Harald T. Andersen

THE EFFECT OF CARBON DIOXIDE ON THE RESPIRATION OF AVIAN DIVERS (DUCKS).

Abstract 1. 1. The normal respiratory effect of CO2 in avian divers has been studied. Domestic ducks (“white Pekin”) served as subjects. 2. 2. The respiratory minute volume (RMV), tidal volume (TV) and respiratory frequency (RF) were recorded. 3. 3. The RMV almost always increased when the ducks breathed gas mixtures with a high content of CO2. 4. 4. The RMV rose due to an augmentation of TV which more than compensated for the tendency of RF to decrease with increasing CO2-concentrations in the inspired air. 5. 5. These findings confirm the observation by Orr & Watson (1913) and Hiestand & Randall (1941), who found that high concentrations of CO2 in the inspired air cause transient periods of apnoea in the duck. However, they do not support the conclusion that CO2 is a respiratory suppressor in diving birds, for the RMV was not reduced until the CO2-concentrations inhaled were raised well above those found in the lungs of diving ducks (Andersen, 1959).