DISTINGUISHING FEATURES. 



61 



of the ring. The proportion of each and the manner in which the one 

 merges into the other are sometimes used, but more frequently the 

 manner in which the pores appear distributed in either. 



Fig. 38. — " Ring-porous " woods — white oak and hickory, a.r., annual ring; su. w., summer wood; 

 8}). «>., spring wood; v, vessels or pores ; c. I., "concentric" lines; rt, darker tracts of hard fibers form- 

 ing the firm part of oak wood; pr, pith rays. 



(4) Pores, which are vessels cut through, appearing as holes in cross 

 section, in longitudinal section as channels, scratches, or indentations. 

 (See p. 19 and figs. 38 and 39.) They appear only in the broad-leaved, 

 so called, hard woods; their relative size (large, medium, small, minute, 

 and indistinct, when they cease to be visible individually by the naked 

 eye) and manner of distribution in the ring being of much importance, 

 and especially in the summer wood, where they appear singly, in groups, 

 or short broken lines, in continuous concentric, often wavy, lines, or in 

 radial branching lines. 



(5) Eesin ducts (see p. 16 and fig. 37), which appear very much like 

 pores in cross section, namely, as holes or lighter or darker colored 

 dots, but much more scattered. They occur only in coniferous woods, 

 and their presence or absence, size, number, and distribution are an 

 important distinction in these woods. 



ar 



Beech ! Sycamore I Birch. 



Fig. 39.— "Diffuse-poroua ' ' •woods, ar, annual ring ; pr, pith rays which are ' ' broad " at a, " fine " at 



b, "indistinct" at d. 



(6) Pith rays(seep.l7 and figs. 38 and 39), which in cross section appear 

 as radial lines, and in radial section as interrupted bands of varying 

 breadth, impart a peculiar luster to that section in some woods. They 

 are most readily visible with the naked eye or with a magnifier in the 



