THE STORY OF OUR FOODS 27 



specially consumed in the act of bodily work. 

 Estimating the height of the Faulhorn Mountain as 

 10,000 feet, the basis of their experimentation took 

 the shape of the investigation of the amount of 

 bodily waste given off by a man, weighing 140 pounds, 

 climbing the mountain. This of course represented 

 a measured piece of work: the raising of a man's 

 own weight (140 pounds) 10,000 feet high. Paying 

 attention to the amount of waste matter which 

 was given forth in the accomplishment of this 

 task as compared with that excreted at rest, they 

 arrived at certain definite conclusions. We have 

 to bear in mind that as the two classes of foods 

 are used up in the living body, two different kinds 

 of waste are given forth as the result. The nitro- 

 genous foods give off waste chiefly by the kidneys, 

 this waste material being represented by a substance 

 known as urea, which represents in itself the final 

 stage, so to speak, in the breakdown of nitrogenous 

 substance in the body. On the other hand, the 

 waste of the non-nitrogenous foods is represented 

 by substances given forth from the lungs, skin, 

 and in part by the kidneys. These are in chief, 

 heat, water, and carbonic acid gas. The problem 

 being thus fairly defined, the two experimenters 

 carefully calculated the amount of waste of the 

 two kinds specified during their periods of rest 

 and during their climbing of the mountain respec- 

 tively. The result was the discovery that the 

 amount of urea, that is, the waste of nitrogenous 

 food, did not materially alter whether they were at 

 rest or whether they were engaged in their active 

 exercise. On the other hand, the waste of non- 

 nitrogenous kind increased very materially during 

 their periods of activity, and decreased during their 



