GASEOUS METABOLISM DURING REST. 491 



in Springfield, these measurements including observations of the 

 oxygen consumption and in many cases of the carbon-dioxide produc- 

 tion. In addition, the carbon-dioxide output of the squad as a group 

 was measured biweekly during sleep in a large respiration chamber in 

 Boston. Since in the Springfield measurements, the subjects were 

 always in the post-absorptive condition — that is, without food for at 

 least 12 hours — we have clear records of the basal metabolism. The 

 experiments made in Boston during the night were not strictly basal 

 in that they did not conform to the fullest demand for the post-ab- 

 sorptive condition, since the experiment began less than 12 hours 

 after the preceding meal. On the other hand, the measurements were 

 made for the most part during deep sleep and after a very light supper 

 and in all probability they represent the basal demand. 



It was extremely important to determine the basal metabolism 

 prior to the dietetic restriction and thus establish the normality of 

 these men and find whether the variations in metabolism were within 

 the so-called normal limits. As has been frequently pointed out in 

 this monograph, the period for the measurement of basal values during 

 normal diet was too short with all factors studied in this research. 

 Since there was a possibility that it might be necessary to conclude 

 the observations at Christmas, we were obliged to choose between 

 sacrificing the total length of the experiment by prolonging the period 

 of normal diet, or shortening this period so as to obtain extended 

 measurements with restricted diet. The second alternative seemed to 

 us the more desirable; consequently, the values during normal diet 

 for these men were determined on a relatively few days in the latter 

 part of September and during the first few days of October. 



BASAL METABOLISM PRIOR TO DIET RESTRICTION. 



The basal metabolism was measured individually in Springfield 

 by two forms of respiration apparatus: First, a respiratory-valve 

 apparatus employing a mask, Tissot valves, and a carefully calibrated 

 spirometer, with Haldane gas-analysis apparatus for the analysis of 

 the expired air (a combination highly recommended by Dr. T. M. 

 Carpenter); and second, a portable respiration apparatus of new de- 

 sign. These measurements were made only with the men in Squad A 

 and with Ham, one of the men in Squad B. Finally, the metabolism 

 measurements in the group respiration chamber in Boston were, also 

 practically basal. These group measurements were made with both 

 Squads A and B. 



The values obtained with the respiratory-valve apparatus are of the 

 greater significance, particularly for the normal period, for several 

 reasons. In the first place, the apparatus had long been in use and 

 thus was thoroughly tested. The technique had also been carefully 

 developed. The portable respiration apparatus, while thoroughly 



