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OAK TIMBER.
137
Medullary rays of two kinds, a smaller number of very broad, shining ones, from ½ to 1 mm., or even a centimetre or more apart, and very numerous (about
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/The_Oak_%28Marshall_Ward%29_Fig_38.jpg/250px-The_Oak_%28Marshall_Ward%29_Fig_38.jpg)
Fig. 38.—Transverse section of wood of oak (magnified five diameters), showing five annual rings, as denoted by the large vessels of the spring wood; the vessels become smaller in the summer and autumn wood, and are arranged in tongue-like groups. Nine broad medullary rays are shown, the rest are very narrow (cf. Fig. 27). The rest of the section is filled with tracheids, fibers, and wood-parenchyma. (Müller.)