The essential feature of Knauer's study was an analysis of post-rheumatic stupors. He describes these as clouded or dream states "not different from physiological sleep and the ordinary artificial narcoses." In them he sees a disturbance of apprehension, an interference with intellectual processes, a retention defect, and a loss of the power of attention. Catalepsy was found to be present in the majority of his cases. The loss of affect was described as being more complete than in manic-depressive psychoses. He speaks of the mood as sad, depressed, anxious, but above all, changeable. Generally speaking this group of psychoses due to somatic disease is one which requires further study. We have comparatively little statistical information on the subject as yet. The differentiation of these conditions as outlined in the Association's statistical manual is as follows:— "Under this heading are brought together those mental disorders which appear to depend directly upon some physical disturbance or somatic disease not already provided for in the foregoing groups. "In the types designated below under (a) to (e) inclusive, we have essentially deliria or states of confusion arising during the course of an infectious disease or in association with a condition of exhaustion or a toxaemia. The mental disturbance is apparently the result of interference with brain nutrition or the unfavorable action of certain deleterious substances, poisons or toxins, on the central nervous system. The clinical pictures met with are extremely varied. The delirium may be marked by severe motor excitement and incoherence of utterance, or by multiform hallucinations with deep confusion or a dazed, bewildered condition; epileptiform attacks, catatonic-like symptoms, stupor, etc., may occur. In classifying these psychoses a difficult problem arises in many cases if attempts are made to distinguish between infection and exhaustion as etiological factors. For statistical reports the following differentiations should be made: "Under (a) 'Delirium with infectious diseases' place the _initial deliria_ which develop during the prodromal or incubation period or before the febrile stage as in some cases of typhoid, small-pox, malaria, etc.; the _febrile deliria_ which seem to bear a definite relation to the rise in temperature; the _post-febrile deliria_ of the period of defervescence including the so-called 'collapse delirium.'