54 THE NATURE OF LIFE 



a similar fate. Rapid progress is being 

 made in this direction and every fresh 

 discovery strengthens the belief that the 

 whole process may be explained by the 

 laws of chemistry. 



Let us now consider the processes by 

 which food is utilized to furnish energy. 

 This is known as destructive metabolism 

 and consists largely in the combustion 

 of food in the organism (respiration). 



It may be instructive to compare the 

 combustion in the living organism with 

 that in a tallow candle. 



The food which enters the body and 

 is stored, or remains undigested for a 

 time, may be compared to the inactive 

 tallow of the candle. If it is to be used 

 it must first be prepared for absorption. 

 As a rule solids cannot be taken into 

 living cells and the food must be liquefied 

 before it can be absorbed. This is ac- 

 complished by digestion. 



In the candle also the fuel must be 

 liquefied before it can be absorbed. It 

 is then transported to the place where 



