952 



NUTRITION AND HEAT REGULATION. 



room, but provision is made for absorbing the COz and water as 

 it is formed, and for adding new oxygen from an oxygen tank as it 

 is needed. This arrangement is represented schematically in 

 Fig. 301a. By means of this apparatus many interesting and 

 important experiments have been made upon the nutrition of 

 man under different physiological and pathological conditions, 

 and it seems probable that it will supplant entirely the earlier 

 forms of calorimeter described in the preceding pages. As an 

 indication of its sensitiveness the following result may be quoted 



RESPIRATION CHAMBER 

 used 



o z o deficient \ 



introduced 



, 4. 

 O deficient 



J COz LJ H*0 

 absorbed by absorbed by 



n 



Fig. 301a. Diagram of circulation of air through respiration apparatus. (Atwater and Benedict.) 



from observations made upon a man who, while in the apparatus, 

 did much muscular work on a bicycle ergometer: 



Income: Potential energy of material metabolized n oy 

 Out f Energy given off from the body as heat. . . . 4833 Cal. 

 Ulgo 



bod 



f Energy given off from the body as heat. . . . 483 

 \ Heat equivalent of muscular work ......... 602 Cal. 



5435 Cal. 



5459 CaL 



5435 Cal. 



Experimental error ........................ 24 Cal. 



Results of Calorimetric Measurements. The actual results 

 obtained from direct calorimetric measurements corroborate those 

 deduced from the study of the energy given off in the oxidation of 

 the foodstuffs of the daily diet. They show that man under con- 

 ditions of ordinary life gives off heat from his body to the amount of 

 about 24 calories per kilogram of weight during twenty-four hours, 

 that is, about 1 calorie per hour per kilogram of body weight.* 



* Benedict, et al, "Journal of Biological Chemistry," 18, 139, 1914. 



