ood fibre or
tracheids proper, but the cells of the intermediate rows in the rays
of cedars, etc., have only "simple" pits, _i.e._, pits devoid of the
saucer-like "border" or rim. In pine, many of the pith rays are larger
than the majority, each containing a whitish line, the horizontal
resin duct, which, though much smaller, resembles the vertical ducts
on the cross-section. The larger vertical resin ducts are best
observed on removal of the bark from a fresh piece of white pine cut
in the winter where they appear as conspicuous white lines, extending
often for many inches up and down the stem. Neither the horizontal nor
the vertical resin ducts are vessels or cells, but are openings
between cells, _i.e._, intercellular spaces, in which the resin
accumulates, freely oozing out when the ducts of a fresh piece of
sapwood are cut. They are present only in our coniferous woods, and
even here they are restricted to pine, spruce, and larch, and are
normally absent in fir, cedar, cypress, and yew. Altogether, the
structure of coniferous woods is very simple and regular, the bulk
being made up of the small fibres called tracheids, the disturbing
elements of pith rays and resin ducts being insignificant, and hence
the great uniformity and great technical value of coniferous woods.

LIST OF IMPORTANT CONIFEROUS WOODS

CEDAR

Light soft, stiff, not strong, of fine texture. Sap- and heartwood
distinct, the former lighter, the latter a dull grayish brown or red.
The wood seasons rapidly, shrinks and checks but little, and is very
durable in contact with the soil. Used like soft pine, but owing to
its great durability preferred for shingles, etc. Cedars usually occur
scattered, but they form in certain localities forests of considerable
extent.

(_a_) White Cedars

=1. White Cedar= (_Thuya occidentalis_) (Arborvitae, Tree of Life).
Heartwood light yellowish brown, sapwood nearly white. Wood light,
soft, not strong, of fine texture, very durable in contact with the
soil, very fragrant. Scattered along streams and lakes, frequently
covering extensive swamps; rarely large enough for lumber, but
commonly used for fence posts, rails, railway ties, and shingles. This
species has been extensively cultivated as an ornamental tree for at
least a century. Maine to Minnesota and northward.

=2. Canoe Cedar= (_Thuya gigantea_) (Red Cedar of the West).