108 The Leaf 



the leaf comes out of the bud. In this last case they 

 often take the form of scales which shelter the young 

 leaves before they are fully grown. If you look at the 

 leaf bud of a cherry or horse-chestnut you will there 

 see the stipules going through every stage from scales 

 to small green leaflets. 



I said that the stalk is flexible. What do you think 

 would happen if it were not? The first storm of rain 

 or wind would strike against the flat surface of the leaf 

 and either tear it to pieces or snap the stalk in two. It 

 is usually long as well, so as to bring the leaf out from 

 the shade of the other leaves and expose it more fully 

 to the light. 



PRACTICAL WORK. 



1. You are given two laurel or ivy leaves and two softer leaves 

 (e.g. lilac) all plucked straight from the twigs. Peel a piece of outer 

 skin off one of each pair of leaves. Place all four leaves in the sun. 

 Later in the morning go and look at them and write down the 

 answers to these two questions : In what order do the leaves begin 

 to fade ? What is the reason of this ? 



2. (Demonstration by Teacher.) Two similar twigs covered 

 with leaves (a kind with good sized leaves is best) are placed in 

 specimen glasses full of water and the opening is plugged with cotton 

 wool. The leaves are then all stripped from one twig. The glasses, 

 with the twigs in, are placed on rough balances (the small ones used 

 for weighing letters will do), and are counterpoised with weights and 

 shot or pebbles. Both balances are now placed in the sun, still 

 bearing the glasses and shot. They are examined at the end of 35 hr. 

 and again at the end of 1 hr. Illustrate this experiment by diagrams. 

 Underneath your pictures answer these questions : (a) Did you see 

 any change at the end of | hr. or 1 hr. ? (6) How do you account 

 for this ? (c) What does the experiment show you ? 



3. Fold your paper in four columns, and head them with the 

 words Name, Blade, Stem, Stipules. Examine the leaves of ivy, 



