THE TOTAL EXCHANGES OF THE BODY 



665 



expired air gives the respiratory metabolism during the time of the observation. 

 The bag is carried on the back of the individual, so that it does not interfere with his 

 movements. This method has been used for determining the metabolism of soldiers 

 in training, of munition workers, etc. 



By means of one or more of these methods we may arrive at a correct 

 idea of the total income and output of an individual for periods of many 

 days. The following details by Tigerstedt may serve as an example of the 

 results obtained in such an experiment. The experiment lasted two days. 

 The subject was a man of twenty-six years of age, weighing about 65 kilos, 

 who had previously taken no food for five days. The following Tables 

 represent his material income and output. 



Valve 



Corrugated 

 rubber 

 tubing 



2 way tap 



Side tube for 

 sampling (tvi'th clip)~ 



Headpiece 

 Mouthpiece 



FIG. 330. Douglas' Bag for determining respiratory exchange in man. 

 TOTAL INCOME 



