52 MAN, THE ANIMAL 



energy from the food eaten. This simple state- 

 ment fails to convey anything of the complexity of 

 the problem or the steps in the process that still 

 remain unknown. It is an easy matter to write 

 the word energy, but what do we really mean by 

 It? 



Ever since Huxley taught biology In the Royal 

 School of Mines, teachers have been using his il- 

 lustration as an introduction to this theme. It Is 

 the familiar one of the steam and coal. 



When coal is burned in the firebox of the engine, 

 heat is given off that transforms the water into 

 steam. This steam is used to move the engine. 

 Smoke, ashes, and some heat are the wastes in 

 this process. Locked up within the coal, there is 

 an amount of energy that can be accurately com- 

 puted. No mechanical device has yet been con- 

 structed that is able to utilize all of this energy. 

 There Is always a varying amount of waste. 



Here Huxley's comparison must cease, as fur- 

 ther analysis reveals that there is no real similarity 

 between an engine and a living animal, not even 

 in the manner in which they utilize energy and 

 do work. The illustration however, helps one to 

 see one aspect of the problem — an aspect that is 

 necessary in a scientific discussion. 



The grain and hay fed to a horse are utilized by 

 the horse and there Is a noticeable amount of 

 waste. As a result of this feeding, the horse is 



