CHAPTER XXVIII 

 HOW FOOD IS USED BY PLANTS 



329. Questions for Discussion. 1. In what sense is chlorophyll 

 sometimes properly called the magician food-maker of the world? 

 2. What is meant wheu we say a modern field of wheat, corn, or oats 

 is man's device for exposing chlorophyll to the light so as to make it 

 do what he wants it to do ? Is there the same meaning in a field of cot- 

 ton? 3. How does the world's food supply depend partly upon the 

 fertility of the soil? 4. When chinch bugs, grasshoppers, or crickets 

 strip the leaves from wheat or oats the desired grain is not produced, 

 no matter how favorable the soil and weather. Why? 5. Is it a public 

 as well as an individual matter for a farmer to allow his farm to be- 

 come poor in its production of crops? 6. How are domestic animals 

 dependent upon chlorophyll work in plants? 7. From the standpoint 

 of the soil fertility why is live-stock farming better than grain farm- 

 ing? 8. Should sewage be turned into streams and thus washed away? 

 Why? 9. In what ways is plant food used to satisfy the needs of the 

 plant itself? 10. Is plant food made and stored in grains, etc. primarily 

 for the good of men who use it? 11. How are plant foods carried 

 about through the plant? 12. What is meant by saying that starch is 

 a storage form of plant food, and sugar a transportation form ? 13. What 

 plants produce most of our foods? 14. Do plants as well as animals 

 carry on processes of assimilation of food and processes of respiration ? 



330. Do plants need food ? People often speak of the food 

 stored in fruits, grains, stems, leaves, and roots as if those 

 foods were made by plants for the purpose of feeding men. 

 That is men's purpose in selecting and cultivating plants, 

 and therefore they strive to cause plants to manufacture 

 large quantities of the kinds of food which they desire. But 

 plants are living things and, as such, must have foods by 

 means of which to grow and to replace used or worn-out 

 parts. Green plants have the power of making their own 



