THE FALL OF THE LEAF 271 



as food-formers, and it becomes important for the tree 

 to get rid of them quickly and without violence. If 

 the leaves were merely to die in their place, nothing 

 short of a gale of wind would strip the tree,. and 

 probably no ordinary gale would suffice, as a fact 

 shortly to be mentioned concerning the Oak and 

 Beech seems to prove. A whole gale, sweeping over 

 a leafy tree, would be attended with loss of twigs as 

 well as of leaves. We see what damage is done by a 

 high wind in summer, when the tree is clothed with 

 firmly adhering leaves. It is much better that the 

 leaf should fall of its own accord in still weather, 

 and return its substance to the soil about the 

 roots, instead of being whirled to a distance. Most 

 of our trees are able to shed their leaves without 

 waiting for them to be torn off, but there are a few 

 unexplained exceptions. The Oak and the Beech 

 keep their leaves long, especially when young. The 

 Turkey Oak keeps its leaves even when it has grown 

 into a large tree. Are these trees adapted to more 

 sheltered situations than others, or are their branches 

 better able to withstand a strain ? It is well to put 

 these questions, but I must confess that I cannot 

 answer them. 



Leaves about to fall commonly change colour. The 

 chlorophyll either disappears, or is converted into new 

 colouring-matters. The supply of water and sap is 

 arrested, and both leaf and leaf-stalk shrivel. At the 

 base of the leaf-stalk is an enlargement or cushion, 

 and in compound leaves there is often such a cushion 

 to every leaflet. Though the rest of the leaf and leaf- 

 stalk shrink, the cushion remains plump. Let us stop 



