DIGESTIBILITY AND AVAILABILITY OF FOOD. 



239 



the calorimeter period. In the majority of cases, however, the 

 variations of the individual experiments of one kind with any 

 subject from the average of all the experiments of that kind 

 with the same subject are small. In like manner the averages 

 of the same kind of experiments vary so little with the differ- 

 ent subjects that all the experiments of one kind may be ar- 

 ranged for all the subjects together, and the averages of the 

 different kinds of experiments may be compared as follows: 



Cojnpariso7i of averages of restilts of experime?its with different 

 degrees of muscular activity. 



Energy. 



Rest experiments within the calorimeter, 

 Rest experiments outside of calorimeter, 

 Work experiments outside of calorimeter, 

 Work experiments within the calorimeter. 



90.5 



89.9 



92.1 

 92.6 



These results indicate that the amount of work performed 

 had no effect upon the availability of the nutrients of the diet. 

 The average coefficients of availability of carbohydrates are 

 very close for all four kinds of experiments; those for fat are a 

 very little larger in the work experiments than in the rest ex- 

 periments; those for protein are quite noticeably smaller in the 

 work experiments. The latter difference is due, however, not 

 to the increase in the amount of work, but to a decrease in the 

 amount of animal protein in the diet. In the majority of the 

 work experiments the quantities of vegetable foods were in- 

 creased, and the proportion of the protein of the diet supplied 

 in vegetable foods was much larger than in the rest experi- 

 ments. Because of the lower digestibility of the vegetable 

 protein, it would be expected that the coefficients found for the 

 whole diet would be smaller than in the experiments in which 

 the proportion of animal protein in the diet was larger. This 

 is especially true of the larger part of the experiments follow- 

 ing No. 195. By referring to Table 134, it will be observed 

 that these are the ones in which the coefficients of availability 

 of protein are lowest. 



