22 GUIDE TO TIMBERS OF NIGERIA 



extending to wings, colour pale buff ; proportion of the wood 

 about one-fifth. 



Vessels not visible except by means of their parenchyma ; 

 medium in size ; very irregular in distribution, being more or 

 less crowded in some parts and widely isolated in others ; 

 arrangement indefinite for the most part, but straggling, oblique, 

 or serpentine lines may be discerned here and there. Number 

 per mm. 6-14. Shape distinctly oval ; some globules of resin. 



Rays visible only with. the lens, very weak and fine ; of one 

 kind ; regular in size and spacing and at intervals of about 

 three times their own width ; number per mm. 10-14. Con- 

 tents red, giving the rays that colour. Proportion of the wood 

 nearly one-third. 



Ground-tissue-cells visible ini places with the macroscope ; 

 proportion of the wood about one-half. 



Rings apparently traceable, but very doubtful, the zones of 

 denser tissue may indicate the boundaries ; contour very 

 irregular. 



Radial section very uniform in colour, relieved a little by 

 the slightly lighter parenchyma. Grain, open, empty ; (the 

 scalariform perforations of the vessels are readily visible with 

 the macroscope, or even with a hand -lens). Parenchyma visible 

 as hoary borders. Rays just visible by their darker red 

 colour. Rings not indicated except by a faint striping. 



Tangential section as the radial, but the rays are minute 

 spindle-shaped lines of a distinctly red colour, not in parallel, 

 being exceedingly irregularly distributed, multi -seriate, but 

 not exceeding three rows of cells ; height up to about 15 cells. 



Pith ? Sapwood not defined from the heartwood. Unwin 

 says (I.e. p. 405), " slash red ; sapwood very narrow, yellowish- 

 red." 



BARK entire, falling away at length in very small scales ; 

 colour silvery-grey, and of a rusty reddish brown (burnt sienna) 

 within. Lenticels roundish with horizontal fissures, rather 

 scarce and widely isolated. Texture exceedingly fibrous and 

 coarse, the various layers of fibres being strongly inclined to 

 each other. Fairly strongly adherent to the trunk. Bark in 

 s< < t ion of one layer and the epidermis ; colour uniformly brown ; 

 scleroses small but very abundant (about half the substance) ; 

 whitish. Weathers lighter brown. 



