Part IV.] 
PRUNING AND THINNING. 
239 
over there, and from D D to E E would have 
been solid clean timber instead of a disunited 
knot. So that there would have been no dis¬ 
united knot at all, but only a cross-grain, formed 
by the living branch firmly united to the stem, 
and decreasing in size towards the centre of the 
tree, with a scar at the end D D, like that at 
E E. This scar would form no greater flaw in 
the timber, than one arising from a small piece 
of bark being knocked off the stem. If the 
branch had not died, the cross-grain would not 
only have been annually prolonged as long as 
the tree continued to grow, but would also have 
increased in bulk every j^ear: for De Candolle’s 
cone, whose apex is at the pith, and whose base 
at the bark of the stem, describes most accurately 
the form of the cross-grain occasioned by a 
living branch in the timber of a tree. If the 
branch when it died had not been cut off at 
E E, the existing disunited knot would have 
been prolonged; that is, from E E in the di¬ 
rection of F, as long as the tree grew, and the 
branch remained on it, a disunited knot would 
have been inclosed in exchange for the deposit 
of solid, clean, straight-grained timber. For 
that the grain becomes straight as soon as the 
scar is healed over, may be seen in Plate II. 
