Agenda papers; colloquium programme; copy of Evans's 'Introduction: anaerobic and aerobic environments', published in Biochem. Soc. Trans. 4 (1976), 452-455; correspondence arising at the Biochemical Society Meeting, Bangor, 8-9 April 1976. Evans chaired and introduced the colloquium on Microbial Catabolism: its Role in the Carbon Cycle and Significance for Environmental Problems. 1976