PLANTS GIVE OFF MOISTURE 



91 



small glass (Fig. 32) , adding water enough to rise a third of the 

 height of the egg. Then set the apparatus aside, and examine 

 it from time to time. Observe it after an hour 

 or two, if possible. 



d. What do you observe in the glass tube? 

 How does this show that water passes through 

 the skin at the larger end of the egg? If 

 water were free to enter through ordinary 

 holes in the skin of the egg, would anything 

 rise into the glass tube? 



e. A small potted plant, such as a geranium, 

 or some plant out of doors, may be cut off 

 about 5 cm. above the ground, and a glass tube 

 may be fastened to it by means of a rubber 

 tube or by adhesive tape (Fig. 33, this manual). 

 The glass tube should be filled with water to 

 the top of the tape or rubber. If the plant is 

 kept watered, sap will rise into the glass tube. 



If possible, try the experiment, and 

 note how high the liquid will go. 



EXERCISE 87 

 PLANTS GIVE OFF MOISTURE 



Apparatus and Materials. Plant, card- 

 board, knife or shears, paraffin (white 

 wax), cloth or brush, large tumbler or 

 fruit jar. 



a. Select a thrifty plant, such as 

 a geranium, growing in a pot, and 

 water it thoroughly (Fig. 34). Cut 



out a piece of cardboard larger than the top of the pot; 



in it make a round hole that will just fit the stem of the 



Fio. 33 



FIG. 34 



