This represents an interesting compilation of essays and articles that had been individually published by the writer at previous times. The first of these appeared in 1922. An attempt is made to explain the genesis of criminal characters on anomalies of physical development, especially anomalies of the cerebrum. Minor anomalies passed through several generations have a tendency to breed degeneracy. The author has examined many criminals and in the majority of instances finds evidence of some endocrine dysfunction. The suggestion is offered that such dysfunction may be materially lessened by the administration of endocrine gland substances. A lengthy discussion of studies in modern biology follows. The author goes further and shows that the will of man is subconscious and man's actions are subordinated to his individual mechanical somatic properties. The application of these studies to the science of criminology is in opposition to the usual "moral metaphysics." It will take