368 Field, Forest, and Wayside Flowers 



almost completely the union between leaf and 

 branch. Then, some frosty night, a thin plate of 

 ice forms in the absciss layer, and the separation 

 between leaf and branch is finished and final. 

 When the morning sun melts the ice the leaves 

 will shower from the boughs, however calm the air. 



And now Nature doctors the wound made by 

 the leaf's fall. The broken ends of the bundles of 

 fibres and vessels left at the scar are covered (in 

 many trees) with a protecting gum, and a little 

 later they are encompassed by the growth of the 

 cork-seal, and the healing of the scar is complete. 



The falling foliage of the horse-chestnut leaves 

 scars large enough to show clearly the marks of 

 Nature's surgery. The cork-seal, which is much 

 in evidence, has a horseshoe-shaped outline, and the 

 slightly projecting ends of the fibre-vascular bundles, 

 overlaid by a dark, glistening gum, suggest the 

 horseshoe-nails (Fig 99$). 



What falls from the bough in autumn is little 

 more than the dead skeleton of the summer leaf 

 mere dry skin, empty cells, and stringy fibre. Al- 

 mos-t all the living substances which once filled the 

 leaves were withdrawn from them before they fell, 

 and are now safely stored away in trunk and boughs. 

 Professor Von Sachs, author of the " Physiology 



