30 
WRIGHT : THE GENUS DIOSPYROS 
with unlike elements. When one end tapers the appearance 
is very similar to that of a short fibre. 
There is a little variation in the transverse, but consider¬ 
able in vertical dimensions throughout the species. In some 
species the relatively large transverse dimensions aid 
materially in distinguishing them in the wood of young 
twigs. 
The following are the dimensions of these elements 
in the sapwood of the respective species :— 
Species. 
Radial Diameter 
D. Ebenum 
mm. 
0*015 
mm. 
0*03 to 0*12 
D. quæsita 
... 
0*009 
0*04 to 0*15 
X). oocarpa 
0*013 
... 
0*06 to 0*13 
D. affinis 
0*016 
... 
0*09 
D. montana 
• • • 
0*02 
... 
0*07 to 0*20 
D. Embryopteris 
0*01 
0*09 to 0*13 
D. Moonii 
0*015 
... 
0*08 to 0*20 
D. attenuata 
0*014 
• • • 
0*08 to 0*18 
D. pruriens 
0*015 
... 
0*08 to 0*14 
D. acuta 
0*013 
0*09 to 0*15 
D. hirsuta 
... 
0*018 
... 
0*05 to 0*13 
D. Thwaitesii 
0*013 
... 
0*05 to 0*18 
D. crumenata 
0*016 
... 
0*06 to 0*12 
D. sylvatica 
0*014 
0*07 to 0*20 
D. Gardneri 
... 
0*016 
0*07 to 0*18 
D. oppositifolia 
0*014 
... 
0*08 to 0*13 
D. Melanoxylon 
0*017 
0*07 to 0*13 
D. ovalifolia 
0*011 
0*09 to 0*13 
D. Toposia 
0*013 
... 
0*06 to 0*15 
D. insignis 
0*014 
... 
0*06 to 0*19 
Length. 
Ths thickness of the wall varies from 0*001 to 0*0016 mm. 
These are the average radial dimensions and variations 
length of the wood parenchyma cells in the sapwood of 
the several species. The age of the trees and the climates 
under which they have grown are widely different, though 
the above does not show any remarkable variation. 
Wood Fibres .—These compose the greater part of the 
secondary xylem, and are responsible to a great extent for the 
durability of the timber. The occurrence in large numbers 
of these elements of great length, with thick walls and 
narrow lumina, enhances the value of any timber. 
