174 



156. SLEEP OF PLANTS 



Object. To show the effect of light on the position 

 and motion of plants. 



Apparatus. Oxalis or clover plants in flowerpots. There 

 should be two of each sort. Young, healthy plants are preferable. 



Method. Place 

 one plant in the 

 strong sunshine for 

 half an hour and 

 the other in a dark 

 closet. 



Remove both 

 plants to a shady 

 place and compare 

 their appearance. 

 Now reverse the 

 process, putting the 

 plant which was in 

 the light into the 

 closet and the other 

 in sunlight. After 



half an hour again compare. Result? Why? 



Conclusion. State your judgment of the cause of these 



movements. 



157. SLEEP OF PLANTS 



Object. To study the so-called sleep movement of plants. 



Apparatus. Oxalis or any of the common leguminous plants, 

 such as clover, sweet clover, desmodium, or locust. 



Method. If the plant is potted, place it in strong sun- 

 light for half an hour. Observe the attitude of the plant. 



FIG. 73. Sleeping oxalis. 

 (Photographed by A. H. Lewis.) 



