THE TIMBERS OF COMMERCE 



soft-tissue, the cells of which are nearly half the pore- diameter : 

 mostly single, but also in groups of 2-3 pores. 



Rays. Visible in certain lights : size 4, medium : nearly 

 uniform : equidistant, a pore-width or less apart : few, about 

 2 per mm. : less dense than the ground-tissue : undulating, but 

 not avoiding the pores : tapering both ends : the attenuated 

 ends convey the impression that there are two kinds of rays, a 

 circumstance of frequent occurrence in this order (Celastrinese). 



Rings. Not very clear : boundary, a narrow ring of pore-less 

 Autumn wood adjoining a more porous band of Spring wood : 

 contour rounded or undulating (80 per inch in my specimen). 



Soft-tissue. Abundant in many long, radial lines of cells 

 and also in ill-defined, gently undulating, concentric bands. 



Pith. ? 

 ' Radial Section. Rather lighter in shade than the transverse. 

 The pores need the lens and are minute shining lines : the 

 rays are inconspicuous flakes of almost the same colour as the 

 ground-tissue and visible in certain lights only : the rings and 

 the soft-tissue can neither be traced with the lens. 



Tangential Section. As the Radial, but unusually uniform 

 in colour : the rays need the lens, being minute, dark-red lines 

 about o - 5 mm. high. 



Type specimens authenticated by the Forest Officer to the 

 Government of Natal. They do not agree with Laslett's de- 

 scription " something like walnut," but I have checked them 

 with specimens at Kew, the Imperial Institute and elsewhere, 

 and with Nordlinger's section. 



No. 41. SILKBARK. Celastrus acuminatus. 

 Linn. 



(Not of Rafin., or Wall.) 

 Plate IV. Fig. 30. 



Natural Order. Celastrinese. 



Alternative Name. Zybast (57). 



Source of Supply. South Africa. 



Physical Characters, etc. Recorded dry-weight 63 lb. per 

 cu. ft. Hardness Grade 3, compare Blackthorn. Taste or 

 smell none. Burns well and quietly without aroma, heat 

 expels a yellow juice, embers glow in still air and consume very 

 slowly to the abundant white ash. Solution faint pinkish- 

 brown, deepening to port wine colour upon the addition of 

 potash ; no ppt. 



Grain, Unusually fine, compact and dense. Surface rather 

 dull, but silky and smooth to the touch. 



Bar k. ? 



48 



