444 Influence of Inanition on Metabolism. 



There are two causes for the variations in the output of carbon dioxide on 

 the different days of the experiments: first, differences in the body-weights 

 of the subjects, and second, variations in their muscular activity. It is 

 customary, in comparing experiments of this nature, to compute the carbon 

 dioxide production per kilo of body-weight or per square meter of body sur- 

 face. Since these values are given separate treatment later in the report, the 

 table showing the computation is reserved for that discussion, attempt there 

 being made to reduce the carbon dioxide output not only to constant body- 

 weight and body surface, but also during periods of approximately constant 

 bodily activity, namely, during the period of sleep at night. 



relation of carbon in urine to total carbon. 



Carbon is excreted from the body in two forms carbon dioxide of the 

 respiratory gases and the carbon of organic matter of the urine. To these 

 should be added, in experiments in which food is taken, the carbon excreted in 

 the feces, but as explained elsewhere (see p. 120) the feces are not considered 

 in the fasting experiments. For computing the losses of body material during 

 fasting, the amount of carbon in the urine is of importance, and hence the 

 amounts for these experiments have been computed and recorded in table 223. 



The proportion of total carbon excreted in the urine is of interest, since in 

 many of the earlier experiments, the actual amounts of the carbon in the urine 

 have not been determined, the assumption being made that the carbon excreted 

 in this manner is but a small proportion of the total. The per cent of total 

 carbon in the urine is given in the last column of the table. 



The total carbon elimination varies practically with the carbon dioxide 

 production. The smallest excretion found during any fasting day is on the 

 fifth day of experiment No. 73, 139.4 grams; the largest recorded amount is 

 on the second day of experiment No. 82, 220.0 grams. The average daily 

 amount for all experiments is 174.3 grams. 



As was pointed out in a discussion of the quantities of carbon in the urine, 

 there are wide variations in the amounts from day to day, the largest elimina- 

 tion occurring as a rule, in the later days of the fast. This is especially notice- 

 able in the case of experiment No. 77, where as high as 14.6 grams of carbon 

 appeared in the urine on a single day. An examination of the table shows that 

 the carbon of the urine tends to increase as the fast progresses, while the total 

 carbon frequently decreases. Hence, the proportion of total carbon which 

 appears in the urine varies considerably. The lowest per cent is found on the 

 first day of experiment No. 71, namely, 2.8, and the highest on the last day of 

 experiment No. 77, namely, 8.9. The daily average of all experiments without 

 food is 5.5. 



