A suitable and satisfactory determination of the basal metabolism requires (1) an accurate measurement of the carbon dioxide elimination or of the oxygen consumption and (2) a resting, quiet subject. In young children and in infants both of these factors present different problems than in adults. The mouthpiece, or mask, is not feasible for infants, and a chamber, or box, is usually used. Infants produce much less carbon dioxide than adults, and for accurate gravimetric determinations of the carbon dioxide production rather long periods of at least from thirty to sixty minutes have been required. The average baby or small child usually is restless or may cry, especially if under observation for some time; this is undoubtedly the main difficulty and source of error in determining their basal metabolism.
During the past year at the children's clinic of the Massachusetts General Hospital, a new method of determining the basal metabolism