Abstract
Evidence obtained from previous studies suggests that one of the factors which influence the affinity of amphibian haemoglobin for oxygen is the locus of erythrocyte formation (Barcroft, 1934; Hall, 1934). It has been shown for the developing bullfrog (McCutcheon, 1936), and also for different species of the class Amphibia (McCutcheon & Hall, 1937), that the oxygen dissociation curve shifts from left to right depending upon the extent to which the specimen is aquatic, semiaquatic, or terrestrial.