THE STRUCTURE OF WOOD. 



81 



In the radial section, Fig. 21 : 



(6) The pith rays are evident. In sycamore, Xo. 53, Chap. Ill, 

 they are quite large. 



(7) The interweaving of the fibers is to be noted and also their 

 varietv. 



PITH RAYS' 



CROSS-SECTION 



JTH RAYS 



196 DIAMETERS 



RADIAL 5EXTIOn 



37 DIAMETERS 



-POROUS WOOD CYELLOW POPLAR) 



Fig. 21. 



In the tangential section, Fig. 21 : 



(8) The grain is to be traced only dimly, but the fibers are seen 

 to run in waves around the pith rays. 



(9) The pith rays, the ends of which are plainly visible. 



