METABOLISM AND FOOD 101 



pigs take 7-8, cows 4-6, oxen 4-5, and horses 2-3 

 kilos of water. Naturally the surrounding tem- 

 perature has a considerable influence on these 

 quantities, for the heat of the body is lowered in 

 hot weather by evaporation of water from the 

 surface of the skin. In cold weather or in cold 

 surroundings the evaporation of water is much 

 reduced. 



If the amount of water consumed is continually 

 above that which is necessary, then the tissues 

 become of a soft, flabby nature owing to the storage 

 of fluid in them ; animals in this condition are less 

 resistant to injurious influences or disease. Further, 

 when the body is over-supplied with water, the 

 food is not so well utilised owing to the digestive 

 juices being too dilute (see Chap. VI), and it is also 

 found that the metabolism of the food is increased 

 by an excessive supply of water. The water con- 

 tained in green fodder, roots, tubers, etc., the so- 

 called water of vegetation, is said curiously enough 

 to exercise a favourable influence upon the con- 

 sumption of protein. It has been observed that 

 the protein of green foods causes more increase of 

 tissue than does the protein of hay, which may have 

 been prepared from the same plants without loss. 

 These differences may perhaps, however, only be 

 due to the fact that mastication of the green food 

 involves less work than for the hay, which would 

 leave more protein for the production of flesh. 



