42 GUIDE TO TIMBERS OF NIGERIA 



sent by the Government of Nigeria (Empire Timber Exhibi- 

 tion, 1920). Our specimen No. 2763 HS. " Ochwen " from 

 South Nigeria agrees, but No. 2848 " Akpwania," from the 

 same colony, does not. 



GENERAL CHARACTERS. A comparatively light and rather 

 soft wood of a light brown colour striped light and dark, the 

 difference in the shade being due partly to bands of varying 

 density and partly to cross-grain. Some feather-like tracery 

 is to be seen on the tangential section, but it is not very pro- 

 minent. Grain, coarse, open, slightly inclined. Transverse 

 section darker in shade than the others. Not cold to the 

 touch, nor likely to soil. Smell, none. Unwin says (1920, 

 pp. 68 and 277), " Very pretty grain . . . with almost evenly 

 distributed streaks of darker brown." 



STRUCTURE. Resembles that of Afzelia africana No. 3102 

 of this series, p. 37. 



Transverse section. (Prepared with glass-paper.) See PL III, 

 fig. 2. Parenchyma of two kinds : (a) vasicentric and (c) 

 simulating the ring-boundaries. 



Parenchyma (a) easily visible to the unaided eye, giving the 

 light tone to the section ; sheathes the pores, forming broad 

 patches of a rhomboidal or lozenge shape and joining 2-5 

 pores or pore-groups. The lines which join the pores are 

 more concentric than oblique. Proportion of the wood, about 

 one-fifth. 



Parenchyma (c) in fine concentric lines that are visible to 

 the unaided eye. They are sometimes repeated and are more 

 continuous in the denser zones that are poor in pores. Colour 

 lighter than that of the rays ; width about that of the intervals 

 between the rays. 



Vessels very easily visible as perforations, large, uniformly 

 distributed (except in the dense zones) ; widely isolated, 0-3 

 per sq. mm. Arranged in oblique lines as already stated. 

 Simple and in both nested and radial groups of 2-8, three 

 frequent. Contents, a light -coloured amorphous substance, 

 little if any gum or resin, but certain dried-up brown 

 masses. 



Rays not too easily visible with lens, very fine ; of one kind ; 

 colour brown between that of the P. (a) and that of the ground. 

 Very regular in size, but less so in spacing, at intervals equal 



