“…This is due to the multiplicity of metabolic events concerned in the conversion of a metabolite to C02, and in the subsequent transport and elimination of this CO2 from the body. The complexities of the processes involved in the excretion of C02 have been investigated (Kornberg, Davies & Wood, 1952; Steele, 1955;Robinson & Coxon, 1957; Shipley, Baker, Incefy & Clark, 1959; Coxon & Robinson, 1959a) and these data have been used in the interpretation of experiments in which the oxidation of various labelled compounds injected intravenously was studied (Baker, Shipley, Clark, Incefy & Skinner, 1961;Coxon & Robinson, 1959b; Steele, Altszuler, Wall, Dunn & de Bodo, 1959).…”