EXERCISE 75 

 CAN THE ROOTS AND STUMP OF A PLANT FORCE WATER UPWARD ? 



Materials. A plant with a stem about -| inch in diameter (a potted plant or one growing out of 

 doors will serve for the exercise) ; glass tube with small opening ; rubber tubing of size to fit closely 

 over the stem and glass tubing ; small cord or copper wire. 



Directions. Arrange apparatus as follows: Cut off the top of the plant about 2 inches above 

 the ground. To the stump of the stem which is connected with the roots attach a glass tube by 

 means of a short piece of rubber tubing, and support the glass tube in a vertical position. It may be 

 best to insure a tight joint by wrapping the tube tightly with cord or wire. A glass tube with a 

 small bore will give more striking results. Water the soil freely and observe the apparatus at inter- 

 vals of a few hours to see if water is being forced out of the cut end of the stem. If water is forced 

 upward, determine the amount and the rate of rise. 



Additional problem. If a grapevine is cut in the springtime it " bleeds." Why ? When maple trees 

 are tapped, what is the source of the water which comes from the wound ? 



[100] 



