4 Characteristics, Structure, Life of Trees 
he base of the daughter branch more and more, while the 
atter itself is also growing in diameter. 
Fic 6 — Method of formation 
of a knot. Seven annual 
layers of wood, a, b, basal 
parts of a limb which hved 
four years, then died and 
broke off near the stem 
This leaves a “sound” knot 
to the left of a, the branch 
stub to the nght forming a 
“dead”? knot soon to be cov- 
ered by the growing stem 
(From Department of Agri- 
culture, Forestry Bulletin, 
No 10). 
The forester is interested in this 
method of branch formation, be- 
cause he knows that, owing to it, 
every branch or limb which once 
existed will produce a “knot” in 
the lumber, although this lumber 
may be sawed from an apparently 
branchless bole. As long as the 
limb remained alive, this will be 
a “sound” knot; after the limb 
has died, it will be a “loose” 
knot (in conifers), or a decayed 
knot, leaving a blemish or hole in 
the board. The forester, there- 
fore, attempts to grow his trees so 
as to kill out most limbs as early 
as possible in order to reduce the 
size and number of knots and thus 
secure a branchless bole. 
When, however, a branch is 
broken or cut off, a dormant bud 
may develop into a branch. Such 
dormant buds are connected with 
the pith by a fine trace of pithy 
material not large enough to be 
noted as an imperfection. 
There is an interest in this 
structural peculiarity which con- 
cerns the tree-warden. The center 
or pith of the branch or bole, which forms a direct and 
continuous communication through the entire tree from the 
