GREEN PLANTS SOLVE LIFE PROBLEMS 257 



units of (9) material called (10) These have (11) . 



sizes and shapes, according to the (12)_: of structures they form. 



But they are always very tiny and grow by (13) into more 



(14) like themselves. Living things use (15) for this 



purpose. Then things that are alive (16) to (17) from 



outside themselves. They are thus said to be (18) They are 



also dependent upon the (19) of their (20) and if any of 



these are changed, it may mean the death of the living things there. 



STORY TEST 



MARY WRITES ON BEING ALIVE 

 Read carefully and critically. List all the errors and suggest corrections. 



I know that I am alive. How do I differ from something that 

 has no life? Well, that isn't hard to say. I can jump about and 

 play and move and a dead thing can do none of these things. 

 However, I haven't told what being alive is. 



People used to think that living things came from dead things, 

 like flies from dead horses or snakes from horsehairs. Some 

 people still believe such things. But Louis Pasteur, the French 

 scientist, proved they were wrong hundreds of years ago. 



A living thing always thinks. A living thing has a special 

 shape, both legs and arms. It hears, it moves, and it has weight. 

 Oh, yes, and a living thing grows and uses food for this purpose. 

 But I do not know what life is any more than do the scientists. 



PROBLEM II. HOW DO GREEN PLANTS SOLVE 

 THEIR LIFE PROBLEMS? 



Green Plants Make the Food of the World. There 

 have been sun worshipers among men since earliest 

 times. But there has never been a more ardent sun 

 worshiper than a green plant. And there has never been 

 an engine that has done more or better work than the 

 mills that are found within the green leaves of plants. 

 These mills get their power from the sun and can run 

 only in the sunlight. It is a wonderful story that of 

 how the green plant does its work. And it is all the more 

 wonderful because without this work you and I could not 



H. & W. SCI. I 18 



