Fig. 10. Combined tracheal–haemolymph buffer capacity for CO₂ in Drosophila estimated from the amount of flight-specific CO₂ released after flight stop. Respiration was limited to gas exchange through the abdominal spiracles (thoracic spiracles sealed). (A) In a single fly, CO₂ release decayed exponentially after flight stop and approached zero after 40 s. The area under the curve = CO₂ buffer capacity of the tracheal system and haemolymph (light grey). Red line represents first-order exponential fit to data. (B) CO₂ buffer capacity per gram body mass (35 flight sequences, 6 flies) derived from estimations of the area under curve after flight stop (as shown in A). Data are plotted as a function of pre-resting flight force produced during the last 2 s before the animals ceased to fly. Blue line indicates mean value ± s.d. (shaded grey).