METABOLIC MINIMUM 483 



proved that the idea of a "normal dietary allowance" is de- 

 cidedly misleading, as the amount of food which a man needs 

 depends primarily upon the amount of muscular labor which 

 he has to perform. 2 Buhner, for instance, divides his human 

 observation material into four classes according to the type 

 of occupation. To the first class belong persons with seden- 

 tary occupation (as brokers, the learned professions, mer- 

 chants, writers, textile workers and those who attend 

 machines) ; such individuals require about 2400 calories. 

 To the second group he refers workers who either work 

 standing, or engage in rather severe labor in sitting posi- 

 tion; these need about 3000 calories. The third class in- 

 cludes individuals whose labor demands more physical 

 strength (masons, smiths, soldiers in forced marches) ; these 

 requiring accordingly a larger amount of food, about 3400 

 calories. In the fourth class finally, individuals are placed 

 who are required to perform especially heavy labor (as 

 farmers, porters and persons who undertake heavy athletic 

 feats) ; in these a calory requirement of from 4000 to 5000 

 commonly is met. Even this does not cover the extreme 

 demands. Atwater has met American woodsmen who easily 

 required 7000 to 8000 calories ; and there is record of a man 

 who rode a bicycle for sixteen hours with the imposing 

 record of 9000 calories. 



Metabolic Minimum. What is the metabolic minimum 

 for man? Eecent studies by Zuntz and Tigerstedt 3 show 

 the metabolic minimum of the adult individual as about one 

 calory pro kilogram per hour. This would mean about 1700 

 calories for an individual of seventy kilograms weight. This 

 estimate tallies fairly with the direct results of respiration 

 studies conducted by Sonden and. Tigerstedt upon indi- 

 viduals in sound sleep, and by Zuntz and Lehmann upon 



2 Cf. also A. Slosse and E. Waxweiler (Instit. Solvay, Brussels; Travaux 

 de 1'Instit. de Sociol.). Observations upon the nutrition of more than 1000 

 Belgian laborers. 



8 R. Tigerstedt (Helsingfors), Skandin. Arch. f. Physiol., 23, 302, 1910; 

 E. Koch (Tigerstedt's Lab.), ibid., 25, 315, 1911. 



