THE NUTRITIVE ORGANS OF PLANTS 



59 



it to stand in sunlight or a warm place until the red color 

 appears in the leaves. 



1. Give an account of the experiment, stating your observa- 



tions. 



2. What do you conclude as to the part of the leaf through 



which soil -water is distributed to different parts of the 

 blade? 



3. What cells of the root did you find specially adapted for 



absorbing water from the soil ? Through what regions 

 of the root and stem is sap carried up to the leaves ? 



69. Is water vapor given off by the leaves of a green plant? 

 Laboratory Study No. 37. Demonstration. 



1. Wrap sheet rubber or thin oilcloth about a pot containing 

 a vigorous plant which has been thoroughly watered. 

 Tie the rubber or oilcloth tightly about the stem to 

 prevent the escape of 

 water from the soil. If 

 rubber tissue cannot be 

 obtained, melted paraffin 

 may be poured over the 

 soil, and the pot painted 

 with hot paraffin. Cover 

 the plant thus prepared 

 with a large bell jar with 

 the inner surface dry, and 

 stand it in the sun for a 

 few hours. 



a. Describe the preparation of 

 the experiment, stating 

 the reason for using the 

 rubber or paraffin. 

 6. State your observations and 

 conclusion. 



c. Why is the bell jar necessary? 



d. What becomes of the water 



vapor given off by the FIG. 23. -Apparatus to show the 

 leaves of trees? excretion of water from a plant. 



