110 WATER 



experiment will prove that capillarity acts in plants, as 

 well as showing where the sap rises. 



Experiment 55. Capillarity in Plants. 



Apparatus : Glass, knife. 



Materials: Red ink, twigs of any tree having flat 

 leaves. 



a. Cut a few twigs and put them immediately into 

 some water which is strongly colored with red ink. Place 

 the glass in the sun and in a draft of air, if possible. At 

 the end of ten minutes remove one twig and split it 

 lengthwise. Where did the colored water go? Remove 

 another twig at the end of half an hour and examine in 

 the same way. Leave another twig for a full day. How 

 do the leaves appear? How did the colored water get 

 through the stem? Make a drawing of the twig, split 

 lengthwise, showing just where the colored water passed 

 through it. 



If the stalks of plants are not woody, they receive 

 their stiffness from the capillary tubes in them being full 

 of water. If the plants do not receive enough water the 

 tubes become empty and the stalks flabby. We say that 

 the plants wilt. When is a garden hose stiffer, full of 

 water or empty? 



Review Questions, 21. 



1. What was the position of the Great Dipper last 

 night at eight o'clock? 



2. What are the uses of nitrogen? 



