20 



LIGHT 



or less soot. How does the color of the sun appear to 

 change? 



11. The Sunlight Makes Plants Green. 



If a board or plank is laid on the grass for several 

 days, so that the sunlight cannot reach it, the grass will 

 be light yellow, and even white, when the board is first 

 removed. In a few days, however, the grass will regain 

 its usual green color. What caused the change? Pota- 

 toes and onions which sprout in the dark have very light 

 green or light yellow stalks and leaves. If these are 

 brought into the sunlight they become green. Although 

 plants may grow in the dim light they need the sunlight 

 in order to grow well and to bear fruit. 



Experiment 12. The Effect of Sunlight upon Grow- 

 ing Plants. 



a. Cut a thin slice of cork from a stopper and trim 



it into some shape, such 

 as a heart, or a cross, or 

 a clover leaf, and pin it 

 upon a growing leaf 

 which must be left upon 

 the tree. The best way 

 to fasten the piece upon 

 the leaf is to push two 

 pins through it, through 

 the leaf, and into another 

 piece of cork, which is 

 held on the under side of 

 the leaf. Do not touch it 

 for one week. At the end 



