As to the frequency of stupor no figures are available, for the simple reason that the diagnosis in large clinics has not been made with sufficient accuracy to justify any statistics. Most of these cases are usually called catatonia, depression, allied to manic-depressive insanity or allied to dementia præcox. The majority of the stupors reported in this book were in women, but this is merely the result of chance, since it has been easier in the Psychiatric Institute to study functional psychoses in the female division, while the male ward has been reserved largely for organic psychoses. The majority of the patients seem to be between 15 and 25 years of age, so that it is, presumably, a reaction of youthful years. In our experience most cases occur among the lower classes, which agrees with the opinion of Wilmanns who found this tendency among prisoners. This gives a brief description of the deep stupor. But even our typical cases did not present this picture during the entire psychosis. They showed phases when, superficially viewed, they were not in stupor but suffered from the above symptoms as tendencies rather than states. There are also many psychoses where complete stupor is never developed. This gives us our justification for speaking of the _stupor reaction_, which consists of these symptoms (or most of them) no matter in how slight a degree they may be present. The analogy to mania and hypomania is compelling. The latter is merely a dilution of the former. Both are forms of the manic reaction. We consequently regard stupor and partial stupor as different degrees of the same psychotic process which we term the stupor reaction. To understand it the symptoms should be separately analyzed and then correlated.