This international Symposium on the biology of memory was held in the Biological Research Institute at Tihany, Lake Balaton in September 1969. The meeting covered nearly all biological aspects of recent research on elementary learning and memory storage. This complex approach proved to be fruitful: the lectures, discussions, as well as the the chairmen's con­ cluding remarks reflected the main problems of this most exciting, but rather controversial field of interdisciplinary research. The volume contains the thirty papers read at the Symposium, arranged in a different sequence than they had been presented during the four-day meeting. These changes made by the Editor were necessary in order to follow the logical succession of the different topics, rather than the chron­ ology of the lectures, which was inevitably influenced by the itineraries of some of thc participants from ahroad. Consequently the sequence of the concluding remarks had to be altered, too. The division of the book into six parts according to the different topics is tentative because of the mul­ tiple overlappings. The discussions of the lectures had to be digested, since the presentation of a complete record would have been difficult.