174 Our Field and Forest Trees 



Knotholes in the bodies of trees are the cavities 

 left by dead and decaying limbs. 



Sometimes a bough becomes weak because the 

 sister boughs above it are taking more than their 

 share of air and light. The plant and insect 

 enemies that attack the weaklings of the forest 

 prey upon the starveling branch and it dies. It 

 rots slowly away, its twigs fall; at last a gale or 

 an ice storm snaps it off the tree, and a raw scar 

 is left on the trunk. 



The tree makes an effort to cover the scar. 

 New wood and new bark are made each spring in 

 a raised ring, which closes slowly over the scar if 

 it can. 



But if a branch is broken or cut away from the 

 tree so that a long stub is left sticking out, the 

 ring of new wood and bark cannot rise high 

 enough to cover the bare place. 



Seasons come and go, and the stub does not 

 " heal in." If the tree has been pruned, it is a 

 lasting disgrace to the man who did the pruning. 

 And the bare surface of the exposed wood, over 

 which bark cannot grow, is a trap to catch and 

 hold any stray tree enemies that fly abroad. If 

 the branch had been cut away close to the trunk, 

 new wood would have formed each spring over 

 its surface, and by and by the trunk would have 

 been smooth and symmetrical, showing no scar. 



There are of course differences among the trees 

 in their power of healing. It varies in different 



