WHY LEAVES TURN BROWN 351 



not so. The leaves withered in a day, but they never 

 turned yellow, and are even now hanging on the 

 wounded branch. They will survive even the orderly 

 retreat of their yellow fellows now mustering for the 

 last review. The cork-forming habit, then, so far as 

 it relates to the base of the leaf, is purely autumnal. 

 It is something so much higher than the automatic 

 back-flow that follows decreased pressure, that it is 

 almost worthy the name of intelligence. It is, at 

 least, a seasonal habit that stands very much for the 

 preservation of the tree. 



It is a rule that the trees that first went into leaf in 

 spring retain their autumnal glory longest. At the 

 end of May the freshest green was that of the ash, 

 following much other foliage that had already passed 

 into the sober hue of middle age. And now the ash 

 is stripping off its pennons so rapidly that they have 

 no time to get rid of their chlorophyl first. The elder, 

 which gave its treasured wisps of green in February, 

 still shelters the thrushes in a complete dome of leaves 

 as they sit and gobble the rich black berries. " The 

 brushwood sheaf round the elm-tree bole," which 

 burgeoned more than a week before the upper 

 branches, has not yet caught the yellow fire which 

 has consumed the topmost sprays, and is burning the 

 great middle portion. On the other hand, long after 

 the lower boughs of the poplar have yellowed and 

 become bare, the top will bear plumes almost as green 

 as the mistletoe that the storm-cock has planted 

 among them. Differences of character, not merely 

 between species, but between individuals, constantly 

 present themselves as we pass through the field of 

 battle. A single sycamore within twenty yards of 



