8 The Feeding of Animals 



Plant life not only builds tissue: it stores energy, 

 as we may easily discover. The farmer's boy learns 

 this when he feels the hot glow of the fire that is 

 fed by forest wood. The wood disappears, but he is 

 warmed by the radiant energy. It has occurred that 

 when fuel was scarce and costly and grain was abun- 

 dant and cheap, the western farmer has burned his 

 corn. All he realized in this case for his labor was 

 the warmth which was necessary to make himself and 

 family comfortable. As with the wood, the materials 

 which were collected from the soil and air have been dis- 

 persed in invisible forms during the combustion which 

 liberated the heat energy, except a small heap of ashes 

 on the hearth. The farmers who raised corn for fuel 

 were no richer in storehouse or in pocket. They had 

 simply used an available supply of heat, derived from 

 the energy which was stored in the plant during its 

 growth. , 



But ordinarily, grass and grain are produced, not 

 for fuel but for food purposes, and in this use of vege- 

 table matter we come in contact with a set of phe- 

 nomena equally complex and equally important and 

 interesting to those of its growth. The calf of to-day 

 weighing, perhaps, a hundred pounds, becomes in a few 

 years the immense bullock. What is the source of 

 this mass of bone and flesh ? It is merely plant sub- 

 stance which in other combinations was collected from 

 soil and air. This animal eats his daily ration and 

 makes his daily gain of tissue. When his food is with- 

 held, his body wastes and he dies. If his food varies 

 in amount, his growth is somewhat proportional to the 



