20 GUIDE TO TIMBERS OF NIGERIA 



Parenchyma (a) in very small quantity sheathing the ves- 

 sels : white. 



Vessels readily visible as perforations, very large but varying 

 greatly in size and numbers, the larger being apparently on 

 the inner edge of the ring. Number per sq. mm. 0-5. Arrange- 

 ment indefinite, but in zones here and there. Simple for the 

 most part, but there are (radial) groups of as many as 4. 

 Shape, oval. Contents, shining yellow tyloses. Proportion of 

 the mass of the area of the section (including parenchyma) 

 scarcely more than one-twentieth. 



Rays visible as fine white lines, somewhat irregular in size, 

 and in spacing, rather less than a pore- width apart, but having 

 numerous fine ends between the thicker middles ; very slightly 

 avoiding the pores ; number per mm. 4-8. Proportion of the 

 mass of the wood, nearly half. 



Ground-tissue-cells very large and visible with a good hand- 

 lens. Proportion of the mass of the wood, about |. Cells 

 very variable in size. 



Rings extremely indefinite ; apparently clear to the naked 

 eye, but little if any indication of true boundaries when magni- 

 fied. 



Radial section. Colour, buff, mottled with a small pretty 

 silver-grain. Grain, very coarse, the pores occasionally filled 

 with large shining yellow tyloses ; the loculi of the vessels are 

 about as broad as long. Parenchyma just visible with lens as 

 very narrow, hoary borders. Rays as above covering about 

 half the surface ; height up to 2-5 mm. Rings not defined, but 

 dusky bands sometimes prominent. 



There is a tissue indicated by numerous fine white lines, which 

 evidently represent uni-cellular strata in a horizontal plane, as 

 they are traceable continuously from one section to another, 

 having the same appearance on all vertical sections. They 

 are not apparent on the transverse section. These will be the 

 subject of further investigation. 



Tangential section as the radial, but the rays are very obscure 

 and dull, being just visible by reflected light as small white 

 spindle-shaped lines producing a matt effect; width up to 

 four cells. 



nth? Sapwood? 



Density, No. 8017, 0-405 or about 25-6 Ib. per cu. ft. 



