Dr. Edward Eden, a specialist in lung diseases, has a strong interest in the comparative physiology of lung structure and function in animals. He grew up in England and as a child was always fascinated by birds. This interest has developed and flourished throughout his life. Currently director of the Pulmonary Physiology Laboratory at Mount Sinai Hospitals, Dr. Eden will review the principles of structure of mammalian and avian lungs and the relationship of this to the physiologic functions of ventilation, gas exchange and oxygen supply. Dr. Eden will highlight some variations in structure and physiology as adaptations to oxygen demand in some species of birds.