262 WATER ITS RELATION TO METABOLISM 



transferred through the living skin of the frog from without 

 inwards. The converse holds good for dead skin. A small dose 

 of alcohol increases and chloroform depresses the rate of transfer- 

 ence. He found that the transference took place when an isotonic 

 solution (-6 per cent. NaCl) was placed on either side of the skin 

 and at the same pressure. In this case neither our conception 

 of the processes of nitration nor of osmosis is adequate to explain 

 the transference. 



In its relation to metabolism, water differs from other food- 

 stuffs in that it does not become stored in the body if taken 

 in excessive amount. An enormous consumption of water only 

 lessens for a few hours the osmotic pressure or solid content of 

 the blood, and by the adjustment of excretion both the blood and 

 the tissues steadfastly retain their normal percentage of water. 

 A melancholic took 7 litres of water a day " to purify his blood," 

 and yet the percentage of haemoglobin in his blood remained 

 unaltered. The energy spent on excreting water must be very 

 little, since neither the C0 2 output of a fasting cat was found 

 increased by giving it much water, nor was the 2 intake of a 

 child influenced by an attack of diabetes insipidus during which 

 she drank 8 litres of water a day. 1 



The taking of water with food neither slows digestion nor 

 hinders absorption. Water does not appear to be absorbed by 

 the stomach, and escapes into the intestine at the rate of about 

 one pint in three-quarters of an hour. The nature of the diet 

 influences the amount of water taken, for proteid food occasions 

 diuresis. Thus with a diet of 500 grm. meat and 200 grm. 

 starch, 650 grm. of water were taken, while with a diet of 1500 

 grm. meat, 1238 grm. of water were taken. Peschel, seeking to 

 accustom himself to a very low proteid diet, found he diminished 

 his water intake from 1300 to 620 c.c. 



The taking of large amounts of water provokes diuresis and 

 increases the N 2 output. Exact observation conducted for 24 days 

 on man shows that the water only washes out the urea stored in 

 the tissues, and does not provoke increased destruction of tissue 

 proteid. This influence is the greater, the greater the concentra- 



1 There is possibly an error in this observation, for the warming of this 

 amount of water from 12 C. to body temperature must have required 200 Cal., 

 which was 13 per cent, of the total worth in Calories of the diet taken by the 

 child (von Noorden). 



