Abstract
Previous studies from this laboratory have shown that loading with large doses of certain amino-acids and Marsilid produced marked behavioural change in some chronic schizophrenic patients (Pollin, Cardon and Kety, 1961). Methionine and tryptophane produced qualitatively different effects and there was no overlap between marked methionine and tryptophane reactors. The changes with tryptophane were characterized by mood elevation and increased involvement with the environment and extra-version, in several instances to a dramatic degree.