20 
A. S. Marsh. 
contains the numerous bundles which supply the leaves. Just 
outside the stele the general parenchyma shows peculiar patches of 
tissue which, without having any obvious histological difference 
from the rest of the cortex, takes up rather more stain and which 
always remained cloudy in the cleared preparations made in 
investigating the course of the leaf-trace bundles (“ cloudy tissue” 
of Fig. 1*). 
In the main part of the stem, as described above, the cambium 
extends beyond each bundle laterally but is not continued unbroken 
all the way round. At the base of the stem, however, the cambium 
is continuous and the groups of tracheids are much fewer in number, 
much broader and extend further towards the centre of the stem. 
From this we pass to the root which has a tetrarch structure with 
continuous cambium and broad wedges of secondary wood opposite 
the phloem groups (see diagram Fig. 1). 
The wood in the stem shows no sharp differentiation into 
primary and secondary portions, as except for the few small annular 
protoxylem elements, the whole of the wood is composed of 
tracheids, generally hexagonal in cross section, with a rather open 
type of scalariform pitting (see Fig. 7). The tracheids may even 
appear annular or slightly reticulate rather than scalariform. No 
trace of ordinary bordered pitting was found anywhere in the plant. 
The stem wood is uniformly endarch and no trace could be 
seen of medullary bundles or of accessory zones (“ abnormal zones ”) 
described in many Cycads. 
The Girdle System. 
This was investigated by cutting thick sections (about 3 mm.) 
and clearing them with Eau de Javelle. They were then stained 
with fuchsin, washed first with dilute acetic acid and then with 
water, taken through increasing strengths of alcohol and finally 
cleared with xylol. In this way it was possible to trace with great 
accuracy the course of the bundles supplying each leaf-base. 
Stangeria shows an interesting variation from the normal type 
of Cycad girdle-trace. Ten leaf-supplies were traced through the 
cortex and eight of these were found to consist of a typical girdle, 
plus four strands running directly from the main ring to the leaf- 
base (Figs. 2 and 3). There are thus six main strands supplying 
the leaf, but each of these may branch at any point, though often 
a bundle branches only for the two resultant strands to reunite. 
At the base of the leaf (usually difficult to see when the leaf has 
fallen and the stem has swollen by growth) is a complex system of 
