THE STALK OF THE PLANT 73 



tion would cause the death of the tree, since through 

 it the nutritive juices of the earth reach the buds, 

 leaves, and young branches. In their time the in- 

 terior layers, one by one, when they formed the sur- 

 face, rendered the same service to the buds of their 

 day ; but now that these buds have become branches 

 the inner layers have only a secondary office, or even 

 none at all. Those nearest the outside still have 

 some aptness for work and help the layer of the 

 year to carry the juices from the earth to the 

 branches. As to the innermost ones, they have lost 

 all activity ; their wood is hard, dried up, encrusted 

 with inert matter. In their decrepitude these in- 

 terior layers are incapable of service in the work 

 of vegetation; the most they can do is by the sup- 

 port of their firm woody structure to give solidity 

 to the whole. Thus the tree's activity decreases 

 from the outside toward the center. On the surface 

 are youth, vigor, labor; in the center old age, ruin, 

 repose." 



