LEAVES 169 



152. LEAVES 



Object. To show that leaves give off carbon dioxide. 



Apparatus. Two wide-mouth jars, two vials of limewater, and 

 leaves. 



Method. Put about one inch depth of water in each 

 jar. Into one jar put a number of vigorous leaves so that the 

 leafstalks are in water and their blades in the air of the jar. 

 Leave the other jar as a control. Place a vial of limewater 

 in each jar so that it does not mix with the water of the jar. 

 Cover both jars and set them away in a dark closet for a 

 day or two. Examine the limewater in each jar. Which 

 gives the better test for carbon dioxide ? Explain. 



Conclusion. What does this show concerning respira- 

 tion of plants? 



Note. There is a trace of carbon dioxide in the air. Hence 

 there will usually be a thin scale of carbonate on the surface of the 

 limewater in each vial. 



153. LEAVES 



Object. To show that young buds respire and give 

 off heat. 



Apparatus. Same as in the preceding Experiment, a thermom- 

 eter, and several expanding leaf buds of horse-chestnut, hickory, 

 ailanthus, or maple. 



Method. Same as preceding. Test the temperature with 

 a thermometer from time to time and compare it with the 

 temperature of the air outside. 



Make similar observations with the apparatus in the light. 

 Are the results alike in both cases ? 



Conclusion. What may be inferred from this experiment ? 



