In July, 1961, twenty-nine of the leading scientists in lung disease research met in London under the auspices of the Ciba Foundation and discussed for three days the relationship between pulmonary structure and function. The participants were physiologists, anatomists, pathologists, and physicians. Eighteen formal papers were presented, and most were followed by spirited discussion. Dr. A. A. Liebow presented the first paper, which summarized recent knowledge in pulmonary anatomy. The other formal presentations considered the proprioceptive control of breathing (E. J. M. Campbell), the glomus pulmonale (V. E. Krahl), bronchial gas flow (P. Hugh-Jones), cellular structure and mucus activity in the bronchial tree and alveoli (H. Hayek), the mechanics of respiratory structures (J. Mead), ventilation-perfusion relationships (H. Rahn), pulmonary gas exchange using radioactive gases (J. B. West), physiological and biochemical effects of pulmonary artery occlusion (J. H. Comroe, Jr.), the microscopic structure of the human lung (C. G. Loosli), gas