116 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



a minimum of 220 c.c. in July and a maximum of 236 c.c. in Septem- 

 ber; with M. A. M. a minimum of 237 c.c. in December and a maximum 

 of 251 c.c. in March; with H. F. T. a minimum of 184 c.c. in August 

 and a maximum of 205 c.c. in June; while with J. B. T. a minimum 

 was found of 244 c.c. in October and a maximum of 281 c.c. in Decem- 

 ber. It is thus clear that the metabolism of these subjects, as indicated 

 by oxygen measurements alone, does not show regular seasonal vari- 

 ations, but only noticeable differences in averages from month to month. 



Although in table 46 we have recorded only the oxygen measure- 

 ments, yet it is evident that with these normal individuals the respira- 

 tory quotient in the post-absorptive condition remains reasonably 

 uniform at 0.85, so that for purposes of comparison we may assume that 

 the oxygen consumption corresponds to the heat production. While, 

 therefore, the data show somewhat large differences in the metabolism 

 for the different months with different individuals, there is no uniform- 

 ity other than the possible tendency for the high values to fall in the 

 month of March, this occurring with four subjects, and for the minimum 

 metabolism to fall in July, as also found with four subjects; but the 

 results are not sufficiently uniform to draw definite conclusions as to the 

 maximum and minimum metabolism occurring in these two months. 



The possible fluctuations in the metabolism have likewise been shown 

 for 35 subjects 1 who were studied for periods of time varying from 5 

 days to 4 years and 5 months. In all cases the subjects were in the 

 post-absorptive condition and with complete muscular repose. The 

 increase in the oxygen consumption is used as an index of the fluctua- 

 tions of the metabolism, with the value for the minimum daily average 

 as a basis. The figures indicate that the oxygen consumption varied 

 above the minimum from 3.5 per cent to 31.3 per cent, with an average 

 variation of 13.9 per cent. The greatest variations were found as a 

 rule with those subjects studied for the longer periods. 



The results obtained with many of these subjects were considered in 

 more detail in the preceding section. By reference to tables 37 to 45 

 it will be seen that while the average values showed usually no tendency 

 to change materially during the months or years the subjects were 

 studied, yet the values for the individual periods often fluctuated 

 widely. With such fluctuations it would not be logical to use a basal 

 metabolism determined on one day for comparison with the metabolism 

 determined on another day, except possibly when the superimposed 

 factor to be measured is of considerable size, as in severe muscular work. 



With well-trained subjects of long experience, an average basal value 

 may be considered as more reliable than those obtained with untrained 

 subjects. Perhaps one of the best illustrations of the constancy of 

 metabolism with a thoroughly well trained subject is that of the pro- 

 fessional bicycle rider, M. A. M., studied by Benedict and Cathcart, 2 



'Benedict, Journ. Biol. Them., 1915, 20, p. 263, table -1. 

 2 Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 1*7, 1913. 



