It being established that stupors occur as a temporary form of insanity[12] psychiatry is faced at once with the problem of describing these conditions accurately in order to ascertain their nosological position. To this end we first examined typical cases of deep stupor and found that the clinical picture is made up of the following symptoms: In the foreground stands _poverty of affect_. The patients are almost unbelievably apathetic, giving no evidence by speech or action of interest in themselves or their environment, unmoved even by painful stimuli. Their faces are wooden masks; their voices as colorless when words are uttered. In some cases sudden mood reactions break through at rare intervals. The second cardinal symptom is _inactivity_. As a rule there is a complete cessation of both spontaneous and reactive movements and speech. So profound may this inhibition be that swallowing and blinking of the eyes are often absent. The trouble is not a paralysis, however, for reflexes without psychic components are unaffected. Possibly related to the inactivity is the preservation of artificial positions which is called _catalepsy_, a fairly frequent phenomenon. A tendency opposite to the inactivity is seen in _negativism_. This perversity is present in all gradations from outbursts of anger with blows and vituperation to sullen, or even emotionless, muscular rigidity. This last occurs most often when the patient is approached but may be seen when observations are made at a distance. Frequently _wetting_ and _soiling_ are due to negativism, when the patient has been led to the toilet but relaxes the sphincters so soon as he leaves it. A constant feature is a _thinking disorder_. On recovery memory is largely a blank even for striking experiences during the psychosis and, when accessible during the stupor to any questioning, a failure of intellectual functions is apparent. An _ideational content_ may be gathered while the stupor is incubating, during interruptions, or from the recollections of recovered patients. Its peculiarity is a preoccupation with the theme of death, which is not merely a dominant topic but, often, an exclusive interest. Probably to be related to this is a tendency, present in some cases, to sudden suicidal impulses, that are as apparently planless and unexpected as the conduct of many catatonics. Finally the disease is prone to exhibit certain _physical_ peculiarities. A low fever is common and so are skin and circulatory anomalies. A loss of weight is the rule, and menstruation is almost always suppressed.