The average basal metabolism for each subject is recorded in table 27, in which are given the average values for the body-weight, the carbon dioxide produced, oxygen consumed, heat produced, and nitrogen excreted in the urine per 2-hour period. The nitrogen values are included in this table as an indication of the probable protein katabo-lism in the experiments. In no instance was the diet controlled prior to the experiment, although usually no food had been taken for at least 12 hours. These average nitrogen values are also shown in table 28, together with all of the available nitrogen values for the individual experiments included in tables 23, 24, 25, and 26. For the subjects A. L. L., A. H. M., H. C. K., and H. R. D., these values are supplemented by other values drawn from experiments not discussed in this publication. The detailed results in table 28 show, particularly with H. R. D. and A. L. L., a much wider variation than would normally be expected. Thus on the second day with H. R. D. April 4,1906, the nitrogen excreted was less than half that excreted on December 5-6,1905. A still more striking variation is that on April 6, 1906, with A. L. L., which is approximately one-third of that found on April 27, 1904, with the same subject. In general the variations from the average value are not sufficiently great to affect seriously the computations of the energy transformations in which it is desirable to apportion the energy between the protein and the other constituents of the metabolism.

Table 26. - Basal Metabolism At Different Times Of Day In Calorimeter Experiments, Subject* In Sitting Position. Middletown

(Values per 2 hours).

1The beginning of the "First two hours" was for the subjects in this table between 8h05m a. m. and 9h05ma. m. 2Heat eliminated corrected for change in body-weight but not for change in body-temperature.

Table 27. - Summary Of Average Values For Basal Metabolism Determined For Subjects In Sitting Position In Calorimeter Experiments. - Middletown

(Amounts per 2 hours).

1Includes all nitrogen values obtained with these subjects for the periods in which the basal metabolism was determined and on any first day of fasting. See table 28. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature.

Table 28. - Nitrogen Excreted In Urine During Experiments Without Food

(Amounts per 2 hours).

1Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907. Excepting the results with A. L. L. April 27 and Dec. 16, 1904, these values taken from Pub. No. 77 represent the 24 hours of the first fasting day.

2Determined in 24 hours of first day of fast.

General Conclusions Regarding 8-Hour Experiments In Middletown

The general conclusion may thus be drawn, from an inspection of the data in tables 23,24,25, and 26, that for the first four 2-hour periods in the daytime, beginning at approximately 9 o'clock, with the subject in the post-absorptive condition, there is usually a somewhat high value in the first period of the day, followed by a reasonable constancy in the next three periods; in the few values recorded for the fifth and sixth periods, a tendency is shown for the metabolism to decrease with two subjects and to increase with a third subject. There is, of course, a possibility that the increases noted in some of the values during the later periods were due to restlessness of the subject as a result of the long sojourn in the chamber. On the other hand, there was certainly no external muscular activity of sufficient moment which would justify us in assuming that the measurement of the metabolism was vitiated in this way.

In using the data for basal values in the measurement of the influence of the ingestion of food, it is evident that when major increments are to be expected one may disregard the slight variations noted throughout the day in these tables and consider that the metabolism is essentially constant. This is in line with the earlier interpretation of basal values given by us in a previous publication,1 which were obtained in duplicate experiments during the daytime, but occasionally during the sleeping period. A close agreement was there noted in the average values for the carbon-dioxide production, oxygen consumption, and heat production for the experiments compared. It should be remembered, however, that the average values referred to were for fairly long periods, i. e., from 6 to 12 hours, and in at least one instance, for 4 days. While these values do indicate, therefore, a constancy in the metabolism for periods of this length, they give no evidence as to the possibilities of variations from period to period, such as those shown in tables 23, 24, 25, and 26.

1Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 126, 1910, p. 107, table 45.

In considering the values for the metabolism given in these basal tables, it should be remembered that the subjects were allowed the restricted freedom of the respiration chamber. It was impossible to require them to remain absolutely quiet or to assume a definite position for the period of 8 to 12 hours during which they were under observation. The muscular activity was kept at a minimum, however, and every attempt was made to have it uniform from day to day. While we believe that the values given represent a higher metabolism than the strictly basal metabolism of the individuals studied - i. e., the metabolism with muscular repose and without food in the stomach - we feel that our use of them for comparison with the results of the subsequent food experiments is permissible, in the absence of less contaminated data, inasmuch as the routine and degree of muscular activity on the food days were very similar to those on the days when the basal metabolism was obtained.