PLATE 3. EXOGENOUS STRUCTURE IN WOOD. 

 MEDULLARY OR PITH RAY. 



R 



T 



fettl, 



il fill 



HlwiiJwBHHtiUk?!-"":^"- 1 ' '' "" r '4 JOMfiiS 



miWiiiiijiiiiwu^ 



p 



Actual appearances of pith ray, PP. 

 P 



Microscopic enlargement of a tangential section of White Oak 

 showing large pith ray, pp. 



