Part IV.] 
PRUNING AND THINNING. 
227 
ward growth of the head of the tree, joins or 
anastomoses with it, and passes round the side 
of the branch down the stem. Thus, above, 
and below, and on the sides of the branch, each 
annual growth of the branch and of the stem is 
not two growths, but one growth, and it cannot 
be said where the growth of the branch ends 
and that of the stem begins ; and the part of the 
branch within the stem is much more like the 
roots of a tree than a cone. When the tree is 
cut up in the saw-pit, if the saw does not strike 
the pith of the branch exactly lengthwise, if it 
cuts the branch diagonally lengthwise, the branch 
will form a double cone and taper both ways at 
once. If this double cone chance to be divided 
across the centre, the two parts of the same 
branch will on one board show as a cone taper¬ 
ing outwardly, and in another as a cone tapering 
inwardly. The double cone I allude to, will be 
easily seen by cutting a small branch across 
with a long slant . De Candolle’s internal cone 
would only exist if the annual downward growth 
in girthing of the branch ceased when it arrived 
at the stem; but as this growth does not cease 
here, a branch unduly large in proportion to the 
head of the tree will form from its own deposit 
an excrescence below it where it joins the stem; 
q 2 
