A CRITIQUE OF THE BODY-SURFACE LAW. 145 



the measured metabolism of individuals of known or estimated body- 

 surface, the situation seems to be about the following. 



Series of measurements of basal metabolism have been made and 

 expressed in calories per individual, per kilogram of body-weight, and 

 per square meter of body-surface for definite periods of time. The 

 number of calories produced by individuals varies greatly. When 

 reduced to a standard of calories per square meter of body surface, the 

 heat-production varies much less widely than when the original meas- 

 urements are left entirely uncorrected for the size of the individual 

 experimented with. 



Workers of one group look at such series of values and seeing the 

 great increase in uniformity of results which has been secured by the 

 correction for body-surface exclaim, "The heat production of an indi- 

 vidual per unit of body-surface is a physiological constant." Workers 

 of another group, however, see the differences which still obtain be- 

 tween the measurements based upon a number of individuals and reply, 

 "Certainly, with differences of such magnitude, no one can speak of 

 calories per square meter of body-surface as a physiological constant." 



Thus the two groups are apparently in a state of controversial 

 dead-lock which can not be broken by the willingness of one or the 

 other, or of both, parties to look at the other side of the shield, for 

 both groups are already examining the same surface. One group sees 

 in it regularity, the other irregularity. What constitutes regularity 

 as contrasted with irregularity is a matter of personal opinion and must 

 always remain so until some quantitative criterion is adopted. 



The expression of the amount of heat produced in terms of number 

 of calories per square meter of body-surface is, in its final analysis, 

 merely an attempt to correct for the most significant proximate factors 

 in the determination of heat-production. Since body-surface has the 

 weight of tradition in its favor, it is perhaps naturally assumed to be 

 the most significant factor. But suppose that body-surface is not the 

 most significant variable physiologically? Certainly, it should not 

 then be used as the corrective term. 



The first step in determining the most potent physiological factor 

 underlying heat-production would seem to be the actual measurement 

 of the intensity of relationship between the various body measurements 

 that may reasonably be suggested as influencing metabolism and total 

 heat-production. We shall then be in a position to consider what 

 measurement of this kind, or what combination of measurements, is 

 most suitable for use as a corrective term to be applied to gross values 

 of basal metabolism obtained from series of human individuals. 



As far as we are aware, the most quantitative test 63 which has ever 



63 After this manuscript was nearly completed a paper by Armsby and his associates, in which 

 correlations for body-weight and heat-production and body-surface and heat-production were 

 given for the original Nutrition Laboratory series, appeared. Armsby, Fries, and Braman, Proc. 

 Nat. Acad. Sci., 1918,4, pp. 3-4. See also Journ. Agr. Res., 1918, 13, pp. 49-55. 



