420 Influence of Inanition on Metabolism. 



WATER OUTPUT. 



No other compound exists in the body in such large proportions as does 

 water. The fluctuations in the amount of water in the body during inanition, 

 therefore, demand special study. During fasting experiments as ordinarily 

 conducted, drinking-water is allowed, and hence the relations between the 

 amounts of drinking-water and the amounts of water excreted either through 

 the kidneys or lungs and skin are likewise of importance. 



In discussing the volume of urine during fasting, considerable emphasis was 

 laid upon the relation between the amount of water consumed and the volume 

 of urine, and specifically the water in urine. 96 It was there pointed out that 

 while, in general, the ingestion of large volumes of water was accompanied by 

 large volumes of water in the urine, at the same time there were marked 

 exceptions to this general rule. These exceptions imply that the water of urine 

 is an excretory product governed by definite laws, the nature of which is as 

 yet but little understood. Since, in nearly all experiments heretofore made 

 with fasting men, an accurate measure of the total water excretion is lacking, 

 the data obtained in these experiments will, it is hoped, be of value in explaining 

 the nature of the apportionment to the kidneys, lungs, and skin of the water 

 excreted by the body. 



Since drinking-water was allowed ad libitum in all the experiments here 

 reported, the actual loss of water to the body was less than the loss occurring 

 during complete abstinence from water as well as food. 



The amounts of drinking-water consumed by the various subjects were 

 widely different in different experiments. In certain experiments, the subjects 

 were especially requested to consume large quantities of water, but in the 

 series of 2-day fasting experiments, the subjects as a rule consumed only as 

 much as was actually desired, the amount taken rarely exceeding 1000 grams. 

 On one day but 115.1 grams were consumed. The data for the amounts of 

 water consumed are given in table 193. 



While under ordinary conditions when food is eaten, some water may be 

 furnished the tissues by the oxidation of the organic hydrogen of the food, 

 in fasting experiments where no food is ingested the water of oxidation of 

 organic hydrogen must be formed from the organic hydrogen of the body 

 material broken down. The proportions of water thus formed may be more 

 properly studied after the consideration of the katabolism of body material. 

 Thus, it is important to recognize that while the water output consists for the 

 most part of preformed water, varying amounts resulting from the oxidation 

 of organic hydrogen are present in the water excreted. 



Excretion of water from the body may take place in three ways ; through the 

 lungs and skin, i. e., water of respiration and perspiration ; through the urine ; 

 and through the feces. 



M For discussion of the relation of the water in urine to water consumed, see page 

 348 and table 193 (p. 355). 



