THE MAMMALS 145 



cent. After a single large drink, diuresis starts as soon 

 as the water begins to be absorbed from the intestinal 

 tract, reaches its maximiun in 30 minutes, and within an 

 hour or so the body is back in water balance. It is, how- 

 ever, possible to drink water faster than the kidney can 

 excrete it. Because of the division of water reabsorption 

 between the proximal and distal systems, the urine flow 

 cannot exceed the fraction (15 per cent) of the glomeru- 

 lar filtrate that is delivered from the proximal to the 

 distal system: meaning, in an average man with a fil- 

 tration rate of 125 cc. per minute, roughly 20 cc. per 

 minute or 27 hters (7 gallons) per day. Record beer 

 drinkers consume from 15 to 20 bottles (5.4 to 7.2 hters) 

 in 3 hours (which works out at 30 to 40 cc. per minute) 

 but they end the evening excessively hydrated, that is 

 to say nearly half the water i5 still in the body when the 

 bar closes. 



Alcohol, which exerts an inhibitory action in the cen- 

 tral nervous system generally, also inhibits the secretion 

 of ADH, and consequently when taken in concentrated 

 form it increases water excretion, the effect (in physio- 

 logical doses) being such that 1 cc. of alcohol causes 

 the excretion of approximately 10 cc. of water. Beer con- 

 taining 4.6 per cent of alcohol is not dehydrating since 

 an excess of water over alcohol is ingested. Straight 

 whiskey, however, with 40 to 45 per cent alcohol, is 

 dehydrating, and consequently it will not serve to 

 quench a man's thirst, for which purpose it must be 

 diluted with water at least one to four. 



If water were always freely available, urea and other 

 waste products could readily be excreted either in the 

 dilute urine characteristic of water diuresis or in more 

 concentrated urine formed during the dehydrated or 

 hydropenic {hydro = water; penia = poverty) state, even 

 though in the latter instance the osmotic concentration 

 of the urine did not exceed that of the blood. But water 

 is not always freely available, nor has it always been 



