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:
I. WOODS WITHOUT PORES--CONIFERS OR SO-CALLED "SOFTWOODS"
1. Pines. Fig. 144. Resin ducts numerous, prominent, fairly evenly distributed. Wood often pitchy. Resinous odor distinct. Clear demarcation between heart and sapwood. There are two groups of pines--soft and hard.
(a) Soft Pines. Wood light, soft, not strong, even-textured, very easy to work. Change from early wood to late wood is gradual and the difference in density is not great.
(b) Hard Pines. Wood variable but typically rather heavy, hard and strong, uneven textured, fairly easy to work. Change from early wood to late wood is abrupt and the difference in density and color is very marked, consequently alternate layers of light and dark wood show. The wood of nearly all pines is very extensively employed in construction work and in general carpentry.
2. Douglas fir. Resin ducts less numerous and conspicuous than in the pines, irregularly distributed, often in small groups. Odorless or nearly so. Heartwood and sapwood distinct. The wood is of two kinds. In one the growth rings are narrow and the wood is rather light and soft, easy to work, reddish yellow in color; in the other the growth rings are wide, the wood is rather hard to work, as there is great contrast between the weak early wood and the very dense late wood of the annual rings.