In the concerted attack on the schizophrenias, biological theories are being increasingly tested pari passu with psychological ones. While Kraepelin has already theorized about autointoxication as the basis of schizophrenia and Jung has speculated on the “toxin-x” as its cause, actual research of a biological nature has had to wait for its pioneers and its tools. The history of the main streams of current research go back a little over 40 years. The reproduction of schizophrenic target symptoms became possible as a result of (1) Pavlov’s work on experimental anxiety states in animals through conditioned frustration, (2) the production of miniature rhinencephalic lesions based on the pioneering works of Papez, Bard, and Bucky and Klüver, and (3) the discovery of bulbocapnine, mescal, LSD25, and a host of other psychotomimetic drugs, the research possibilities of which were outlined by the insightful suggestions of Louis Lewin,