446 Influence of Inanition on Metabolism. 



The errors involved in the determination of carbon in the urine have been 

 discussed previously, and even if a gross error of 5 per cent be assumed, the 

 effect on the total carbon excretion is seen to be extremely small, and hence 

 it is obvious that considerable errors in the determination of the carbon in 

 the urine are practically without effect on the total carbon elimination in ordi- 

 nary metabolism experiments. 



Carbon in the urine, feces, and respiratory products was determined in the 

 5-day fasting experiment with J. A. (9). There were found 8.0, 8.3, 9.9, 

 10.3, and 9.3 grams of carbon in the urine, while the corresponding amounts 

 of carbon in the respiration were 188.5, 179.4, 172.2, 169.4, and 165.8 grams. 

 Computed on the basis of the total carbon elimination, the percentages of 

 carbon in the urine for the 5 days were 4.1, 4.5, 5.4, 5.7, and 5.3, respectively. 



The general conclusion can, therefore, be made that with fasting man at 

 rest, the carbon of the urine is about 5 per cent of the total carbon excretion. 



OXYGEN CONSUMPTION. 



Since the classic experiments of Lavoisier showing the relation between 

 oxygen consumption and vital processes, the direct measurement of oxygen in 

 the respiratory gases has not been attempted, save in one or two cases. 

 Although as Lusk 1S0 points out there is no record of the method employed by 

 Lavoisier in obtaining his results, it is remarkable how closely his statements 

 of the quantities of oxygen consumed by resting man agree with the measure- 

 ments by modern methods. 



In the earlier experiments with the Pettenkofer respiration apparatus, in 

 which the attempt was made to determine accurately the water vaporized, 

 estimations of the amount of oxygen were attempted by computations based on 

 the gains or losses of body weight, carbon dioxide excretion, and water-vapor 

 elimination. When the errors involved in the determination of water-vapor 

 are taken into consideration, it is seen that whatever approach to accuracy the 

 oxygen estimations appear to have, it must have been the resultant of a num- 

 ber of more or less compensating errors. 



An attempt was made in the more accurate experiments of Sadovyen (2), 

 in which the amounts of carbon dioxide and water-vapor were determined for a 

 great part of each day, to measure by the indirect method the amount of 

 oxygen consumed. On the 2 days of the fasting experiment with man in 

 which no water was consumed, the oxygen intake was estimated to be 1081 

 and 1010 grams, respectively. The oxygen consumption during the 4-day 

 experiment, in which water but no food was taken, was estimated to be 746, 

 921, 698, and 943 grams for the different days. 



Similarly Likhachev m estimated indirectly the amount of oxygen consumed 

 during a 1-day fast to be 596 grams, or 11.9 grams per kilo of body-weight, 



50 Elements of the Science of Nutrition, Philadelphia (1906), p. 18. 

 ul Loc. cit. 



