This Symposium, held August 4-10, 1985 on the campus of Oregon State University in Corvallis, is the sixth of a series of international symposia concerned with broad aspects of the fixation of nitrogen gas by biological and chemical means. The first symposium of this series was held in Pullman, Washington (1974), the second in Salamanca, Spain (1976), the third in Madison, Wisconsin (1978), the fourth in Canberra, Australia (1980) and the fifth in Noordwij~erhout, The Netherlands (1983). Prior to the organization of these symposia, small groups of usually no more than 10 or 12 of the now "old...