8o The Great World's Farm 



4. What prevents the moisture from leaving plants too 

 rapidly? 



5. What is the difference between evaporation and trans- 

 piration? 



6. What conditions affect the number of leaf-pores? 



7. Give some idea of the number and size of the pores 

 in a leaf. 



8. What is the nature of the coating or "bloom" of leaves? 



9. Show how the acacia, eucalyptus and cactus adapt them- 

 selves to the climate. 



10. How is this true of plants in temperate climates? 



11. Why is a pine forest less cool than one of "leaf-trees"? 



12. Give illustrations of the amount of water given up by 

 plants. 



13. What does this suggest as to the value of forests? 



