DEVELOPMENT OF RESPIRATION IN THE DUCK

Abstract

CO2 excites acceleration of respiratory rate when it acts by way of vascular channels but produces marked inhibition and slowing of respiration when taken into the lungs of unhatched air-breathing ducks. Deficiency of O in the inspired air results in acceleration of the respiratory rate. Pulmonary respiration, which normally starts about 3 days before the end of incubation, appears to be initiated by the excitatory effect of metabolic CO2 accumulating during the state of partial anoxemia which accompanies the physiologic deterioration of the respiratory allantois. The initiation of respiration may be facilitated by the excitatory action of O deficiency.