GUIDE TO TIMBERS OF NIGERIA 39 



but then in fine lines about equal in width to one-quarter of 

 the diameter of a large pore. Proportion of the wood, about 

 one-third. 



Parenchyma (c) in very fine concentric lines, occasionally 

 repeated many times, which are just visible. The more con- 

 tinuous lines run in a zone which is poor in pores. Colour 

 similar to that of the rays ; width from that of a ray to twice 

 that width. In the middle zone of the ring these lines are 

 discontinuous and occur at irregular intervals. 



Vessels easily visible as perforations, large, uniformly dis- 

 tributed (except in the zone poor in pores), widely isolated, 

 5-7 per sq. mm., but areas of a sq. mm. without a pore. Some- 

 times in oblique lines united by P. (a). Often simple, but 

 mostly in nested groups, less frequently in radial groups, threes 

 are common and fours occur. Shape, oval ;" contents, white, 

 and a little red gum. 



Rays visible with difficulty with the unaided eye, but readily 

 with lens ; of one kind only ; colour yellow, slightly darker 

 than that of the P. (a) ; very regular in size and spacing, two 

 or three to the smaller diameter of a large pore ; 9-12 per 

 mm. Proportion of the wood, about J. 



Ground-tissue dense ; cells visible with the macroscope. 



Rings apparently well defined by the denser bands of wood ; 

 no certain boundary ; contour regular. 



Radial section. Surface clean with lighter and darker bands 

 of colour. Vessels very prominent, coarse, inclined, open, but 

 with an amorphous buff or white deposit here and there and 

 some red globules. 



Parenchyma (a) very distinct, giving the tone to the lighter 

 wood and appearing as borders and tails to the pores. P. (c) 

 visible with attention. Rays very fine, but yet visible by 

 their lustre as minute flecks. 



Tangential section as the radial, but the P. (a) broadens out 

 and forms a sort of " partridge-feather " design. The P. (c) 

 also appears quite distinctly. Rays just visible as a matt 

 effect and are individually visible with lens ; height about 

 eight to fourteen cells by one to two cells wide, the latter being 

 rare ; not in parallel. 



SAPWOOD " white " (Unwin, I.e.). " Yellowish-white " 

 (Comte de B., p. 151). 



