The Food of Plants 



47 



The green plants can, 

 therefore, build their 

 sugar, fats, and proteins 

 from substances which 

 they take from the soil 

 and air. They can build 

 vitamins also, which it is 

 believed an animal can- 

 not do. So the green 

 plants build out of sim- 

 ple materials all the 

 complex foods used by 

 the living matter of both 

 plant and animal cells. 1 

 Plants can live without 

 animals, but every ani- 

 mal is dependent on 

 plants for the food that 

 keeps it alive. 



The manufacture of 

 sugar. The first com- 



FiG. 33. Without eating, the corn plant 

 has lived, reached its full size, and at the 



plete step in the manu- end of its life has a sur P lus of food which 



it has stored in the ear. 



facture of food by the 



plant is the making of sugar. When light falls on 

 the chlorophyll, carbon dioxid and water are combined 

 within the cells to make sugar. This process is called 

 photosynthesis (Greek, photos, meaning light, and syn- 

 thesis, meaning a putting together). Photosynthesis 



1 Plants also build wood, cork, gums, waxes, and all the various other 

 substances (excepting minerals) found in them. 



