Some forty years ago, Dr. Bruce Thomson, the first resident surgeon to this prison, contributed to the medical journals a series of observations upon over 5,000 prisoners. He dealt chiefly with the more obvious physical defects which, to his thinking, supported the theory of the existence of the instinctive criminal, and though his observations were somewhat generalised, he was rightly regarded as a pioneer in the science of criminal anthropology. He also drew attention to the prevalence of weak-mindedness among juvenile prisoners, and stated that as much as 12 per cent. of all prisoners required special observation soon after admission because of mental defect. There is little doubt that in his time the old method that consigned all forms of disordered conduct to prison still persisted, and many changes have since taken place that would tend to diminish his percentage. Prison discipline is still, in spite of its mildness, largely credited with bringing into prominence many symptoms that are put down to mental defect. It would be reasonable to look for a considerable reduction in the numbers of weak-minded persons in prisons during a period when prison administration can conscientiously take to its credit the fruits of a progressive spirit that is not, however, readily granted to it by many whose reforming enthusiasm takes no thought of the spade-work that has preceded their own awakening. The psychological point of view is prominent in the most recent methods of dealing with the criminal. Preventive detention for the habitual, probation for the first offender, Borstal training for the juvenile delinquent, etc., all recognise the mental aspect of the offender as fully as any system that can be evolved by the mental pathologist. That the mental abnormality of the habitual major offender is a more complex affair in its origin and treatment than is insanity will, I am sure, be amply verified by the future experience of the preventive detention institutions, where grave disorder can only result if the treatment views too much in this light of irresponsibility the vicious tendencies of the inmates. From whatever point of view we look upon the habitual and professional criminal, it is certain that many of this type may be safely left to the law which is rightly concerned with the protection of the public, and continually progresses in an endeavour to fit the punishment to the individual.