DIGESTIBILITY AND AVAILABILITY OF FOOD. 237 



Apparently the sojourn within the calorimeter had little in- 

 fluence upon the digestibility of the diet. In comparing the 

 results of the different experiments with the same subject, 

 given in Table 134 above, it will be noticed that in some in- 

 stances the coefficients were smaller, and in others larger in 

 the calorimeter than in the preliminary period. In a few of 

 the experiments the differences were quite appreciable, but in 

 most of them they were small; and generally the differences 

 between preliminary and calorimeter periods were smaller than 

 those between two experiments in the same period, as will be 

 seen by comparing the agreement of the averages in the above 

 table and that of individual experiments of Table 134. The 

 averages for the preliminary and calorimeter periods for the 

 same subject were reasonably close. In the averages of all 

 the preliminary experiments with all these subjects and all the 

 calorimeter experiments with all the subjects, the differences 

 are practically negligible. That is to say, so far as the utiliz- 

 ing of the food was concerned, it made practically no difference 

 whether the subject was confined in a small room or was free 

 to move about without limit. 



Influence of vmscidar zvork 2ipon availability . — The experi- 

 ments in which the amount of muscular activity was least were 

 the rest experiments within the calorimeter. In these the sub- 

 jects remained as quiet as they could during the greater part of 

 the time; their muscular exercise consisted chiefly of that in- 

 volved in writing, taking observations of body temperature, 

 etc., caring for food and excreta, and folding or unfolding the 

 chair, table or bed as needed. In later experiments the amount 

 of work was even smaller than in the earlier ones, because the 

 subjects dressed onl}- in underclothing, to avoid the expendi- 

 ture of energy involved in putting on and taking off their 

 outer garments. The total amount of work performed each 

 day during the rest experiments within the calorimeter was 

 far less than that of a man at any ordinary sedentary occupation. 



During the days preliminary to the rest experiments within 

 the calorimeter the subjects avoided all unnecessary exertion, 

 but were engaged in their usual occupations, which with E. O. 



