70 OUR WOODLAND TREES. 
representing the first year’s growth; the suc- 
ceeding rings of wood outwards representing the 
growths of succeeding years. By these interesting 
marks the age of a Tree can be ascertained—only, 
however, after it has been cut down, or some 
part of its trunk has been cut across. 
If we take a completed first stage of the growth 
of a Tree—we may select for the purpose, as being 
one of the most familiar, both to town and 
country people, the Lime, and a stem of the age 
of one completed year will suffice for illustration— 
we shall find that the stem is built up of tissue 
in the following manner. There is a central 
column of cellular tissue, forming what is called the 
pith. Over this is a layer of wood tissue, mixed 
with a portion of vascular tissue. Nextis a layer 
of bast tissue, or incipient inner bark. Then a 
layer of cellular tissue, or incipient outer bark. 
But running through the inner cylinders of 
tissue from the inner column or pith to the 
outer cylinder or bark are thin rays of cellular 
tissue. The direction taken by these rays or 
lines of cellular tissue may be indicated by com- 
paring them to the spokes of a wheel. The 
