198 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



temperature under all conditions of external environment, the natural 

 inference was that the heat production was determined by the heat 

 lost, and the heat lost was, in turn, determined by the number of square 

 centimeters of surface exposed to the environmental temperature. 

 The early promulgation of this idea by Rameaux^ and later by Berg- 

 mann,^ unsubstantiated, it is true, by experimental evidence, was fol- 

 lowed in 1883 by a series of remarkable experiments by Rubner,^ who 

 altered the environmental temperature and studied the basal metabo- 

 lism under these conditions. The law of surface area, as finally enun- 

 ciated by Rubner, and almost simultaneously by Richet,^ was to the 

 effect that the heat production of warm-blooded animals is essentially 

 proportional to the surface. So attractive did this general thesis appear 

 that E. Voit^ made the claim, based upon computations and fragmen- 

 tary metabolism measurements on various animals, that this law held 

 true whether the living organism was a horse or a hen. In other words, 

 he computed that approximately 1,000 calories per square meter per 

 24 hours were given off by an animal. This figure became so fixed in 

 the minds of physiologists as to be almost a fetish, and every effort has 

 been made to utilize it for practical purposes, particularly in the com- 

 parison of pathological measurements with "a. normal standard." 



The desirability of having a standard figure for comparison with 

 pathological cases admits of no argument. That such a standard 

 figure actually exists is, however, open to serious argument, for it re- 

 quires the assumption that there is a constant basal metabolism per 

 unit of body-surface. Furthermore, the advocates of the law of sur- 

 face area give little recognition to the fact that at least 25 per cent of 

 the heat produced during conditions of repose is lost by the vaporiza- 

 tion of water from the lungs and skin, warming of the expired air, etc. 



One diflficulty in interpreting metabolism data has been the lack of a 

 suflScient number of individuals who have been studied under com- 

 parable conditions to provide values with the high degree of accuracy 

 required for the deduction of such important factors as the relationship 

 between the heat production and the body-weight or the heat pro- 

 duction and the body-surface. Recently values obtained with over 

 150 men and women were brought together and charted.® These 

 measurements were made for the most part in the Nutrition Labora- 

 tory, and all were secured with the subjects in complete muscular 

 repose and in the post-absorptive condition. The general picture 



1 Rameaux, Bull. Acad, de med., Paris, 1838-39, 3, p. 1094; Bull. Acad. roy. d. sc. de Brux., 



1839, 6, p. 121; Mem. Couron. Acad. d. sc. de Belgique, Brux., 1856-58, 29, 64 pp. 



2 Bergmann, Uber die Verhaltnisse der Warmeokonomie der Thiere zu ihrer Grosse, Gottingen, 



1848. 



3 Rubner, Zeitschr. f. Biol., 1883, 19, p. 535. 



* Richet, La chaleur animale, Paris, 1889. His earlier writings are here summarized. 

 «Voit, Zeitschr. f. Biol., 1901. 41, p. 120. 



'Benedict, Emmes, Roth, and Smith, Journ. Biol. Chem., 1914, 18, p. 139; Benedict, ibid., 

 1915, 20, p. 263. 



