The soil and the plant 



71 



breathing in every part, in the roots as well as in the 

 leaves. 



Now turn to what you have seen in your walks. 

 You would probably notice that on the drier, sandy or 

 gravel ground there was nothing like as great a growth 

 of grass or of other plants as on the moister soil. This 

 is so much like what we found in the pot experiments 



Fig. 33. 

 This wheat growing on very this wheat growing on rather 

 moist soil was still green dry soil was yellow and 



and growing vigorously, ripe 



whilst 



that we shall not be wrong in supposing that the 

 difterence in water supply largely accounted for the 

 difference in growth. But you may also have noticed 

 something else. Plants in the drier soil have generally 



