2O FARM DEVELOPMENT 



dark will grow only while the food material lasts which 

 is stored in the parent seeds or roots. 



The work done by these chlorophyll bodies in the 

 leaves, aided by the sunlight, is very important. The 

 leaves of plants are very complex workshops, or labora- 

 tories, and here the substances taken from the soil and 

 air by the plant are brought together, and by the action 

 of the sunlight on these in connection with the chloro- 

 phyll bodies, the plant chemical compounds are manu- 

 factured. This process is not fully understood, but we 

 may liken these compounds of which the plant is com- 

 posed to " storage batteries." They contain a definite 

 amount of force which can be liberated and used. When 

 plants are burned, the heat produced comes from these 

 "storage batteries," or compounds. Upon burning, the 

 substances coming from the air return to the air in the 

 form of a gas called carbonic acid gas (CO 2 ) ; another 

 small portion of the plant called mineral, which the plant 

 secured from the soil, is left as ashes. Water in the 

 plant is also changed, upon burning, to the gas we call 

 watery vapor. 



The force or energy we see operating in the world has 

 its origin in the sun. Plants are able to absorb from the 

 sun's rays some of this force and store it in latent form 

 in the compounds of which they are made up. Animals 

 eat plants, and their digestive organs in breaking up 

 some of the storage batteries, are capable of setting free 

 some of this force, and we see the result in the work 

 they do, and in the warmth of their bodies. They trans- 

 form some of the plant compound into animal compound, 

 and these, retaining the sun force stored up in the plant 

 compounds, become animal storage batteries. Animals are 

 not capable of making the compounds that they need from 

 the elements in the air and soil, nor of storing up force 

 from the sun. They must depend entirely on plants, or 

 in case of carnivorous animals, on animals which have 



