loa 



Introduction to Botany. 



nodes of the shaded and unshaded shoots, and also the 

 sizes of the leaves formed after the experiment was started. 

 What is the effect of absence of light on the growth of 

 stems and leaves ? 



99. Plant some seeds of Indian corn and garden bean 

 in moist sawdust contained in a wire basket, which should 

 be inchned as shown in Fig. 44. Keep the sawdust moist, 

 and note the direction taken by the roots after they have 



grown down through the meshes 

 of the wire at the bottom. What 

 does this experiment teach as to 

 the probable behavior of roots 

 under natural conditions ? 



100. Bend over a vertical shoot 

 of some thrifty plant, and fasten 

 it down in such a way as to allow 

 freedom of action toward the apex. 

 Observe the position finally taken 

 by the stem and leaves. How do 

 you account for the change of 

 position observed, and what is its 

 use.' 



loi. Shade a plant so that it receives light on one side 

 only. How do the leaves and stems behave, and to what 

 purpose .'' Remove the screen after a marked change has 

 been noticed, and note whether the different members 

 assume their former positions. 



102. Invert a plant and notice the direction taken by' its 

 growing members. Do those parts which have ceased to 

 grow change their positions ? After a day or so set the 

 plant upright and note whether the parts come back to 

 their original positions. 



103. Observe the behavior of the tendrils of plants 



Fig. 44. 



Experiment to show hydrotropism 

 of roots. After Sachs. 



