184 THE WONDERFUL HOUSE THAT JACK HAS 



at least two-thirds of the human body is water. Blood 

 is nearly four-fifths water, and flesh, cartilage, and 

 even bone, all have a share. In fact, if all the water 

 were to be pressed out of the tissues of a healthy 

 person weighing one hundred twenty pounds, the 

 substances remaining would not altogether amount 

 to more than forty pounds. 



As the body is continually giving out water through 

 the skin, lungs, and kidneys, it must frequently receive 

 a new supply to keep up the normal proportion of 

 two-thirds. A dry, parched feeling in the mouth 

 and throat is a warning that the proportion of moisture 

 has been reduced below the normal amount, and that 

 the loss must be supplied if we are to feel comfortable. 

 From our study of foods, we know that bread, meat, 

 and vegetables all contain water, and that a part of 

 the body's need for this fluid is supplied by them. 

 The various liquids drunk during the day furnish the 

 remainder. 



Why are we, as a rule, thirsty so much more often 

 in summer than in winter ? Simply because the greater 

 amount of water lost in perspiration must be supplied. 

 For a similar reason, we drink more freely when work- 

 ing or exercising than at times of slight activity. 

 At night there is normally the least craving for water, 

 because the body, being in a state of rest, loses but 

 a small amount through the pores of the skin. 



But water performs other important services in 

 Jack's House. We know that it is used to soak up 



