ALIMENTATION AND THE EXPENDITURE 161 



G. Weiss ( x ) came to the same conclusion : instead of man he 

 took an animal which does not, normally, maintain its tempera- 

 ture constant : namely, the frog. After feeding it with glucose, 

 butter, or lean meat, he measured its consumption of oxygen. 

 He obtained the following proportions : 



100 107 153 



which recall Rubner's specific dynamic actions. 



Atwater and Benedict ( 2 ) found that the consumption of oxygen 

 by man when fasting (one lives, in this case, on one's reserves of 

 fat) is 30-79 gr. to produce 100 Calories, and is 28-88 gr. with a 

 ration containing 75% of carbo-hydrates. A ratio of 100 to 107. 

 The experiment has not been attempted in the case of the pro- 

 teids, because of the difficulties of ensuring the expenditure of 

 pure proteids before the reserves of fat and carbo-hydrates are 

 exhausted. All experimentalists have recognised that an excess 

 of proteids causes an excessive absorption of oxygen, and Chau- 

 veau summed up the facts when he said : " The digestion of food 

 causes a superconsumption of oxygen, indicative of an increase 

 of the energetic expenditure of the animal economy : an increase 

 that is small with carbo-hydrates, larger with fats, but obviously 

 the greatest in the case of albuminoids." ( 3 ) 



108. Variations in the Expenditure. If the nature of the ali- 

 mentation influences the magnitude of the expenditure, there 

 are other causes of variation that are still more important : 



1. The Amount of Mechanical Work.- This is evident, and it 

 will be analysed completely later. 



2. The Mass of the Body.- This mass has as its dimension ? 8 , 

 whilst the surface of the body has as dimension r 2 ; small statures 

 have therefore relatively a greater surface ; and as the radiation 

 increases with the surface, the heat will accordingly follow the 

 same law. Hence, for small statures, it is necessary to regulate 

 their temperature more actively and to have more intense com- 

 bustion. This is called " The Law of Surfaces." It can be con- 

 cluded that, per kilogramme of its weight, the child expends 

 more than the adult. We give below a table giving the ex- 

 penditure for various weights of the body. Some special subjects 

 having an insufficient muscular bulk relatively to their surface 

 (obesity), or an excess of that surface (very thin people), are in- 

 cluded. They are all taken in a state of repose. 



(!) G. Weiss (Journ. de PhysioL, 1910, p. 408 ; Rev. Gen. Sc., 1910, p. 19). 

 .(*) Atwater and Benedict" (Bulletin, No. 136, p. 167, 1903). 



( 3 ) A. Chauveau (Compt. Rend. Acad. Sc., 28th Jan., 1907, p. 173). Cf. 

 Laulanie, Clements de PhysioL, 1905, p. 561 ; J. Amar (Journ. de PhysioL, 

 1912, p. 307), Lafon (C. R. Sc., March-A ril, 1913). 



