He finds the senile psychoses occurring usually between the ages of sixty-five and eighty, although they occasionally appear before sixty. Seven and sixty-seven hundredths per cent of his cases were between sixty and sixty-five years of age; ten per cent between sixty-five and seventy; thirty-five per cent between seventy and seventy-five; 27.8 per cent between seventy-five and eighty; 22.2 per cent between eighty and eighty-five; 10.5 per cent between eighty-five and ninety; and 2.78 per cent were over ninety years of age. Of 183 cases studied, twenty-three per cent were cases of presbyophrenia; sixty-three per cent of simple deterioration; eight per cent of arteriosclerotic origin; and the remainder, of delusional forms. More than half of the cases of presbyophrenia occurred in persons over seventy-five. The paranoid and arteriosclerotic forms occurred in younger individuals. In the alcoholic cases the Korsakow complex was common. The analysis of presenile psychoses made by Kraepelin is, to say the least, exceedingly interesting. Such clear-cut differentiations as he describes are, however, not always possible or necessary. Very few other writers have gone into the question so exhaustively, nor is his classification of these conditions generally accepted. Bleuler[161] in 1918 in discussing the presenile psychoses quotes Kraepelin's classification and also refers to Gaupp's anxious depressive forms. Under the senile deteriorations he describes "dementia senilis" and presbyophrenia. He also calls attention to the fact that Binswanger spoke of a "pre-senile dementia" occurring between the fortieth and fiftieth years of age and characterized by an emotional dulness and a diminished capacity for work. Bleuler speaks of the affective disturbances in advanced years as senile mania and melancholia, which he says may recover, the former frequently, the latter more rarely. The American Psychiatric Association has only attempted to cover the principal groupings of the characteristic senile forms. The differentiation of these conditions as suggested in the statistical manual is as follows:— "A well defined type of psychosis which as a rule develops gradually and is characterized by the following symptoms: Impairment of retention (forgetfulness) and general failure of memory more marked for recent experiences; defects in orientation and a general reduction of mental capacity; the attention, concentration and thinking processes are interfered with; there is self-centering of interests, often irritability and stubborn opposition; a tendency to reminiscences and fabrications. Accompanying this deterioration there may occur paranoid trends, depressions, confused states, etc. Certain clinical types should therefore be specified, but these often overlap: