narrow and inconspicuous, and wood parenchyma is never prominent.
The woods of the pines, spruces, larches, and Douglas fir differ
from those of the other conifers in having _resin ducts_, Fig. 144.
In pines these are readily visible to the naked eye, appearing as
resinous dots on cross-sections and as pin scratches or dark lines
on longitudinal surfaces. The presence or absence of resin ducts is
a very important feature in identifying woods, hence it is very
important to make a careful search for them when they are not
readily visible.

How to identify a specimen of wood: The first thing to do in identifying
a piece of wood is to cut a smooth section at the end and note
(without the magnifier) the color, the prominence of the rays and
pores, and any other striking features. If the pores are readily
visible, the wood is from a broadleaf tree; if the large pores are
collected in a ring it belongs to the ring-porous division of the
broadleaf woods. If the rays are quite conspicuous and the wood is
hard and heavy, it is oak, as the key given later will show. Close
attention to the details of the key will enable one to decide to
what group of oaks it belongs.

In most cases the structure will not stand out so prominently as in
oak, so that it is necessary to make a careful study with the hand
lens. If pores appear, their arrangement, both in the early wood and
in the late wood, should be carefully noted; also whether the pores
are open or filled with a froth-like substance known as _tyloses_.
Wood parenchyma lines should be looked for, and if present, the
arrangement of the lines should be noted.

[Illustration: FIG. 148.--(Magnified about 8 times.)]

If no pores appear under the magnifying lens, look closely for resin
ducts. If these are found, note whether they are large or small,
numerous or scattered, open or closed, lighter or darker than the
wood. Note also whether the late wood is very heavy and hard,
showing a decided contrast to the early wood, or fairly soft and
grading into the early wood without abrupt change. Weigh the piece
in your hand, smell a fresh-cut surface to detect the odor, if any,
and taste a chip to see if anything characteristic is discoverable.
Then turn to the following key:

KEY

I. WOODS WITHOUT PORES--CONIFERS OR SO-CALLED "SOFTWOODS"

A. Woo