one of the presenile conditions. Thalbitzer suggested the name, depressive delusional insanity (depressiven Wahnsinn), for the conditions exhibiting numerous delusions and active hallucinations with an emotional reaction "determined by the course of the disease." Rehm also described a similar form associated with arteriosclerotic changes and characterized by hallucinations of hearing, together with mannerisms and sterotypies.