20 



PHYSIOLOGICAL REGULATIONS 



In the course of time (fig*. 1), water is lost until the initial weight 

 is approximately reattained. The rate at which water is lost in- 

 creases as more is administered, and the whole process of recovery 

 lasts but little longer. For each curve, all tests in which similar 

 amounts of water were initially given contribute values of relative 

 body weight ; all those values occurring in the same serial interval 

 of time are averaged arithmetically. 



Rates of elimination are also averaged arithmetically, though 

 with equal suitability harmonic means might have been used. The 

 rates of elimination (fig. 2) vary with time as well as with the 



12 3 



Hour5 

 Fig. 2. Eate of total water output ( % of Bo/hour) in relation to time after diverse 

 quantities of water (shown in figure 1) are given by stomach tube. Each rate is ob- 

 tained from the change of body weight during 0.25 hour, and the average is plotted at 

 the middle of the period in which it prevailed. 



quantity of water put into the stomach. Initially there is a lag 

 period in which loss is unmodified ; thereafter rates increase quickly 

 to maximal, followed by more gradual fall. With regain of control 

 water content, the rate of water output approaches the initial rate. 



Very similar relations are shown (figs. 3 and 4) by measuring 

 the exchanges through urinary channels alone. Exact comparisons 

 and differences between total losses and urinary losses are not 

 computed, inasmuch as figures 3 and 4 contain added tests that are 

 not represented in figures 1 and 2. 



In this general account of mean results, no account is taken of 



