Atypical features in stupor have to do mainly with interruptions, interludes as it were, of elation, anxiety or perplexity. These are explicable as awakenings from the nothingness of stupor into imaginations such as characterize the other manic-depressive psychoses. When such tendencies are present, the co-existence of the stupor process may tone down the emotional response or prevent its complete repression so that insufficient or dissociated affects appear. A combination of the stupor tendency to apathy with the mood of another reaction is probably the only combination of affects to be met with in psychiatry. The stupor reaction, then, is a simple regression, with a limitation of energy, emotion and ideational content, the last being confined to notions of death. All functional psychoses are regressions. How do the others differ from this? We need only answer this question in so far as it concerns the clinical states resembling benign stupors. Stupors occur frequently in catatonic dementia præcox. In this disease there is a regression of interest to primitive fantastic thoughts, and with this a perversion of energy and emotion. This corrupts the purity of the stupor picture so that inconsistencies, such as empty giggling, atypical delusions and scattered speech, occur. Other impurities are to be found in the frequent orientation of the dementia præcox stupor patient which is discovered to be astonishingly good, or in free speech associated with apathy and inactivity. Such symptoms usually appear quite early and should enable one to make a positive diagnosis within a short time after patient comes under observation. As a matter of fact, in many if not most cases there is a slow onset characterized by the pathognomonic symptoms of dementia præcox before the actual stupor sets in. Other psychoses superficially resembling stupor are the perplexity and absorbed manic (manic stupor) states. We have reason to believe that both these conditions are essentially the result of absorption in kaleidoscopic ideas. Their appearance is that of inactivity and indifference to the outside world, just as a dreamer seems placid and apathetic. But these reactions are not without emotion which may sometimes be obvious, and the richness of the mental content is sooner or later manifest. Finally, from a practical standpoint, an important peculiarity of benign stupor is the tendency for response to stimulation in amelioration of the process. Close attention to these patients is advisable, therefore, not merely for the sake of their physical health, but also because any attention tends to keep them mentally alive or revive their waning energy. Visits of relations often initiate recovery in a striking way. From occurrences such as these, psychiatrists should gain hints for valuable therapeutic experiments.