The older extensive literature on this subject, although very interesting from an historical standpoint, offers very little that is of scientific value, and it is only within recent years that a more rational approach to this problem has been attempted. It is easily conceivable that this branch of mental medicine must have shared the fortunes of psychiatry in general in its various phases of evolution, so that in the history of the prison psychoses are reflected the various views which in their day have dominated psychiatry. At present it is the school of degeneracy of Magnan and Moebius which is especially concerned with this problem. Briefly stated, the exponents of this subject belong in a general way to either of the following two schools. The one maintains that the mental disorders occurring in prison differ in no way from those met with in freedom and that imprisonment at most but lends to them a peculiar common coloring which in itself, however, is not of essential importance. The other school takes a directly opposite view. The followers of the latter maintain that the mental disorders which they are wont to term "prison psychoses" are products of predisposition plus external factors. They differ from the true endogenous psychoses in that they are purely psychogenetic in character, and that their highly colored and extremely variable symptomatology is nothing more than a reactive manifestation of a particularly predisposed psyche to definite environmental conditions. According to them we are not dealing here with mental disorders whose origin, course, and termination are independent of the crime and imprisonment, as is the case in the ordinary well-known forms of functional and organic disorders developing in prison, but with psychotic manifestations which bear the most intimate relation to some definite situation, and which are characteristically colored and shaped by the prison milieu.