Usually the word grain means the pattern or "figure" formed by the distinction between the spring wood and the summer wood. If the annual rings are wide, the wood is, in common usage, called "coarse grained," if narrow, "fine grained," so that of two trees of the same species, one may be coarse grained and the other fine grained, depending solely on the accident of fast or slow growth. The terms coarse grain and fine grain are also frequently used to distinguish such ring-porous woods as have large prominent pores, like chestnut and ash, from those having small or no pores, as cherry and lignum vitae. A better expression in this case would be coarse and fine textured. When such coarse textured woods are stained, the large pores in the spring wood absorb more stain than the smaller elements in the summer wood, and hence the former part appears darker. In the "fine grained" (or better, fine textured,) woods the pores are absent or are small and scattered, and the wood is hard, so that they are capable of taking a high polish. This indicates the meaning of the words coarse and fine in the mind of the cabinet-maker, the reference being primarily to texture. If the elements of which a wood are composed are of approximately uniform size, it would be said to have a uniform texture, as in white pine, while uniform grain would mean, that the elements, tho of varying sizes, were evenly distributed, as in the diffuse-porous woods. The term "grain" also refers to the regularity of the wood structure. An ideal tree would be composed of a succession of regular cones, but few trees are truly circular in cross-section and even in those that are circular, the pith is rarely in the center, showing that one side of the tree, usually the south side, is better nourished than the other, Fig. 14, p. 23. The normal direction of the fibers of wood is parallel to the axis of the stem in which they grow. Such wood is called "straight-grained," Fig. 22, but there are many deviations from this rule. Whenever the grain of the wood in a board is, in whole or in part, oblique to the sides of the board, it is called "cross-grained." An illustration of this is a bend in the fibers, due to a bend in the whole tree or to the presence of a neighboring knot. This bend makes the board more difficult to plane. In many cases, probably in more cases than not, the wood fibers twist around the tree. (See some of the logs in Fig. 107, p. 254.) This produces "spiral" or "twisted" grain. [Illustration: Fig. 22. Straight Grained Long-leaf Pine (full size).]