82 
A NOTE ON THE WOOD OF GNETUM GNEMON 
Unbranched latex tubes with brownish contents run perpendicularly through 
the pith, and lignified stellate cells are found in small numbers in the inter- 
node and abundantly in the node. 
Primary Wood. 
The young internode shows a ring of 27 to 29 vascular bundles with 
no sign of centripetal wood or transfusion tracheids. The number given 
for G. africanum 1 varies from 12 to 20. Spiral elements, some showing 
annular thickenings, and elements somewhat scalariform are present in 
the protbxylem (Plate VIII, fig. 1). In addition to these are some elements 
with a curious combination of scalariform thickening and bordered pits (fig. 2). 
Secondary Wood. 
The secondary wood consists of tracheids, vessels, lignified parenchyma 
and rays. 
Tracheids. The length of the tracheids is about 1 mm. Bordered pits 
are present on the radial and tangential walls, uniseriate in the majority of 
cases, biseriate in a few ; in the latter the pits of the two rows generally 
alternate. In all cases the pits are quite free from one another. The outline 
of the pit is circular, the mouth oblong, and the torus not well developed. 
This type of pore is described' 2 as being a vestige of the scalariform condition. 
The bordered pit differs thus from that of Ephedra, in which the mouth is 
described as round and the torus well developed. Bars of Sanio which are 
present in Ephedra are here most certainly absent from the great majority 
of tracheids, although in one or two there was just a suggestion of their 
presence. They are not mentioned as occurring in G. africanum. 
As in Ephedra tertiary spiral striations appear, but only once was 
anything seen — in a stained preparation — which might have been a resin- 
plate. Trabeculae were not found. 
In two cases a series of tracheids in tangential section showed cellulose 
transverse septa giving the appearance of tracheids becoming parenchyma, 
and bearing out Bailey’s 3 view that wood-parenchyma has been developed 
from tracheids. In one case a parenchymatous cell had been cut off from 
the end of a tracheid (fig. 3). 
Vessels. In the old wood the vessels are usually 3 or 4 times as wide 
as the tracheids, although some have about the same diameter as the larger 
tracheids. 
Multiseriate bordered pits, usually arranged irregularly, are present on 
the radial and tangential walls. The pits are quite free from one another, 
and occasionally fused pits are seen. Bars of Sanio and trabeculae which 
2 Thomson, 1913, p. 18. 3 Bailey, 1909, p. 231. 
i Duthie, 1912. 
