Digestion — Respiration — Calorimetry — Energy. 45 



One day's study xvith a 1570-lh. ox in a respiration apparatus. 



lungs and skin exhaled 49.5 lbs. of gas and vapor, a little over half 

 of which was water and a little less than half carbonic acid gas. 

 The total outgo for 24 hours was 169.5 lbs. 



A considerable part of the food was not digested, but passed off 

 as the so-called solid excrement and so was useless. The larger 

 part, however, entered the body proper from the stomach and in- 

 testines, and was used to carry on the life functions, repair the 

 wasting tissues, etc., and passed off as waste after being so used. 

 A small portion only was stored as body substance, as we shall see 

 later. 



