CHAPTER XXXIII 



Draining 



At the bottom of a flower-pot there is a hole. 

 A fragment of earthenware is placed over this 

 hole, and if the plant is delicate this is covered 

 with a layer of small stones. When these 

 preparations are completed the pot is rilled 

 with earth. What is the use of the hole, the 

 fragment, and the layer of stones ? Let us 

 find the answer to this question. 



Water is absolutely necessary to plants, for 

 it is by this means that the different nutritive 

 substances contained in the earth are dis- 

 solved, so that they may be absorbed by the 

 roots. For this purpose the earth entered by 

 these roots must always contain suitable 

 moisture, provided either by rain or by water- 

 ing. But air is no less indispensable. It 

 purifies the ground and by slow combustion of 

 the soil gives out a small but constant supply 

 of carbonic acid gas, which is the food of 

 vegetable life. Deprived of its life-giving 



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