/ BASAL METABOLISM. 83 



the subject drank water, and urine collections were sometimes made. 

 During the greater part of the time the subject read quietly or slept. 

 The results of the experiments with the bed calorimeter may thus con- 

 sistently be used as evidence of an approximate basal metabolism 

 i. e., the minimum metabolism with nearly complete muscular repose 

 and in the post-absorptive condition. 



All of the Boston experiments were made with the subject in the post- 

 absorptive condition (12 hours after food). Furthermore, it was pos- 

 sible in these experiments to obtain a graphic record of the muscular 

 activity by means of a pneumograph fastened around either the chest 

 or the thighs and connected with a tambour outside the chamber. 

 Inasmuch as the air volume of the two calorimeters used in Boston was 

 smaller than that of the Middletown apparatus and the subject was 

 considerably quieter, the measurements could be made with a higher 

 degree of accuracy, especially as the activity was controlled by means 

 of the graphic record. It was thi*s possible to subdivide the experi- 

 ment into shorter periods and to obtain values per hour or per three- 

 quarters of an hour instead of for 2 hours, as with the Middletown 

 experiments. 



While the duration of the Boston experiments was approximately 

 the same as that of the Middletown experiments considered in this 

 section, the general plan was changed in that the basal metabolism 

 was first determined for a number of periods, then the food was given, 

 and the experiment was continued for the remainder of the 8 hours. 

 The basal metabolism and the metabolism after food were thus deter- 

 mined on the same day in continuous measurements. This plan was 

 followed with nearly all of the food materials studied except beefsteak. 



Certain of the experiments were continued for periods longer than 

 8 hours in order to obtain further information as to the probable varia- 

 tion from hour to hour. In many instances observations were made 

 with the same subject at intervals for many months or even years; 

 a hint could thus be obtained as to the possibility of seasonal or yearly 

 variations. 



The first extended experiment in which the chair calorimeter was 

 used was that made with J. R., December 3, 1908, although this appa- 

 ratus had been tested in shorter experiments prior to this date. The 

 results of this experiment, together with those of five other experiments 

 with the same subject, are given in table 29. In this and the succeeding 

 tables, the day is divided into hour periods, the results obtained in the 

 individual periods being placed in the table according to the time the 

 observations were made. Average values are also given both for the 

 experimental periods and for the values obtained in the individual 

 periods in all of the experiments. In considering the latter averages, 

 it should be borne in mind that some of the individual values were 

 determined several months or years apart. 



