9o6 



A TEXTBOOK OF THEORETICAL BOTANY 



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Fig. 889. — Fraximis excelsior. Ring-porous 

 wood. Transverse section of the 

 secondary wood showing the con- 

 centration of vessels at the inner margin 

 of each annual ring. 



sempervirens. Diffuse- 

 Transverse section of 

 the secondary wood showing the 

 diffuse distribution of vessels. 



Fig. 890. — Bu.xus 

 porous wood. 



