492 Influence of Inanition on Metabolism. 



computation from the amounts of nitrogen and carbon known to be contained 

 in the urine. In these experiments not only was the amount of energy 

 determined but also the nitrogen and carbon and organic matter, so that we 

 have the means for determining the ratio of the heat of combustion to the nitro- 

 gen, carbon, and organic matter. These ratios have been calculated and are 

 given in the following table. The results are expressed in terms of the number 

 of calories of energy which accompany 1 gram of nitrogen, carbon, and organic 

 matter, respectively. 



Thus, on the first day of experiment No. 77, for every gram of nitrogen in 

 the urine, there was found to be 10.216 calories of energy. For every gram 

 of carbon there were on this day 11.292 calories, and for every gram of organic 

 matter, 3.184 calories. An inspection of these ratios shows that the ratio of 

 energy to nitrogen may vary considerably. The lowest ratio observed is on 

 the third day of experiment No. 59, 7.490, and the highest is that observed on 

 the fourth day of experiment No. 77, 14.847. The average ratio is not far 

 from 9. In the nitrogen metabolism experiments, the heat of combustion of 

 the urine was determined on 6 days. The respective ratios of the heat of com- 

 bustion to nitrogen were 8.8, 11.0, 9.6, 9.3, 8.3, and 9.8, respectively. 



The ratio of energy to carbon is much more nearly constant, the lowest ratio 

 (9.436) observed being on the first day of experiment No. 68 and the highest 

 on the first day of experiment No. 85 (12.468). Here the differences are 

 very much less than in the case of the energy-nitrogen ratio and it is fair to 

 assume that in experiments of this character for every gram of carbon in the 

 urine there are not far from 11.5 calories of energy. 



The determination of carbon in the urine is, however, not much less trouble- 

 some than the determination of energy and this ratio is, therefore, not of 

 especial value, although it is unusually constant. Since the carbon is in large 

 measure proportional to the total organic matter, the ratio of heat of combus- 

 tion to organic matter is of interest since the organic matter can be determined 

 with little difficulty. These ratios have been computed and are recorded in 

 table 237. They show that for every gram of organic matter there may be 

 energy corresponding to from 2.264 to 3.857 calories, but in a large majority of 

 instances, the ratio is not far from 3.2. While by no means as constant as 

 the energy-carbon ratio, the energy-organic matter ratio is much more satis- 

 factory than that based upon the determination of nitrogen. In practically 

 all of the experiments here reported, the use of the factor 3.2 as the ratio of 

 energy to organic mattter would have given results which would not have 

 seriously affected the final computations. It is of especial importance, how- 

 ever, to note that in these determinations the total transformations of energy 

 were extremely small and consequently in ordinary metabolism experiments 

 where the energy transformations are larger the total energy in the urine 

 may be computed from the organic matter and the results be well within the 

 limits of error. 



