Ventilation I N Two Species O F Lizards during Rest and Activity

A b s t r a c t 4 . Oxygen consumption. ventilation frequency and tidal volume were measured simultaneously in two lizards, Varanus pouldii and Sauronrabts hispidus, during rest and maximal activity. 2. Ventilation frequency m d tidal volume are almost identical in these species. The grcater oxygen consumption during activity of Varanus results from a grcater oxygen extraction from ventilated air. 3. Incrcased oxygen consumption during activity results from incremcnrs in tidal volume; ventilation frequency remains constant. 4. The t h e m 1 and weight dependence of ventilatory variables in reptiles is analyzed. 5. The capacity for oxygen extraction by saurian lungs is similar to that of mammals and birds, even at identical ventilation rates, in spite of their simple lung morphology.