28 A BIOMETRIC STUDY OF BASAL METABOLISM IN MAN. 



At the present time it is generally admitted by students of metab- 

 olism that for the short observation periods, which are essential for 

 the measurement of the individual in a state of complete muscular 

 repose and in the post-absorptive condition, the errors of computation 

 of heat-production by the indirect method are actually less than those 

 of direct measurement in the calorimeter. 9 



We have expressed total heat-production in calories per 24 hours. 

 This has seemed to us the most desirable unit for a universal standard. 

 In employing this unit of time there has been no attempt to obscure 

 the fact that the actual measurements covered shorter periods. In 

 practically all cases, however, the 24-hour constant is based upon 

 a number of periods. 



Since in indirect calorimetry the thing actually measured is the 

 gaseous exchange, we have worked out and discussed the chief statis- 

 tical constants for the measures of gas volume as well as for the total 

 heat-production indirectly derived from them. Anyone who may be 

 inclined to discredit the results as expressed in calories computed by 

 the formulas of indirect calorimetry may see our chief conclusions 

 established by the constants based on the directly measured gaseous 

 exchange. 



In passing, it is worth while to note that the high degree of con- 

 sistency in our oxygen and carbon-dioxide measurements affords strong 

 evidence for the trustworthiness of our constants. 



The coefficients of correlations between oxygen consumption and 

 carbon-dioxide excretion in the adults 10 are given in table 4. 



TABLE 4. Correlation between two measures of gaseous exchange. 



9 A review of the problem of direct and indirect calorimetry is given by Krogh, The Respira- 

 tory Exchange of Animals and Man. Longmans, Green and Co., London, 1916, p. 9. 

 Because of the technique in the measurement of oxygen consumption and carbon-dioxide 

 production necessarily adopted in the case of infants, we have not been able to include 

 the correlations for these series. 



