110 



STEMS 



FIG. 39. 



Sketch. After a week or two 

 carefully remove the plant 

 and notice whether the root 

 growth has been affected. 



Query. Why do corn, 

 wheat, etc . , tend to straighten 

 themselves when they have 

 been blown over by the 

 winds? How do you account 

 for lopsided trees which grow 

 at the edge of a forest ? 



Why are the young trees 

 in the forest so tall and 

 slender ? 



104. STEMS 



Object. To study the effect of sunlight on the growth 

 of stems (heliotropisrri). 



Apparatus. A dark box having one small hole for admission 

 of light, seedlings in a small flowerpot. 



Method. Place the plant in the dark box and leave it 

 there for several days. Notice the effect of darkness on 

 color and size of the stem. Observe the direction in which 

 the stem grows. 



Compare a plant grown in the dark with one of the same 

 sort grown in the light. How do they differ in length, color, 

 size of the leaves, distance between leaves, etc. ? 



Conclusion. State in three sentences what you have 

 learned by this experiment. 



Suggestion. Place a potato in a glass of water so that 

 the under side is moist ; set it on the window sill where there 



