ction of the pith or "trace" of the dormant bud in the center.

[Illustration: Fig. 17. Wavy Grain in Beech (_after
Nordlinger_).]

In the wood of many broad-leaved trees the wood fibres are much longer
when full grown than when they are first formed in the cambium or
growing zone. This causes the tips of each fibre to crowd in between
the fibres above and below, and leads to an irregular interlacement of
these fibres, which adds to the toughness, but reduces the
cleavability of the wood. At the juncture of the limb and stem the
fibres on the upper and lower sides of the limb behave differently.
On the lower side they run from the stem into the limb, forming an
uninterrupted strand or tissue and a perfect union. On the upper side
the fibres bend aside, are not continuous into the limb, and hence the
connection is not perfect (see Fig. 18). Owing to this arrangement of
the fibres, the cleft made in splitting never runs into the knot if
started on the side above the limb, but is apt to enter the knot if
started below, a fact well understood in woodcraft. When limbs die,
decay, and break off, the remaining stubs are surrounded, and may
finally be covered by the growth of the trunk and thus give rise to
the annoying "dead" or "loose" knots.

[Illustration: Fig. 18. Section of Wood showing Position of
the Grain at Base of a Limb. P, pith of both stem and limb;
1-7, seven yearly layers of wood; _a_, _b_, knot or basal
part of a limb which lived for four years, then died and
broke off near the stem, leaving the part to the left of _a_,
_b_, a "sound" knot, the part to the right a "dead" knot,
which would soon be entirely covered by the growing stem.]

COLOR AND ODOR OF WOOD

Color, like structure, lends beauty to the wood, aids in its
identification, and is of great value in the determination of its
quality. If we consider only the heartwood, the black color of the
persimmon, the dark brown of the walnut, the light brown of the white
oaks, the reddish brown of the red oaks, the yellowish white of the
tulip and poplars, the brownish red of the redwood and cedars, the
yellow of the papaw and sumac, are all reliable marks of distinction
and color. Together with luster and weight, they are only too often
the only features depended upon in practice. Newly formed wood, like
that of the outer few rings, has but little color. The sapwood
generally is light, and the wo