The so-called experimental psychoses have been in the focus of increased interest recently, as a result of the discovery of new hallucinogenic or psychotic agents and of the fact that the problems can be approached more closely even in the borderline fields of pathopsychological research (biochemistry, electrophysiology, etc.) owing to advance in technique. Thus, it appears that Kraepelin's dream of producing so-called miniature psychoses by the administration of substances foreign to the body will come true after all.