428 Influence of Inanition on Metabolism. 



gestion of large amounts of water on the water-vapor output of man. The 

 experiments did not include observations during a period of inanition. 



The figures in tables 193 and 218 permit a comparison of the water of 

 respiration and perspiration with the water in the urine, although no ratios 

 between these two factors have been computed and tabulated. As is the case 

 with the water of respiration and perspiration, the water in the urine tends to 

 diminish as the fast progresses, and yet in experiments Nos. 69, 71, and 75 

 the contrary is true. Furthermore, on the second day of experiment No. 73, 

 on which the largest amount of water in the urine (2928 grams) was voided, 

 the total water-vapor output was but 636 grams, while with the same subject 

 on the first day of experiment No. 71, where the water in the urine was about 

 one-third of that on the second day of experiment No. 73, the water of respira- 

 tion and perspiration was more than 100 grams larger. No relation, therefore, 

 appears between the amount of water in the urine and the amount of water- 

 vapor eliminated. 



Influence of the water content of the body. As will be seen from the dis- 

 cussion on page 467, there is material loss of preformed water from the body 

 as the fast progresses, hence it might be contended that the restricted elimina- 

 tion of water-vapor may partly be accounted for by the lowering of the 

 absolute amount of water present in the body. On the other hand, the actual 

 amount of preformed water lost from the body is but a small proportion of the 

 total water in the body and the percentage of water present in the body is 

 hardly affected by the losses in fasts as short as are these under discussion. It 

 does not seem reasonable, therefore, to conclude that the relatively small losses 

 of preformed water from day to day can influence appreciably the diminution 

 in the output of water-vapor noted as the fast progresses. 



Influence of variations in relative humidity. As the air comes in contact 

 with the moistened mucous membrane of the mouth, nose, throat, and lungs, 

 water is rapidly evaporated from these tracts and the exhaled air has com- 

 monly been assumed to be saturated with water-vapor at the temperature of 

 the body. 



Air is inspired at the relative humidity of the air in the chamber. The 

 lower the humidity, the greater the amount of water-vapor taken up by the 

 air, as it passes through the lungs. Similarly, as the air comes in contact 

 with the surface of the body, the lower the humidity the greater the amount 

 of water-vapor taken up. We should then, naturally, expect to find that the 

 amounts of water given off by the body per day would in the majority of 

 instances be affected by the relative humidity of the air, although the influence 

 of the relative humidity of the air might or might not be so great as to 

 obliterate any other factors. 



An examination of the total amount of water remaining in the chamber at 

 the end of each period, as given in the detailed tables in connection with these 



