486 
Tansley and Lnlham. — A Study of the 
Plant E had most of its leaves broken off. The one nearest the apex 
(Fig. 5) was considerably larger and more complex than any we have 
yet met. 
A transverse section of the proximal end of the rhizome (Fig. 16) 
shows a state of things rather different from any we have hitherto seen. 
While in D there is present an internal endodermis (either in the form 
of scattered endodermal cells or of a strand having a crescentic section) not 
associated with ground-tissue-pith (‘ internal cortex 1 of Van Tieghem and 
Jeffrey), together with an internal ridge or strand of xylem, in the present 
case there is an internal endodermis enclosing a ground-tissue paren- 
chymatous pith of about twenty cells ; we have, in fact, a simple solenostele 
with a comparatively slight local internal dilatation of the xylem-ring. 
The first leaf-trace goes off gradually, apparently in the form of a closed 
cylinder. The pith included within this ring almost certainly communicates 
with that of the stele, though the connexion was not actually seen. There 
is no leaf- gap. A group of small tracheids (not spiral) occurs in the middle 
of the abaxial side of the trace. After the departure of the first trace 
the internal xylem-dilatation becomes more marked. The second leaf-trace 
goes off like the first. The connexion of its pith with that of the stele 
is here indubitable. There is no leaf-gap, but the xylem of the trace 
is interrupted by the junction of the external with the internal endodermis 
of the trace, at the point corresponding with the opening in the horseshoe 
type of trace. 
The internal xylem ridge now becomes cut off from the ring by an 
extension of the internal phloem. It runs past the third node without joining 
the external xylem. This is the first instance of such a behaviour in this 
species, a behaviour which is quite exceptional, but which we have found in 
one case in the relation of the third cylinder to the second in the adult 
plant 1 . The internal endodermis also extends at the node itself round the 
internal strand, but immediately afterwards the latter rejoins the external 
xylem, and at the point of junction tracheids are seen running from the 
central strand to the point from which the trace has just departed. In the 
course of the next internode the xylem of the central strand again becomes 
separated from the external xylem by an extension of the phloem. Soon, 
however, the junction of the xylem is re-effected, and this is maintained 
through the fourth node. The fourth leaf-trace goes off similarly to the 
third. The fifth trace now follows on the other side. It goes off almost 
perpendicularly to the axis of the stele, is considerably bulkier than the 
preceding traces, and is the first which makes a definite gap in the stele, so 
that the ground-tissue of the cortex comes into connexion with that of the 
pith (Fig. 1 7). This gap, however, is very short, i. e. it does not extend in 
front of the base of the leaf-trace (Fig. 18). Immediately after the closure 
1 Seward (’99), p. 186, also records such a case. 
