518 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou. VIII. 
the internal endodermis shows a constant tendency to dip outward into 
the leaf-gaps and at times in the adult so far as to reach the external 
endodermis (Fig. 11). 
Another striking phenomenon is the eccentric position of the internal 
endodermis in its initial stages. Not only is it eccentric, but it originates 
at the inner entrance to a gap that marks a separating leaf-trace (Fig. 4). 
Such a position and mode of origin of endodermal pockets are so common 
in filicinean steles with pith admittedly of extrastelar homologies that 
their occurrence in Osmunda is of more than passing interest. 
The first-formed leaf-traces are collateral, the rest are concentric. 
The ‘‘quergestreckte Zellen’’ of Zenetti or tangentially elongated peri- 
pheral phloem cells of the stem are not present in the seedling. They 
begin to appear later, that is when there is a more frequent overlapping of 
the leaf-gaps than maintains in the seedling. The phloem on the inner 
face of the leaf-trace is throughout in continuity with the phloem that 
surrounds the xylem of the stem. It has been held by Tansley that this 
argues against the view that the primitive siphonostele was amphiphloic, 
but this seems to be making a far-fetched application of the textural 
continuity of like tissues. This view was bound up with another for which 
I can also see no adequate justification, namely, that a reduction of the 
cauline stele would mean a reduction of the leaf-trace. 
The stipule-like wings on the petioles are very striking in the leaves 
of the seedling; sometimes they are so broad as to reach more than half 
way around the stock (Fig. 6). 
SPECIFIC EXAMPLES: 
A.—A little above the foot, and opposite to it the cotyledonary 
trace separates from the cauline stele, and almost at the same time, and 
go° around from it the first root. The first four leaves are arranged 
bilaterally on the stem. ‘The same is also true of the roots except that the 
fourth root accompanies the fifth leaf-trace. With the fifth trace is initiat- 
ed the 34 arrangement. Up to the sixth leaf-trace the stele is not affected 
by the foliar traces, but preliminary to the segmentation of the sixth 
leaf-trace, a pocket of three parenchyma cells appears. Above, there is a 
Wide bay occupied by from three to five cells surrounded by a curved 
line of tracheids. ‘The ends of the crescent close around a pith of eight 
cells. This pith almost immediately disappears, and is not re-formed at. 
the next node. 
