P. W. Wilson, in his recent monograph (‘The Biochemistry of Symbiotic Nitrogen Fixation’, 1940), includes some data on the oxygen-intake in respiration of nodules, roots, and tops of several leguminous species. He also presents a critical discussion of the method of calculating the energy requirements of fixation employed by Allam (see above) and also by W. B. Andrews in a recent paper (‘Effect of ammonium sulphate on the response of soybeans to lime and artificial innoculation and the energy requirement of soybean nodule bacteria.’ Jour. Amer. Soc. Agron., 29, 681–9, 1937).