82 TREES IN WINTER. 



ually_interrupted the growth of the branch, and 

 that another bud has grown from a leaf-axil to 

 supply its place ; while in the straight branches of 

 the Beech the terminal bud has carried on each 

 bough year after year. He knows that the rough- 

 ness of the apple and cherry twigs (Fig. 16) are 

 due to the multiplication of bud and leaf scars, 

 caused by the very small yearly growth ; and that 

 the Lilac-bush is continually forked because the 

 axillary buds have grown and the terminal bud 

 has been suppressed (Fig. 14). And this under- 

 standing of the ways of growth should open his 

 eyes the more to the variety and beauty they 

 create. 



When the winter is safely passed, the first per- 

 ceptible change that takes place in the tree is the 

 conversion of the dry, starchy food materials stored 

 in the branches into a sugary sap. 1 This chemical 

 change is largely brought about by the absorption 

 of water. The liquid thus produced occupies a 

 greater space than did the dry starch, and causes 



1 "The stimulus to the movements of material, however, is always 

 given by the growth of the young organs. The buds of a tree put 

 forth shoots in the spring by no means because the nutritive sap enters 

 into them, as people are in the habit of saying, but exactly the reverse : 

 the nutritive matters are set in motion because the buds begin to 

 grow." Sachs, " Lectures on the Physiology of Plants," p. 364. 



