86 NATURE TEACHING. 



how they enwrap the delicate, young, growing 

 points the buds. 



5. Examine a plant of onion whilst it still 

 has green leaves. Note how it is wrapped 

 round by a number of dry scales. Look at 

 the fresh leaves, notice what their lower por- 

 tions are like, and see that in reality the whole 

 onion bulb is composed of the thickened bases 

 of leaves, some of which are already above 

 ground and green, whilst the younger ones are 

 contained in the central bud. These points can 

 be readily made out by cutting onions both 

 across and lengthwise. 



6. Examine plants of Gloriosa and the 

 ' cat's-claw ' and note how the leaves form in the 

 one case tendrils, in the other case hooks. Com- 

 pare the behaviour of these leaf- tendrils with 

 the stem-tendrils already seen. 



STRUCTURE OF LEAVES. 



1. Observe the veins of the leaves under 

 examination. See how much firmer they are 

 than the rest of the leaf, how they support the 

 softer tissue. Hunt among decaying leaves 

 under trees and try to find some ' skeleton ' 

 leaves in which, the soft parts having gone, 

 the hard and more resistant veins remain as a 

 skeleton of the leaf. 



