The gaseous-metabolism measurements of both Squads A and B in the large group respiration chamber are confined exclusively to the carbon-dioxide production. To compute the heat output from these values, it is necessary to assume a respiratory quotient. In the case of Squad A the respiratory quotient on the basal night is very properly assumed to be 0.81. This respiratory quotient was likewise used for Squad B for the night experiments in the respiration chamber prior to diet restriction. With both Squads A and B after the diet restriction respiratory quotients other than the basal must be assumed. These are usually obtained for Squad A from the measurements actually made with the respiratory-valve apparatus on the days nearest to the night in the group respiration chamber. The values must be assumed to apply likewise for Squad B at a corresponding period of weight reduction.

The values obtained for the minimum metabolism during sleep, as measured in the group respiration chamber prior to the period of reduced diet - i. e., the basal values - for both Squads A and B are given in table 114, in which it can be seen that the values for Squad A are confined to the measurements on one night only (September 29-30) while for Squad B we have measurements for five nights. Although this table gives the total body-weight without clothing, total body-surface computed from the height-weight chart, and the total carbon-dioxide per hour, for comparative purposes we must rely solely upon the values given in the last two columns, namely, the heat per hour (computed) on the two bases of per kilogram and per square meter. These present several very interesting points. The average heat production per hour for Squad A was 1.10 calories per kilogram and 40.8 calories per square meter. From the normal values for the heat production per square meter per 24 hours obtained with the respiratory-valve apparatus and given in table 113, it can be computed that the average heat production per square meter per hour for the squad was 39.5 calories. The slightly higher value obtained in the chamber may possibly be explained on the ground that it is not a true post-absorptive value, since the men had supper at 5 o'clock and the minimum metabolism was often found about 2 or 3 o'clock in the morning. To offset this we have the fact that the values were for the most part obtained during deep sleep. The agreement between the two values, 40.8 and 39.5 calories, may be said to be, on the whole, as close as one could expect.

Table 114. - Minimum Metabolism During Sleep As Measured In Group Respiration Chamber Prior To Period Of Reduced Diet

The values found with Squad B are of special interest, for one of the chief reasons for using Squad B throughout this experiment at the expense of a large amount of time and labor, was not only to obtain a basal value for comparison, but to study possible seasonal variations in the various factors measured. As pointed out in an earlier section, when the men returned from their summer vacation, in the latter part of September, they came for the most part from Y.M.C.A. camps and active outdoor work. They immediately began an entirely new routine, living more or less indoors, studying late at night, and sleeping in the college dormitories. If there is, then, a normal seasonal variation in the metabolism, such studies as were made with Squad B would reveal it. The metabolism of Squad B as measured in the group respiration chamber throws considerable light upon this point. On October 6-7 (one week after the normal experiment with Squad A), Squad B showed a heat output per kilogram of body-weight and per square meter of body-surface of 1.10 and 40.5 calories, respectively, this being nearly identical with the values for Squad A normal. One month later, November 3-4, similar values were obtained. It thus appears from these measurements that the values found with Squad A were normal, and also that the number of men in the squad was sufficient to secure an average value. In other words, if Squad A had been twice as large on September 29-30, the heat per square meter and per kilogram per hour would not have altered in the slightest.

The subsequent course of the basal-metabolism measurements with Squad B is also of interest. On November 17-18 there was a fall of approximately 2 per cent in the metabolism. One month later, December 15-16, there was another fall of not far from 2 per cent. Using the values on October 6-7 as a basis, we have a fall in metabolism of about 4 per cent in the heat per kilogram and a little over 2 per cent in the heat per square meter of body-surface. Up to this point, one might reasonably and legitimately state that there was no seasonal variation in metabolism. On the night of January 5-6, prior to the day when the restricted diet was begun with Squad B, a last experiment was made inside the group respiration chamber to obtain the basal value. To our great surprise this showed a very considerable alteration in metabolism. The hourly heat per kilogram dropped to 0.98 calorie and per square meter of body-surface to 36.8 calories. Using the values on October 7 and November 4 as basal values, we find here a fall of approximately 11 per cent in the heat production per kilogram of body-weight and about 9 per cent per square meter of body-surface. Of particular interest in this connection is the fact that these low values were found with Squad B on practically the first day on which they returned from their Christmas vacation. This is in distinct contrast to the values found with Squad A, which showed that both the pulse-rate and, as will subsequently be seen in the general basal-metabolism tables, the metabolism was considerably increased with all the men after returning from their vacation. This low caloric production of Squad B requires a critical examination of the metabolism measurements on this particular night.