Part IV.] PRUNING AND THINNING. 
the correspondence of the pith and grain or 
growths of the ends with those of the side may¬ 
be easily traced; and the numbering is in¬ 
tended to make this correspondence more clear. 
In the fir tribe generally, the latest annual 
shoot is surmounted by a circle of buds, or what 
is called a whorl of buds, around the leading 
bud. These whorls of buds become whorls of 
branches ; and where the piths of these branches 
join the pith of the stem, they mark in the 
centre of the tree, indelibly and for ever, the 
highest point of each successive annual growth, 
from the first shoot of the seedling, to the last 
shoot of the forest pine. C, the point where the 
pith of the branch joins the pith of the stem, 
marks also the highest point of the first annual 
growth of this board. The reason that this first 
growth is so small is, that it formed the taper 
top of the then leader of the tree. So the 
difference in the size of the main pith above and 
below the branch is caused by the junction of 
the tapering end of the pith of the older lower 
shoot, with the broad-based beginning of the 
pith of the younger upper shoot. 
On the left side of the pith of the stem, where 
there is no branch, it may be seen that the first 
annual growth of the older shoot of the stem 
