CHAPTER XIII 
HOW PLANTS GIVE OFF WATER 
What becomes of the water taken up by the plant? 
We have learned that the food which the plants take 
from the soil is taken up along with the water in which 
it is dissolved. We know that the solutions of plant 
food must be weak, or the plant is not able to absorb 
them. A large amount of water, then, is taken up by 
the plant in order to obtain even a small amount of 
food. We know also that water is taken up by the 
roots of the plant independent of the food solutions 
in it. It is of great interest, then, to know what 
becomes of the large amount of water absorbed by the 
plant. Some of the water is used as food by the 
plant, but 1t would be impossible for a plant to use 
for food all the water which it takes from the soil. 
Loss of water by living leaves. Take a handful of 
leaves, or several leafy shoots from fresh plants. Place 
them on the table and cover them with a glass jar, as 
in Fig. 130. Place another jar by its side, but put no 
leaves under it. Be sure that the leaves have no free 
water on them and that the jars are dry. In the 
course of fifteen or twenty minutes you can see a thin 
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