58 FIEST STUDIES IN PLANT LIFE 



(7) Fig. 33 shows a rose-shoot growing in the deep shade of a 

 fence. Fig. 34 shews shoot of the same rose that has overtopped 

 the fence. Explain why the one "runs to "stem and the otlier 

 to leaf. 



(8) " Laying " of wheat is due to the plants being so crowded 

 that the stems get too little light. This makes the stems weak. 

 Try to see cases of this kind. 



Composition Exercise. — But for the plants, the air would 

 soon be poisonous to us. Explain this. 



Drawing Exercise. — Draw (a) a seedling grown in the light ; 

 (b) a seedling of same kind, grown in the dark. 



Or Draw (a) sunflower by day ; (b) sunflower after sunset, or 

 after being put in a dark place. 



X.— THE LEAVES.— Part II. 



1. A plant is mostly built up from air and water. 



"We have seen that the work of getting food out of the 

 air is done by the Uving green stuff in the leaf with 

 the help of the sun. The leaf must also have the 

 help of water : you know how a leaf wilts if it does 

 not get enough water. This water conies from the 

 root which sends up also the Ume and nitrogen and 

 other foods that the leaves cannot get out of the air. 



2. But the greater part of the plant-food is got fi'om 

 the air by the leaves. You can see this for youi-seK 

 every time you burn a dried plant. The bush disappears 

 into the air, leaving only a little ash. The bush was 

 built up mostly out of the air, and therefore most of it 

 passes again into the air. The nitrogen and any water 

 still left in the bush escape also into the air ; and the 

 little heap of ash that remains shews us how small is 

 the amount of other food that the plant got from the 



