94 



METABOLISM AND NUTRITION 



gations still further (1894). By the use of the calorimeter he determined 

 on dogs (direct calorimetry) the amount of heat lost, and at the same time 

 estimated from the excreta the total metabolism (see page 92) ; then, from 

 the calorific values of the foodstuffs, he calculated the amount of heat pro- 

 duction (indirect calorimetry) in the body represented by this metabolism. 

 The result was that in eight series of experiments covering altogether forty- 

 six days the mean difference between the heat production as calculated from 

 the metabolism and the heat loss determined by the calorimeter was only 

 0.3 per cent. 



In some very careful experiments with men on a mixed diet Atwater 

 has obtained similar results. In these experiments not only were the food and 

 the total excreta analyzed, but the calorific values of the food, the urine and 

 the fasces were determined directly; and at the same time the heat given off 

 by the subject was measured by the calorimeter in which he was confined. 



In the following table are summarized experiments taken at random from 

 Atwater's papers, and in parallel columns are placed figures representing 

 (1) the amount of "heat production as calculated by him, and (2) the amount 

 of heat loss determined directly. Besides, in order to test by these observations 

 the heat values of the organic foodstuffs as given by Rubner, which are 

 generally accepted as standard, we have calculated from Atwater's data the 



MEAN PER DAY 



