"This group comprises the essentially benign affective psychoses, mental disorders which fundamentally are marked by emotional oscillations and a tendency to recurrence. Various psychotic trends, delusions, illusions and hallucinations, clouded states, stupor, etc., may be added. To be distinguished are: "The _manic_ reaction with its feeling of well-being (or irascibility), flight of ideas and over-activity. "The _depressive_ reaction with its feeling of mental and physical insufficiency, a despondent, sad or hopeless mood and in severe depressions, retardation and inhibition; in some cases the mood is one of uneasiness and anxiety, accompanied by restlessness. "The _mixed_ reaction, a combination of manic and depressive symptoms. "The _stupor_ reaction with its marked reduction in activity, depression, ideas of death, and often dream-like hallucinations; sometimes mutism, drooling and muscular symptoms suggestive of the catatonic manifestations of dementia praecox, from which, however, these manic-depressive stupors are to be differentiated. "An attack is called _circular_ when, as is often the case, one phase is followed immediately by another phase, e.g., a manic reaction passes over into a depressive reaction or vice versa. "Cases formerly classed as allied to manic-depressive should be placed here rather than in the undiagnosed group. "In the statistical reports the following should be specified:—(a) Manic type; (b) Depressive type; (c) Stuporous type; (d) Mixed type; (e) Circular type; (f) Other types."