NUTRITIVE FUNCTIONS. 



285 



waste, and therefore to grade of life and intensity of 

 work. This is expressed in formula 4: 



4. Food oc Waste oc Life and Work. 



Therefore life in a scale pan would show a continual 

 oscillation of level — i. e., of weight of body. In adults, 

 whose supply is only equal to waste, the average weight 

 is maintained ; in a child the supply is a little greater 

 than the waste, and the average weight increases. 



Observe that the most fundamental of these two op- 

 posite processes is the waste. This is continuous with 

 life and apparently its cause; the other (supply) is oc- 

 casional. The waste goes on continuously, whether 

 there be supply or not, as long as life lasts. The sup- 

 ply may be regarded as a secondary consequence of 

 the waste. 



Illustrations. — 1. Thus the living animal body may be 

 compared to a burning lamp — ever consuming and ever 

 resupplied. In both cases there is waste and supply, 

 and in both cases there is continual oscillation of weight. 

 In both cases heat is produced by the consumption of 

 material. Moreover, the amount of heat produced by 

 the burning of a pound of material is substantially the 

 same in the two cases, only in the one case the heat is 

 concentrated on a given point and compressed into a 

 short time, and is therefore intense, while in the other it 

 is spread over the whole body and stretched over twenty- 

 four hours, and is therefore less intense at one time and 

 place. 



2. Again, the living body may be compared to a 

 temple on which are constantly engaged two opposite 

 forces — the one tearing down, the other repairing; the 

 one instructive, the other obstructive; the more rapid 

 the destruction, the more active the construction. These 

 two go on with varying success until at last the de- 



