SECTION OF THE TREE. 101 
mosses or lichens, which give it the look of old 
age, it will stand in the orchard or take its 
place in the forest in much the same sort of 
character as a gentleman of five-and-fifty stands 
in human society. 
If we were now to take a saw and cut across 
the stem of the tree, we should find a very curi- 
ous change to have 
taken place in the 
wood, A number of 
distinct circles, like 
those represented 
in the cut, are seen 
to surround the 
pith which is in 
the centre. And 
also a number of 
lines are observed 
running from the 
centre to the outermost ring. These circles 
are the rings of wood mentioned at page 41, and 
called concentric rings, or zones. The lines which 
give the piece of wood a star-like look are called 
medullary rays, and are supposed to be intended 
to connect the pith with the circumference of the 
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SECTION OF AN EXOGEN. 
