210 Lang . — Studies in the Morphology and 
trace arises from the stele to one side of the position of the gap, followed by 
a second from the other side of the stele. The next leaf-gap opens in the 
xylem ring and a small trace departs. The endodermal relations at this and 
the succeeding leaf-gaps are of the adult type, in that a gap remains for some 
distance in the endodermis, the edges of the 
latter being continued round for a short dis- 
tance. After the trace has separated from 
the stele a root arises from the latter to one 
side of the gap. It is unnecessary to follow 
this plant node by node, as the relations are 
evident from the reconstruction. The stele 
is relatively bulky and the primary xylem 
thick, the same type of leaf-trace departure 
is maintained, and shortly after the separation 
of each trace one or two root-traces arise 
from the stele. There is thus evident a 
certain segmental regularity in the relations 
of roots and leaves, which is also shown more 
or less distinctly in the other plants. 
In plant C (Text-fig. 5) the solid xylem 
strand increases in diameter and bears several 
root- traces. About the level of the fourth 
root parenchyma appears in the centre of the 
stele and is continuous with the outer con- 
junctive parenchyma of the stele at what 
must probably be regarded as the first leaf- 
gap, although no leaf-trace passes off. Above 
this the xylem of the medullated stele is 
again completed, and two root-traces pass 
off. The leaf-trace which passes off from 
the second leaf-gap dies out in the cortex, 
while the third trace reaches a leaf. The 
endodermis is completed preparatory to the 
departure of both these traces. The third 
gap in the xylem remains open for some 
distance, and when it closes preparations 
Text-fig. 5. Reconstruction of for the fourth leaf-trace are evident. The 
t ‘“ ofpIant C> Desoription in departure of this trace is very gradual and 
the leaf-gap is correspondingly elongated. 
Before any interruption of the external endodermis an incomplete internal 
endodermis appears. This forms two strips extending from either side of 
the incipient trace ; on the separation of the latter the internal endodermis 
becomes continuous on either side with the margins of the gap in the 
