THE STEM 37 



he thin, as in the lemon-scented gum tree or the plane 

 tree. As this bark peels off, fresh bark forms, and 

 the tree is not hurt. Indeed, the tree is often 

 healthier for losing this bark. The plane tree is able, 

 in this way, to throw off the dust that gathers on the 

 stem in summer ; and this is one reason why it is so 

 good a tree for our dusty streets. 



6. Sometimes, as in a young wattle or lemon-scented 

 gum., the outer bark is so thin that a scratch of the 

 finger-nail shews the green layer of the bark. Most 

 trees, however, have a thick, dead outer bark to 

 protect the tender growing new bark and new wood. 

 You can now see that the living part of a tree — the 

 xiew bark and new wood — lies between dead bark and 

 dead wood. You will now understand how, by 

 ringing, we can kill a tree without cutting the tree 

 jight through. All that we have to do is to cut 

 through the bark to the new wood. You will under- 

 stand also how it is that after a bush fire many of the 

 trees are able, in a short time, to throw out new shoots. 

 The living part of the tree was protected by the outer 

 dead bark, and so new shoots can be made from the 

 tree's reserve stores. Our " bush " trees, you see, 

 have to lay up stores, not for a rainy day, but for a 

 ■day of fire. Many of you have seen, within a few 

 weeks of the fire, a beautiful fringe of green running 

 along the blackened branches. 



7. A one-year old stenn. And now you are ready 

 to see for yourself how wood and bark grow. Take 

 .a one-year old shoot of any quick-growing wood like 

 the banksian rose, and make a slanting cut with a 

 .sharp knife. In the centre you have the soft pith, fig. 



