122 NOT ALTOGETHER ABOUT PLANTS 



Section 38. 1. What is evaporation? 2. What is transpiration? 

 3. More plants die as a result of evaporation than from all other 

 causes. Why is this so ? 4. Evaporation is the greatest danger to 

 plant life. Is it a necessary danger? Explain your answer. 5. Ex- 

 plain why hot weather is much more uncomfortable in a moist climate 

 than in a dry one. 6. In Arizona water is kept cool by placing it in 

 porous vessels and hanging them up out of doors. Can you explain 

 this ? Why is it better to hang the vessel up in the air ? 7. Devise 

 an experiment for proving that a plant gives off water by evapora- 

 tion. 8. Devise an experiment for showing just how much water a 

 plant gives off by evaporation. 9. Devise an experiment for showing 

 the difference in rate of evaporation between a leaf surface and an 

 equal area of water surface. 10. What are some of the ways in 

 which you would expect the structure of plants which live in deserts 

 to be different from the structure of plants which live in moist and 

 shady forests ? 



Section 39. 1. Define physics and chemistry, and give examples 

 of the kind of facts which each considers. 2. Why is it necessary 

 to understand something of physics and chemistry in order to under- 

 stand the life of plants? 3. In what respect is life like a whirlpool? 



