Upon being imprisoned they are unable to adjust themselves to the strict régime, find difficulty in acquainting themselves with the prison regulations and in consequence have to be frequently disciplined. As a result they begin to misinterpret things in the environment and see in these disciplinary measures nothing but persecution on the part of the prison officials. They become suspicious, seclusive, introspective, spend sleepless nights, until suddenly, in the stillness of night, they perceive isolated phonemes. This strengthens their suspicions. They refuse food, become apprehensive, the hallucinations reach a more definite character, until finally they manifest a well-marked persecutory delirium, or may fall into a semi-delirious stuporous state, show numerous catatonic symptoms, become destructive and untidy, and in general present a picture very similar to true catatonia. Removal to the hospital ward frequently serves to put a stop to the process at once, and often before reaching the hospital for the insane they show no traces of the acute mental disorder. The foregoing are types of degenerative psychoses met with in imprisonment, and there can be no question that the prison milieu is the etiologic factor here. To speak here of a progressive disorder to which imprisonment only gives a characteristic coloring is entirely erroneous. A psychosis which is definitely brought on by a certain environment and which is corrected as soon as the environment is changed, must be looked upon as the product of that environment. That the degenerative soil which permits of the development of these disorders cannot be looked upon as a basic disorder, something like dementia præcox, is likewise unquestionable. These individuals have always shown the same traits of character; it is these very same anomalies which brought them in their childhood days in conflict with the school authorities, which later made them inmates of reformatories, and which finally were at the bottom of their habitual criminality. Finally, the total absence of progression to more or less definite end-results excludes the possibility of an organically determined progressive disorder. A psychosis which develops in imprisonment and progresses irrespective of the change of milieu is not a prison psychosis in the sense that this term is here used. The following cases are illustrative of the type under discussion. CASE I.--A. F., aged 31 years; admitted to the Government Hospital for the Insane April 7, 1911. Father alcoholic; died of cancer of liver and stomach. Mother died of tuberculosis. One brother has been confined in the Gowanda State Hospital for the Insane for past five or six years; has always been an excessive alcoholic. One sister, aged 42, has tuberculosis. One of her children died of tuberculosis of the bones. Another sister is hyper-religious and eccentric.