WHY LEAVES TURN BROWN 349 



green, or even as one of its constituents. It does not 

 satisfy. Pale green from dark green does not leave 

 yellow it leaves blue. Blue-green from green may 

 leave yellow, but not the rich positive yellow of the 

 maple. No painter can add beech-red to beech- 

 green without making mud, or paint the flaming 

 Ampelopsis leaves so as to make them a transparent 

 green. Nevertheless, Nature may have done it, and 

 it is the element of miracle in them that makes the 

 autumn tints so delightful. The miracle is really in 

 the summer green, but only the denouement of autumn 

 awakens us to the fact 



The popular belief that the leaves are nipped off 

 by the cold night of autumn is as remote from the 

 facts as the poet's cry that the young buds of next 

 year push off the leaves that have had their day. In 

 other climes the leaves come off at the approach of 

 hot weather, and grow again when the cool rains 

 come. They fly from the tree like intelligent units 

 when they are about to become a burden instead of 

 a help. The snows of winter would break the tree 

 down if there were broad leaves to settle on ; the 

 scorch of the dry season would make it perspire to 

 death. So in each case the leaves desert while the 

 bad time is scarcely more than imminent. The order 

 of course comes from the roots. The flow of sap, 

 which has been abundant and regular while summer 

 lasted, begins to fail when cold rains have chilled the 

 soil, or the tropical sun has dried up the supply. 

 Leaf transpiration comes to exceed the intake, and at 

 last the tide flows the other way. The outposts are 

 not driven in, but recalled. The starches and the 

 sugars that the chlorophyl has been making pass from 



