12 QUEBKACHO WOOD AND ITS SUBSTITUTES. 



Pores (vessels) larger (0.10 to 0.13 millimeters), closed (in the heart- 

 wood) and irregularly distributed, usually grouped in radial rows 

 of from two to four. Wood-parenchyma fibers confined to prox- 

 imity of vessels, often forming conspicuous groups. Wood fibers 

 very small in diameter (0.5 to 1.2 millimeters long). All cells of 

 the heartwood are crowded with a yellowish-brown substance. 

 Heartwood dark cherry-red, very hard, and heavy (about 78 

 pounds per cubic foot). 



(Quebrachia lorentzii Griseb.) 

 Approved : * 



JAMES WILSON, 



Secretary of Agriculture. 

 WASHINGTON, D. C. ; March 15, 1912. 



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