184 



PHYSIOLOGICAL KEGULATIONS 



The similarities of time relations among species and tissues, 

 seem remarkable when it is realized that no anatomical arrange- 

 ment is common to all the living units, and certainly no single 

 variety of physical process is concerned in the water exchanges. 

 The fact to be recognized is that the several living units do the 

 same things in nearly the same sequence while recovering from 



o I 2 I ^ 



Hours Hours 



Fig. 106. Tolerance curves for water in six species or tissues; total water load 

 (% of Bo or Vo) in relation to time. All are upon similar scales of coordinates. Dog, 

 from figures 1 and 10; Man, from figures 49 and 56; Frogs in water, from figure 65; 

 Isolated muscle of frog in Kinger's solution from figure 98; Phascolosoma in sea water 

 from figure 85; Plasma of rabbit in situ, following transfusion or hemorrhage, from 

 figure 95. 



water loads, without sharing any other unique property that is 

 recognized to be correlated with maintenance of water content. 



Diversities among the living units studied are materials in the 

 comparative physiology of water exchanges. Being drawn inde- 

 pendently of what organs each species possesses, comparisons are 

 expressed numerically. For instance, I note that a garter snake 



