226 
PRUNING AND THINNING. 
[Part IY. 
the form of a cone ; because, as the continuation 
in the stem of its annual growths is not pecu¬ 
liar to the branch, but common to the whole 
tree, they do not dry in and change colour like 
the dead branch, but remain moist conduits for 
the upward sap to the head of the tree. But as 
long as the branch is alive, the medullary rays 
and longitudinal woody fibres of the new annual 
growth of it are prolonged, and run vertically 
down that part of the stem of the tree which is 
below the branch ; so that it is only the grain 
of the centre part of the branch, that is, its first 
year’s growth, which runs across the grain to the 
centre of the tree. It then in general joins the 
second year’s growth of that part of the stem 
which is below it, and runs down the stem of 
the tree to the roots. The grain of every other 
year’s growth of the branch annually turns down 
the stem of the tree, short of the centre of the 
tree, directly as the newness of its growth. The 
same or rather the reverse appearance may be 
observed above the branch, if a living branch 
and the stem are cut longitudinally where they 
join; that is, the grain of each year’s growth of 
the branch appears to turn up the stem of the 
tree: for each annual downward growth of the 
branch meets the corresponding annual down- 
