QUESTIONS AND SUGGESTIONS 69 



Section 17. 1 . Describe the structure of an ordinary leaf. 2 . What 

 are the largest leaves you have ever noticed ? The smallest ? 3. Do 

 leaves appear before the flowers in spring or the flowers before the 

 leaves ? 4. Do leaves fall off before the fruit ripens or afterwards ? 



5. What plants have you noticed that keep their leaves on all winter ? 



6. Have you noticed any plants whose leaves turn brown in winter 

 but do not fall off? 7. Define petiole, blade, vein, midrib, axil, 

 stomate. 8. Give an example of a kind of leaf which has no 

 petiole ? 9. Have you noticed any striking difference in leaves as 

 to the way in which their veins are arranged ? Describe it. 

 10. Observe the veins in a blade of grass by holding it between 

 you and the light. How are they arranged ? How are the veins 

 of a maple leaf arranged? n. What are some of the plants with 

 which you are familiar whose leaves are used by man for food? 

 For other purposes? 12. What plants and what parts of them are 

 principally used as food for cattle and horses? 13. What tropical 

 plants do you know whose leaves are used by us for food or for 

 other purposes ? 14. Find from an encyclopedia or otherwise from 

 what parts of plants the following plant products are derived: 

 sugar, coffee, quinine, opium, chocolate, manila hemp, olive oil, 

 licorice, peppermint, vanilla, pepper, cinnamon, cloves, cotton, linen, 

 rubber. 15. What things go into living leaves and what things 

 come out of them? 16. Explain the difference between organic 

 and inorganic substances. Give examples. 17. What is meant by 

 the statement that the green parts of plants form "the link between 

 the inorganic and the organic" ? 



Section 18. 1. Is the highest "fulfillment" of the individual in 

 what it does for its own benefit or in what it does for the benefit of 

 the race to which it belongs ? Explain. 2. A sense of physical com- 

 fort results from satisfying hunger. Does any similar sense of com- 

 fort result from aiding others than ourselves ? Have you ever experi- 

 enced it? Have you ever felt a sort of "hunger" to aid others? 

 3. What is meant by asexual reproduction? Give examples of it 

 other than those given in the book. 4. By what process is the embryo 

 of seeds formed ? 5. What are some of the organs of plants that 

 have to do with sex reproduction ? 



Section 19. 1. Write a list of the cultivated plants which you 

 know by their flowers. 2. Write a list of the wild plants which you 



