158 



THE FIRST BOOK OF BOTANY. 



EXEKCISE LX. 

 Parts of the Trunk, 



FIG. 266. 



Bark. 



Pith. 



Wood 



In living trees there grows eacli year a ring of 

 wood between the old wood and the bark, and by 

 counting the rings you can tell the age of the tree. 

 Fig. 266 is a picture of the end of a tree-trunk. A 

 dark and light streak, taken together, represent a 

 yearly ring of wood. Can you tell how many years 

 it was in growing ? When you see saw-logs, find out 

 their ages by counting the rings. Observe whether 



O / O 



these annual layers are always of the same thickness. 

 Notice whether the wood of a tree, from the centre 

 to the circumference, is all of one color. 



