Vt ig 
INVESTIGATIONS ON METABOLISM. BG 
total food eaten, 79 grams of protein and 3,125 calories of 
energy. ‘These quantities are estimated to correspond to about 
71 grams of protein and 2,955 calories of energy in the food 
actually digested. 
These observations, taken in connection with the differences 
of occupation, are of interest in comparison with the figures of 
the tables above. In tables 15 and 16 the results are put 
together in such form as to bring out more clearly the com- 
parisons between the quantities of nutrients and energy in the 
food, the quantities actually consumed by the body, and the 
gain or loss by the body in each case. ‘The figures for experi- 
ment 4 are computed on the basis of 30 hours’ lag in the urine. 
It will be observed that the laboratory janitor, who was 
accustomed to moderately active muscular work, ten hours per 
day, and who was what would be called a “‘hearty eater,’’ 
consumed during the first experiment 122 grams of the 136 
grams of digestible protein in his food, and at the same time 
stored the remaining 14 grams according to the calculations of 
these experiments. Of the 2,960 calories in the food digested 
he consumed material corresponding to 2,310 calories. ‘The 
digested nutrients of the food furnished an excess of carbo- 
hydrates and fats as well as protein, so that his organism 
stored fat and protein corresponding to 650 calories of energy. 
In the second experiment his diet was reduced so as to supply 
only 110 grams of digestible protein and 2,645 calories of 
energy. In this case his organism was estimated to consume 
113 grams of protein, a trifle more than the food supplied, and 
2,440 calories of energy. The organism gained considerable 
fat, enough to make a gain of material corresponding to 205 
calories of energy. 
The subjects of experiments 3 and 4, who were accustomed 
to only light muscular activity as is natural with their profes- 
sional work, chose for their diet materials computed to supply 
95 and 93 grams of digestible protein and other digestible 
nutrients sufficient to furnish about 2,500 calories of energy 
per day. When at rest in the respiration apparatus or engaged 
in either light or severe mental work, they consumed from 79 
to 86 grams of protein and from about 2,500 to 2,700 calories 
of energy. ‘This consumption must have been reasonably eco- 
nomical, since the amounts of nutrients available were so small. 

