OAK TIMBER 



137 



Medullary rays of two kinds, a smaller number of 

 very broad, shining ones, from ^ to 1 mm., or even a 

 centimetre or more apart, and very numerous (about 



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, fibres, and wood- 

 parenchyma. (Miiller.) 



