160 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



tions as to the existence of a causal relationship between surface-area 

 and heat elimination. 



Nearly all of our records of the surface areas of the children in this 

 research, especially those for children above 1 year of age, 1 are based 

 upon actual measurements of the surface-area by the Du Bois linear 

 formula, and hence represent true physical measurements rather than 

 computations from body-weight, which so long supplied the only 

 basis for body-surface estimates. With our children, therefore, this 

 accurately determined physical measurement may legitimately be 

 employed exactly as we used the body-weight; if we so chose, we 

 could likewise use the stature. Since the preponderance of evidence 

 is slightly in favor of the correlation between body-surface accurately 

 measured and basal metabolism on the one hand, and body-weight and 

 basal metabolism on the other, a comparison of the surface-area and 

 total metabolism is of physiological interest. 



For practical use it is highly desirable to determine a normal trend 

 of basal metabolism referred to some simply measured factor, such 

 as weight, for the purpose of predicting the heat production of a subject 

 whose weight is known but whose metabolism has not been measured. 

 The multitudinous measurements involved in the Du Bois linear for- 

 mula may therefore, in many instances, rule out the possibilities of 

 comparing the measured surface-area and the total metabolism, or 

 using the measured surface-area as a unit for estimating basal meta- 

 bolism, as has so long been attempted from either body-weight or 

 from the surface-area as computed by the Meeh formula. 



In discussing our values on the basis of body-surface, it should be 

 emphasized again that body-surface must be looked upon simply as a 

 physical measurement approximating perhaps more closely the 

 general morphological law of growth than does body-weight, and 

 hence by this very fact, perhaps, giving a somewhat better idea of 

 the relationship between the mass of active protoplasmic tissue and 

 heat production than would the weight alone. We believe there is 

 no causal relationship between body-surface area and heat production. 

 All of our experimental evidence, not only for children but for adults 

 under various conditions of nutrition, implies that the production of 

 heat in the body is not determined by the loss. Even if it were granted, 

 for the sake of argument, that the reverse is true, the physical and 

 physiological factors influencing the heat loss from the surface of the 

 human body are so different at different parts of the body as to pre- 

 clude any generalization that equal areas result in equal heat loss. 

 With this explanation clearly in mind, we may proceed to an analysis 

 of the data obtained in this study, using the measured body-surface 

 area as the unit of reference. 



1 For 20 boys and 19 girls, nearly all of them very young, the body-surfaces were computed by 

 the Lissauer formula. The data given for these children do not therefore represent actual 

 measurements. (See tables 27 and 28, pp. 116 and 120.) 



