722 
DR JOHN M‘LEAN THOMPSON ON NEW STELAR FACTS, 
leaf-traces, in others through xylic gaps with which leaf-traces are not associated. 
But the features to which special attention would he drawn occur between levels I 
and II. Between these lies an isolated endo- 
dermal spindle, while within the base of a pocket 
is a chain of tracheides — here represented as a 
black line (T). On the theory of cortical origin 
of pith, tracheides would not be expected to figure 
among the contents of a closed endodermal 
pocket. In fig. 16 the stelar structure at the 
base of the endodermal spindle is shown. The 
xylem is dictyoxylic, and to the inside of the 
narrower xylic gap is an endodermal cell (En.), 
which is the base of the spindle. Fig. 17 repre- 
sents the structure at a slightly higher level. 
The xylic gaps have closed, and the endodermal 
spindle is here tubular (En.). In fig. 18 the apex 
of the spindle is reached (En.). At En.' is an 
almost basal section of the pocket from the axil of 
II leaf- trace a, at En" is a section towards the base 
of the pocket associated with leaf-trace b. It 
contains a mature tracheid. The details of this 
pocket are shown on a larger scale in fig. 19. 
The endodermis is a complete ring, and contains 
a parenchymatous cell (P) and a tracheid (T). 
Fig. 20 shows the structure of the pocket at a 
slightly lower level. The endodermis here sur- 
rounds two parenchymatous cells, and a tracheid 
forms part of the endodermal ring. The actual 
base of the pocket is shown in fig. 21. It com- 
prises six endodermal cells, and partly involves 
a tracheid. Tracheides of the xylem-cylinder are 
close at hand (T'). Followed down into a lower 
section (fig. 22), the tracheid in fig. 21 (T) consorts 
with other tracheides which lie in the parenchy- 
matous selvage. An inclusion of tracheides in 
endodermal cells has been observed in another 
stem. In this case the endodermis was an. iso- 
lated spindle situated in the sclerotic pith. Fig. 23 shows a section through the 
base of this spindle. The endodermal cells surround a single tracheid (T). Fig. 24 
is from a section of the spindle at a higher level ; the endodermal ring (En.) is entirely 
filled with tracheids. From these facts it may be concluded that by static change 
