BASAL METABOLISM. 81 



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 supple- 

 mented 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. 



GENERAL CONCLUSIONS REGARDING 8-HouR EXPERIMENTS IN MIDDLE-TOWN. 



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 pro- 

 duction 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 



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



