126 Our Field and Forest Trees 



time the trunks and boughs, living out in the cold, 

 give no sign of awakening. 



In the time of leaves, the water which comes 

 into the tree by way of the root-hairs finds its way 

 at last into the leaves. There some of it is sep- 

 arated into the substances and gases which have 

 been blended to make it — separated, sorted, made 

 over new into tree food — some of it is perspired 

 away through countless tiny pores in the leaves. 



But in earliest spring, when the root-hairs begin 

 their work the buds on the branches above are 

 still sleeping. There are no leaf-laboratories 

 where the earth-water can be used in making food 

 for the tree, and no leaf-pores through which it 

 can pass out into the air. 



Soon all the outer part of the trunk gets filled 

 with water; the youngest cells of the wood are 

 swollen with it. As the earth-water creeps 

 upward, it finds its way into many cells in which 

 starches and other plant foods are stored. These 

 provisions were gathered by the tree last summer, 

 and were laid away in some cells of the wood to 

 feed the buds of spring in their first growth. 



When sunlight bathes the boughs and life stirs 

 at the roots, these stored-up starch grains become 

 changed into glucose, which is a sort of sugar. 

 This mixes with the earth-water coming up from 

 the roots, and the result is a sweet fluid creeping 

 on towards the branch tips. As old farmers say 

 " the sap is stirring." 



