WATER RELATIONS OF MAN 93 



While augmented excretion is proceeding in the presence of 

 water excess, the opportunity to drink water is consistently re- 

 fused. The only known accession of water is the slow formation 

 by oxidations; its rate is uninfluenced by water excess (Carpenter 

 and Fox, '30). 



In general, the rates of elimination of excess water by man are 

 smaller than by dog (relative to body weight), and are slower in 

 accelerating. Eates are less nearly proportional to loads. The 

 amounts of water returned in diuresis are in both species less by 

 an absolute volume than the amounts administered. It may be 

 stated that after water excess the total water losses do not differ 

 significantly from the urinary water losses. 



§ 28. Repeated ingestions by mouth 



What happens when the accession of water to the body con- 

 tinues? Water is ingested in 8 to 16 equal portions at intervals 

 of 0.25 hour (Kingsley and Adolph, new data). Latent periods for 

 appearance of diuresis vary widely, being very long at small rates 

 of ingestion. Times required to reach maximal rates of diuretic 

 response also are diverse in much the same proportion. Ulti- 

 mately stationary rates of elimination of water are attained ; and 

 at some rates of ingestion a steady state of content also is main- 

 tained for an hour or more. In these tests the three factors of 

 intake, output, and load are physiologically fixed with relation to 

 one another. Even in moderate loads the rate at which the body 

 excretes water appears to reach a limit (figs. 54 and 55). But 

 temporarily at least this rate of excretion may exceed the rate of 

 intake (Wendt, 1876). 



Velocity quotients (1/At) in steady states of ingestion and load 

 resemble those that prevail during decreasing rates of water ex- 

 cretion after single ingestion, if compared at equal loads. The 

 quotients decrease with load, whether the loads be total or sensible, 

 and whether the rates of exchange be total or urinary. 



After ingestion of water ceases, rates of elimination gradually 

 decrease, with diverse periods of persistence and diverse decelera- 

 tions. After those states have prevailed in which elimination rates 

 equal ingestion rates, cessation of diuresis requires less time than 

 attainment of its maximal rate does. But where ingestion rates 

 are very high, some hours may be consumed in completing the 



