30 



PHYSIOLOGICAL KEGULATIONS 



rates of drinking, maximal drafts, frequency of gulps; these and 

 many more are characteristic, and may be observed and correlated 

 in the same detail as the diverse excretory activities. The multi- 

 plicity of the tabulated features is a reminder of the interrelation 

 of processes in water intake. 



Throughout the period of water privation the losses of water 

 (fig. 12) reduced below those prevailing in water balance. 



are 



TABLE 1 



Features of water intake of dogs. The measurements are means, o'bserved unless other- 

 wise noted among 4 individuals that received with their food aiout half 

 of the water gained; while being studied in other respects 

 (Adolph, 'S9, p. 77) 



Both urinary water and evaporated water are economized, the 

 latter but slightly. The dog's "water minimum" is the rate of 

 total water output at a water load of AW — 4 or less ; it is about 

 0.17% of Bo/hour in the dogs studied. 



What conditions prevailed in the above tests of compensatory 

 processes'? Specifications for measurements of water exchanges 

 in dogs are : (i) materials are made available and means are made 

 available for the recovery or attempt at recovery of the animal 

 toward its control state; {2) It is usually desirable that during the 

 actual recovery other substances (food) than water are not avail- 

 able; (5) Total exchanges of water are measured by differences of 

 body weight, and not merely those exchanges by paths that can be 

 identified separately; (4) No anesthesia nor immediate operative 



