A YEAE IN SCIENCE 



81 



Directions: Place some green water plants under a 

 funnel in clear water, as in Figure 28. Place the jar 

 in sunlight for several days, and 

 allow any escaping gas to collect in 

 a test tube placed over the stem end 

 of the funnel. When there is an 

 inch or more of gas in the test tube, 

 remove the tube from over the fun- 

 nel, being careful not to take it out 

 of the water in the jar. After closing 

 the mouth of the tube with the 

 thumb, remove it from the jar of 

 water. Invert the tube, then remove Fis "- 28< 



the thumb and quickly thrust a glowing pine splinter 

 into the gas in the tube. What is the result? What 

 gas does this indicate is present? 



Repeat the same experiment, using mushrooms in 

 place of the green plants. What result do you obtain 

 this time? How do you account for the difference 

 between this result and the one obtained with the 

 green plants? 



Exercise 52. Transpiration. 



Object: To show that the excess water in plants 

 is given off by the leaves. 



Glass tumblers 

 Card board 



Apparatus 



Paraffin 

 Geranium 



Directions: Cut off a small branch of geranium. 

 Place the cut end of it through a hole in a piece of 



