IX. THE POWER OR ENERGY OF THE 

 PLANT 



218. Enercjij in the jjlant. — In the preceding 

 paragraphs the plant has been shown to do a great 

 many kinds of work, and to use great force or 

 power in carrying out these processes. The push- 

 ing of roots through the soil, the movements of 

 these and other organs, the lifting of the food from 

 the soil to the top of the stems, the pumping of 

 the water from the roots to the leaves, — a distance 

 which may be as great as five hundred feet, — are 

 examples of external forms of work done by the 

 plant. The living plant is only a machine, and it 

 cannot originate or give rise to energy any more 

 than a steam engine may. The engine is simply 

 a device for using the energy released when fuel 

 is burned in its furnaces. This energy in the form 

 of heat converts water into steam, and it may be 

 conducted through pipes and made to act in a man- 

 ner convenient to the operator. 



219. Sources of energy. — The plant receives en- 

 ergy from sunlight, and from the chemical com- 



182 



