20 CHARLES F. W. MC CLURE 



tinned. The principle involved is purely mechanical. We 

 know that when normal frogs are placed in water at any 

 temperature within the range of that of their natural environ- 

 ment, a balance is soon established in the body between the 

 incoming and outgoing flow of water, so that free water in 

 excess of normal does not accumulate in the body. Further- 

 more, we know that the rate at which water is transported 

 through the integument into the subcutaneous lymph sinuses 

 increases with the temperature, so that more water enters 

 the sinuses at high than at low temperatures. This has 

 been demonstrated in table 1, in which is shown the behavior 

 of those frogs and toads whose ureters have been ligated 

 when placed in water at different temperatures. If the ure- 

 ters of these same frogs and toads had not been ligated, any 

 increase in the amount of water entering the body at the 

 higher temperatures would have been almost simultaneously 

 excreted by the kidneys, and a normal balance would thereby 

 have been established between the incoming and outgoing 

 flow of water. This still further emphasizes the fact, main- 

 tained also by others, that the kidneys serve chiefly as passive 

 agents in the sense that they do not seek water, but excrete 

 only that amount made available to them through the agency 

 of the vascular system. If at higher temperatures the in- 

 creased amount of water entering the subcutaneous lymph 

 sinuses through the integument is, through the agency of the 

 vascular system, almost simultaneously excreted by the kid- 

 neys, it is evident that the rate at which this free water is 

 supplied to the kidneys is correspondingly accelerated. If 

 this were not the case, free water would gradually accumu- 

 late in the body in excess of normal, for the reason that less 

 water would then be able to reach the kidneys than was 

 simultaneously being transported through the integument 

 into the subcutaneous lymph sinuses. The question therefore 

 arises whether it would be possible by gradually raising the 

 temperature of the water to reach a point at which, within 

 a given time, more water actually entered the body than could 

 simultaneously be conveyed to the renal circulation for ex- 



