366 
DR JOHN M‘LEAN THOMPSON ON THE 
and the parenchyma is maintained in contact with the stele throughout the entire 
axis. The undivided leaf-trace is inserted on the stele at or near the base of the 
leaf-gap, and the root-traces originate singly below the leaf-gaps or near their 
margins (figs. 4, 6, and text-figs. 1, 2). 
The anatomical condition described is typical of the axis as a whole, and is in 
close agreement with that of J. verticalis. _ A reconstruction of the stele based on a 
long series of sections of the axis is given in fig. 4. The conclusions arrived at 
from serial sections are, that the vascular system is a slender solenostele, that the 
undivided leaf-traces depart at or near the base of the gaps, and that the root-traces 
originate singly on the general stelar surface. 
Text-fig. 2. 
Externally the branching of the axis may appear dichotomous, but the vascular 
supplies to the branches have never been found to be identical. The stelar recon-, 
struction of a typical branching is shown in fig. 6. It will be seen from this and 
from the group of diagrams (a)-(j) composing text-fig. 2, and illustrating steps in this 
branching, that the products of division of the original solenostele are two dissimilar 
solenosteles. Of these the right-hand member bears a leaf-trace towards its base, 
but neither leaf-gap nor leaf-trace is shown on the left-hand branch. That this is 
the normal condition in stelar-branching follows reasonably from the varying lengths 
and overlappings of the leaf-gaps in the undivided portion of the axis. 
Root . — A transverse section of a root is shown in fig. 8. The stele is small, and 
the cortical layer external to the endodermis has strongly thickened walls. The 
general structure is typical of roots of xerophilous Ferns, and supplies no features 
which can be used in a phyletic discussion. 
