CHAPTER III 

 NOT ALTOGETHER ABOUT PLANTS 



28. A Break in the Story. — We cannot very well go 

 straight ahead with the story of plant life. Like other 

 stories, it must be interrupted for explanations. Certain 

 matters, though not exactly a part of the story itself, must 

 be explained so that the story itself may be understood. 



Already some things have been mentioned which you 

 may not understand. Evaporation and solution have been 

 mentioned. Do you understand them? Carbon dioxide 

 and oxygen have been mentioned. Do you know what 

 they are? Light and heat were called forms of energy. 

 Do you know what energy is? You were told that sub- 

 stances enter the plant. Have you any idea how they 

 enter it? All these and some other matters need to be 

 cleared up before we go on. They all have a great deal 

 to do with plant life. 



20. Solution. — Let us begin with solution. With it 

 you have had experience. You have stirred sugar in tea 

 or coffee or lemonade. You know that gradually the sugar 

 disappears and gradually the tea or whatever it is becomes 

 more or less sweet all through. How sweet it is depends 

 on how much sugar you have put in, but no matter how 

 much you put in it is as sweet in one place as it is in an- 

 other. The sugar has become equally dissolved all through 

 it. Solution has occurred. 



Solution is the name of a process by which one sub- 



