260 WATER ITS RELATION TO METABOLISM 



The water lost per diem under the usual atmospheric condi- 

 tions of temperature and humidity is : 



Under conditions of rest and ) , 



hunger f 1-25 per cent, of body weight. 



Under conditions of rest and | 



, . > I ' o 2t . , ,, ., 



average diet j 



Under conditions of rest and ) 

 rich diet I 



Hard work and average diet 2-91 ,, 



In the height of a hot summer day man may lose water at the 

 rate of 4-87 per cent, of the body weight (calculated for twenty- 

 four hours), and if he works hard, at the rate of I'll per cent. 

 (Rubner). A hot day and hard work may increase the rate of 

 water output no less than six times. 



The total water in a man's body is equivalent to the amount 

 normally excreted in fifty to sixty days. 



While frogs can bear drying at a low temperature where 

 their metabolism is at a minimum until their muscles contain 

 in place of 79 per cent, water only 18-28 per cent., man cannot 

 lose more than about 10 per cent, of his body water and live. 



The immediate effect of drying is thirst, a sensation which arises 

 from the lessened percentage of water in the palate and pharynx. 

 The cholera patient thirsts because he loses water from his gut, the 

 diabetic from his kidneys, the labourer from the sweat of his brow, 

 the orator from the local drying of his throat. Thirst results no 

 less from the loss of blood than from the taking of a dose of salts. 



Straube found that dogs could be fed on raw meat and live 

 without taking more water than that in the meat. On the other 

 hand, he could not feed a dog on dry meat powder and fat for more 

 than four days. The body of the animal lost 10 per cent, of its 

 water on this diet, the muscles losing most, viz. 20 per cent. 

 There occurred increased destruction of tissue proteid indicated by 

 a rise in the output of N 2 and P 2 5 . The hind limbs of dogs so 

 reduced showed signs of paresis and a tendency to convulsions, 

 which were immediately set aside by the giving of water. The 

 excretion of water from the skin and lungs diminished with the 

 increased dryness of the body. 



In the case of a man who reduced his water intake by 27 per 

 cent., the blood temporarily became more concentrated, the solids 



