REVIEW OF THE BOOK 309 



Where does the plant secure its oxygen? What is meant by 

 respiration in plants? How is it compared with respiration in 

 animals? When does respiration chiefly take place? How may 

 respiration be demonstrated (194a)? How else is oxygen secured 

 than through the aerial parts? Do roots need air? Why? 



What element is most abundant in plants? Whence is it de- 

 rived? How does it become plant-food? Define photosynthesis. 

 Compare it with respiration. What is assimilation (198a)? What 

 is chlorophyl (1986)? What is plant-food (198c)? In what sense 

 may it be said that plants "purify the air?" 



How does heat affect plants? What degree of heat is necessary 

 for certain activities? In what parts of the world do green or 

 succulent plant tissues most abound? Are all plants equally 

 affected by similar temperature? 



What substance results from photosynthesis? What becomes 

 of it? Illustrate how starch may be detected (203&)? What are 

 the internal and external evidences of growth? Note that when a 

 plant ceases to grow it begins to die. In what parts do young 

 stems elongate? How does the root behave in this respect? How 

 may these differences be shown? How is increase in diameter 

 effected? Why does the external bark become furrowed and crack 

 and break away? What is meant by the word "sap" (207a)? 



How is irritability expressed? Name some visible move- 

 ments of plants. How do plants move with reference to light? 

 With reference to gravitation? What is meant by the phrase 

 "reaction of plants to their environment"? 



Chapter 9 



We now discuss the propagation of plants. 

 Note that the chapter is divided into three co- 

 ordinate parts: (1) a discussion of the general 

 means by which plants are propagated; (2) prop- 

 agation by means of seeds; (3) propagation by 

 means of buds. 



