and chemists active in these fields have benefited from these lectures and the interchange of ideas during the course. The aim of the Institute was to familiarize young scientists in the field with the current state of the art and to indicate in which areas advances may be expected in the near future. The A.S.I. consisted of two parts: detailed instructional and review lectures over the whole period and some evening sessions where the partici­ pants were offered the opportunity to present their own work and discuss their ideas with senior scientists. Since the Institute took place a few weeks after Prof. Dr. John C. Slater was suddenly taken from our scientific community, it was a great honor for us to dedicate this course, on behalf of the organizing committee, to the late John C. Slater.