FEEDING METHODS. 373 



of animals and plants which is combustible is 

 made up of these four elements; that which 

 is incombustible which in chemical analysis 

 forms what is called "ash" is made up of a 

 variety of elements, among which may be 

 enumerated: sulphur, phosphorus, potassium, 

 sodium, iron, chlorine, magnesium, bromine 

 and iodine. These incombustible elements vary 

 greatly in quantity in different parts of the ani- 

 mal organism, and as a whole constitute but a 

 small part of the body. 



The largest constituent of animal bodies is 

 water, which is made up of oxygen and hydro- 

 gen in the proportion of two parts of hydrogen 

 to one of oxygen. The per cent of water in 

 any given animal varies with the individual; 

 and also in the individual according as it is fat 

 or lean, a very fat animal containing a smaller 

 proportion of water than a lean one. The 

 amount of water ranges from about thirty-five 

 to seventy per cent. The remainder of the 

 body consists of solid matter of various sorts. 



Now life is simply a burning up of the ani- 

 mal body. Oxygen is taken in through the 

 lungs, is carried by the blood throughout the sys- 

 tem, and combines with other elements in the 

 body just as the materials of a candle do when 

 it is burned. Constant supplies must be kept 

 up, therefore, to replace the parts burned up or 

 the animal will be consumed; that is, will die 



