Boodle . — Anatomy of the Schizaeaceae . 367 
about one inch) it has a well-marked prominence on the morpho- 
logically lower side, while the outline of the xylem on the 
upper side is rounded, and the two lateral prominences are 
broad but only slightly raised. At a still higher level the 
xylem becomes three-lobed, much as in Fig. 4. In this upper 
region of the petiole spiral tracheides occur in connexion with 
all three prominences ; one group near the lower corner of 
each lateral prominence, and one near each corner of the 
lower one. Towards the lower region of the petiole the two 
groups of spiral tracheides belonging to the lower side of the 
xylem are retained, but the other groups disappear, all the 
small peripheral tracheides of the lateral prominences being 
then scalariform. At a lower level still, close to the base 
of the petiole, spiral elements are absent altogether. The 
lower prominence is no longer broad and flattened, but forms 
a slight rounded angle with a single group of small scalariform 
protoxylem-elements forming its apex. This group becomes 
less and less marked as one passes downwards, so that the 
leaf-trace in passing through the cortex of the stem has 
a xylem of circular and then oval outline, and a nearly 
uniform layer of phloem surrounding the xylem. The 
position of the lower group of scalariform tracheides is still 
just distinguishable, and one is able to determine that the 
bundle does not undergo any great change in orientation 
during its passage through the cortex. The xylem of the 
leaf-trace passes in about radially until it is almost touching 
the stele, when it curves downwards and its tracheides join 
those of the stele. As stated above, there has been no 
important change in orientation, so the lower group of 
scalariform tracheides is probably continuous with some of 
the protoxylem-elements of the stele, though this cannot 
be stated with certainty. The node in longitudinal section 
shows a peculiar structure. A large number of branched 
tracheides occur, chiefly of a V- or Y-shape 1 . They are 
arranged one above another and more or less fitting into 
one another, and are so placed that one arm of each tracheide 
1 A few similar tracheides occur at the node in Trichomanes radicans. 
