92 FOOD AND DRINK 



twenty to sixty years of age is the balance exact between 

 loss and gain. (Read Note 1.) 



3. Hunger and Thirst. When the system is deprived of its 

 supply of solid food during a longer time than usual, nature 

 gives warning by the sensation of hunger, to repair the losses 

 that have taken place. This sensation or pain appears to be 

 located in the stomach, but it is really a distress of the system 

 at large. Let a sufficient quantity of nourishment be intro- 

 duced into the system in any other way than by the mouth, 

 and it will appease hunger just as certainly as when taken in 

 the usual manner. 



4. The feeling of thirst, in like manner, is evidence that 

 the system is suffering from the want of water. The apparent 

 seat of the distress of thirst is in the throat; but the injection 

 of water into the blood-vessels is found to quench thirst, and 

 by the immersion of the body in water, the skin will absorb 

 sufficient to satisfy the demands of the system. The length 

 of time that man can exist without food or drink is estimated 

 to be about seven days. If water alone be supplied, life will 



1. The Waste of the Body. "In the physical life of man there is 

 scarcely such a thing as rest the numberless organs and tissues which 

 compose his frame are undergoing perpetual change, and in the exercise 

 of the function of each some part of it is destroyed. Thus, we cannot 

 think, feel or move without wasting some proportion, great or small, 

 according to the energy of the act, of the apparatuses concerned such 

 as brain, nerve or muscles. Now this waste-product cannot remain in 

 its original situation, where it would not only be useless dross, but also 

 obstructive and injurious. Such old material is being daily removed 

 from our bodies to the average amount of three or more pounds; and 

 that an equal quantity of new shall take its place is the first principle of 

 alimentation. To express it in commercial language, the income must be 

 equal to the expenditure ; and in each of us the amount of this exchange 

 must in a lifetime reach many tons. This tissue-change is so complete, 

 that not a particle of our present body will be ours a short time hence ; 

 and we will be, as I have lately seen it phrased, like the knife which, 

 after having had several new blades, and at least one new handle, was 

 still the same old knife to its owner. We are, in fact, constantly * moult- 

 ing. 1 " Mapother's Lectures on Public Health. 



8. System deprived of food ? Warning ? What is the pain ? How proved ? 

 4. Feeling of thirst ? Seat of the pain ? How proved ? Time a person can exist with- 

 out food ? 



