86 The Trunk 



which in this tree grows enormously thick. The many 

 everyday uses to which it is put depend partly on its 

 lightness and partly on the fact, so important to the tree, 

 that water will not pass through it. All inner bark is 

 corklike in nature although it is only in this particular 

 tree that it is found in sufficient quantity to be of 

 practical use to us. It is full of little air holes which 

 supply the tree with air in the winter when the leaves 

 by which it usually breathes are gone. The openings to 

 the outside air are called lenticels and are quite easy 

 to see on most twigs. 



Cork is the covering with which a tree always 

 protects itself after any injury. If one of its branches 

 is cut off close to the main stem the inner bark soon 

 begins to spread itself from the sides over the wound, 

 and if this wound is not very large the cork may succeed 

 in covering it altogether and the tree will be none the 

 worse. Otherwise rain will get in and may very likely 

 begin to rot away the wood. Then in time the tree will 

 become hollow until at last only the bark and a thin 

 ring of sap wood is left. You see what serious harm 

 it may do a tree if its bark is injured. Unfortunately 

 some animals, especially deer and rabbits, are fond of 

 gnawing the bark of young trees, especially when the 

 ground is covered with snow. This is one of the dangers 

 from which newly planted trees in plantations have to 

 be carefully guarded, or the bark will be injured and 

 the tree will probably die. 



PRACTICAL WORK. 



1. Sketch two views of your log, one showing a transverse 

 section of the wood and one a longitudinal one. 



