A careful and elaborate study of a completely developed sadist has been furnished by Lacassagne, Rousset, and Papillon ("L'Affaire Reidal," _Archives d'Anthropologie Criminelle_, Oct.-Nov., 1907). Reidal, a youth of 18, a seminarist, was a congenital sanguinary sadist who killed another youth and was finally sent to an asylum. From the age of 4 he had voluptuous ideas connected with blood and killing, and liked to play at killing with other children. He was of infantile physical development, with a pleasant, childish expression of face, very religious, and hated obscenity and immorality. But the love of blood and murder was an irresistible obsession and its gratification produced immense emotional relief. Sadism generally has been especially studied by Lacassagne, _Vacher l'Eventreur et les Crimes Sadiques_, 1899. Zoösadism, or sadism toward animals, has been dealt with by P. Thomas, "Le Sadisme sur les Animaux," _Archives d'Anthropologie Criminelle_, Sept., 1903. Auto-sadism, or "auto-erotic cruelty," that is to say, injuries inflicted on a person by himself with a sexual motive, has been investigated by G. Bach (_Sexuelle Verrirungen des Menschen und der Nature_, p. 427); this condition seems, however, a form of algolagnia more masochistic than sadistic in character. With regard to the medico-legal aspects, Kiernan ("Responsibility in Active Algophily," _Medicine_, April, 1903) sets forth the reasons in favor of the full and complete responsibility of sadists, and Harold Moyer comes to the same conclusion ("Is Sexual Perversion Insanity?" _Alienist and Neurologist_, May, 1907). See also Thoinot's _Medico-legal Aspects of Moral Offenses_ (edited by Weysse, 1911), ch. xviii. While we are probably justified in considering the sadist as morally not insane in the technical sense, we must remember that he is, for the most part, highly abnormal from the outset. As Gaupp points out (_Sexual-Probleme_, Oct., 1909, p. 797), we cannot measure the influences which create the sadist and we must not therefore attempt to "punish" him, but we are bound to place him in a position where he will not injure society.