339 
Phylloglossum Drummondii . 
leaves of Phylloglossum are thus anatomically microphyllous, so to speak, 
and may be compared usefully with Isoetes in this regard—the leaves in 
both being large as compared with the stem, although detailed examination 
reveals them, in both cases, to be characteristically microphyllous in their 
behaviour to the stele. 
At a level where the three leaf-traces, corresponding to the three root- 
traces first observed, have progressed outwards to about midway in the 
cortex, the transverse section presents the appearance shown in Fig. 5. The 
leaf-traces are mesarch, the protoxylem in many cases being represented 
by cavities (see posted). 
Fig. 6. Showing the U-shaped stele, with protoxylem-cavities. The strand of the young tuber 
has broken away from the stele, and is dying out. Five leaves appear, each with a single, small 
central vascular strand. There are no leaf-traces in this region : no more foliage leaves emerge. 
The central stele is here similar to that seen in many of the Lyco- 
podiales. The xylem-strand of the young tuber stalk has joined this main 
stele, which is a more or less continuous band of xylem enclosing a paren¬ 
chymatous ‘ pith and is roughly pentagonal. This is noticeably like 
P silo turn and many of the fossil Lepidodendra. 
This condition, however, does not persist for any appreciable length of 
the stem ; a little further up there is a distinct break in the xylem-band, on 
the side occupied, in sections at a lower level, by the young tuber. The 
stele thus becomes horseshoe-shaped ; and although there seems to be 
a tendency to bridge over this gap, at first, by weakly developed tracheides, 
the gap may be said, approximately speaking, to persist until the base of 
z 2, 
