Exchange and Movements of Gases and Liquids. 59 



Fig. 36. — A bent tube is attached to tlie stump of a plant by means of a section 

 of rubber tubing, and conducts the sap exuded into a test tube. The excised shoot 

 is placed with its base immersed in a cylinder of water, to ascertain amount of 

 water taken up. After Oels. 



most convenient to allow the liquid to compress a column of 

 air, and its volume will indicate the amount of pressure exerted 



