This modern era may be said to have been ushered in by the preliminary studies made of general paresis by Haslam in 1798. These were followed by the researches of Bayle, Delaye and finally Calmeil, which definitely established the integrity of that disease as a clinical entity. Even then its specific origin was only a matter of conjecture. When Esmarch and Jessen suggested that general paresis was a syphilitic disease in 1857, their views were rejected by men as prominent as Charcot and Déjerine. Although paranoia is a term which has appeared in the literature of medicine for centuries, it has only had the significance now attached to it since the latter part of the nineteenth century. Its description was foreshadowed perhaps by the monomania of Esquirol and Pritchard and the partial insanity of Rush and others. Heinroth, Griesinger, Magnan, Lasègue, Régis, Falret, Mendel, Krafft-Ebing, Herz, Snell, Werner, Schüle, Ziehen, Kraepelin and many other well-known psychiatrists have played a part in the evolution of paranoia which only definitely displaced the wahnsinn, verrüchtheit, and various other designations of the earlier writers, in the neighborhood of 1890. Paranoia is a term which has only been infrequently used since the general acceptance of Kraepelin's paranoid forms of dementia praecox. Its territory has been still further invaded by paraphrenia, the fate of which, however, is somewhat uncertain as yet. The forerunners of the psychopathic personalities were the moral insanity of Pritchard, the insanity of degeneracy of Morel, Magnan, Régis, Lombroso, etc., and the "demifous et demiresponsables" of Grasset, Trélat and others. The introduction of the "constitutional inferiority" idea into the psychiatry of this country was directly attributable to Adolf Meyer following the work of Koch in Germany. After the elaborate study of alcoholism made by Magnus Huss in 1852 the psychoses due to that condition were described by Bonhöffer, Magnan, Korsakow, Kraepelin and various other writers. The psychoneuroses represent the developments of Brachet, who wrote on hysteria in 1847, Briquet, Oppenheim, Lasègue, Möbius, Charcot, Janet, Babinski, Beard, Kraepelin and many others. To Meyer again we are indebted for the first exhaustive study and classification of the traumatic psychoses. The description of amentia by Meynert in 1881 was of considerable significance. The first comprehensive study of mental disorders associated with the use of cocaine was made by Erlenmeyer in 1886. The same writer was responsible for the first elaborate investigation of morphinism in the year following. Circular insanity was described by Falret in 1851 and again as "folie à double forme" by Baillarger in 1854. Hecker was responsible for an event of great importance in the history of psychiatry when he published his description of hebephrenia in 1871. Kahlbaum in his "Katatonia" made a contribution which was destined to influence the future of medicine in 1874.