OUR COMMON WOODS 



221 



very sharp knife; a dull one will tear and break the cells 

 so that the structure becomes obscured. With any good 

 hand lens a great many details will then appear which 

 before were not visible. In the case of some woods like oak, 

 ash, and chestnut, it will be found that the early wood 

 contains many compara- 

 tively large openings, 

 called pores, as shown 

 in Figs. 146 and 147. 

 Pores are cross-sections 

 of vessels which are little 

 tube-like elements run- 

 ning throughout the tree. 

 The vessels are water 

 carriers. A wood with 

 its large pores collected 

 into one row or in a 

 single band is said to be 

 ring-porous. Fig. 146 

 shows such an arrange- 

 ment. A wood with its 

 pores scattered through- 

 out the year's growth 

 instead of collected in a 

 ring is diffuse-porous. 

 Maple, as shown in Fig. 

 152, is of this character. 



All of our broadleaf 

 woods are either ring-porous or diffuse-porous, though 

 some of them, like the walnut, are nearly half way be- 

 tween the two groups. 



If the wood of hickory, for example, be examined with 

 the magnifying lens, it will be seen that there are numerous 



^ 



tsmisii^ 



ij 



Fig. 147. — Example of the Bla^k Oak 

 Group. (Querciis coccinea.) 

 (Magnified 20 times.) 



