A CRITIQUE OF THE BODY-SURFACE LAW. 137 



surface physique. Cela montre que la connaissance de la surface ge'ometrique 

 d'un animal est insuffisante pour qu'on en puisse de'duire la perte par rayonne- 

 ment: il faut encore tenir compte de l'e"tat de la circulation pe'riphe'rique. 



In 1888 v. Hoesslin 33 pointed out that while in warm-blooded 

 animals variations in the external temperature are followed by varia- 

 tions in metabolism, the change in heat-production is not proportional 

 to the change in external temperature. Thus heat-loss is not deter- 

 mined solely by difference in body-temperature and air-temperature, 

 i.e., by differences in potential, v. Hoesslin considers this a valid 

 refutation of Rubner's theory. 



Richet, in his volume of 1889, 34 treated the problem of metabolism 

 under varying external temperature. The reader interested in details 

 may refer to this work or to a more recent discussion of the problem. 33 



We now turn to the question of the influence of internal condition 

 on metabolism in its relation to the problem of the validity of the body- 

 surface law. We shall here consider the problem as to whether, when 

 body-surface remains practically constant but other conditions vary, the 

 heat-production per square meter of body-surface area is a constant. 30 



Against this line of argument is to be urged the fact that in an 

 early consideration of the body-surface law Rubner insisted upon 

 uniformity of physiological state. 37 While in more recent writings the 

 constancy or equality in the nutritional level has from time to time 

 been emphasized as a prerequisite for the applicability of the law of 

 surface-area, this has by no means been generally considered, and current 

 practice has tended to accept the universality of this law irrespective 

 of whether the individual is poorly or well nourished. 



As early as 1888 v. Hoesslin 38 pointed out that a dog (studied in 

 the respiration chamber by Pettenkofer and Voit) required 1600 calories 

 per day for maintenance of body- weight. On the sixth day of inanition 

 it used only 1190 and on the tenth day only 940 calories. Body- weight 

 decreased from 33 to 30 kg. If the body-surface law holds, the heat- 

 production of the two periods should stand in the ratio "S/33 2 : \/30 2 or 

 10.288 : 9.655, or there should be a decrease in heat-production of 



-6.15 per cent. 



S/33 2 

 As a matter of fact there is a decrease of 41.25 per cent. 



33 v. Hoesslin, Arch. f. Anat. u. Phys., Phys. Abt., 1888, pp. 327-328. 



34 Richet, La Chaleur Animale, Paris, 1889; especially Chapter XI. 

 -'" Richet, Chaleur, in Dictionnaire de Physiologic, 1898, 3, p. 138. 



36 Here only published materials are taken into account. An extensive series of under- 

 nutritiou experiments made on a group of 25 men was carried out through the winter of 1917-1918 

 by the Nutrition Laboratory. The problem of the relation of nutritional state to metabolism is 

 considered in detail in the report of these experiments. See Benedict, Miles, Roth, and Smith, 

 Human vitality and efficiency under prolonged restricted diet, Carnegie Inst. Wash. Pub. 

 No. 280. (In press.) 



37 Rubner, Archiv. f. Hyg., 1908, 66, p. 89. 



38 v. Hoesslin, Arch. f. Anat. u. Phys., Phys. Abt., 1888, p. 331. 



