Boodle— Anatomy of the Schizaeaceae . 387 
in diameter ; it is thus much smaller than in A. mexicana , but 
has similar structural details. Fig. 41 is a diagram of the 
structure found just below the node. The inner and outer 
phloem are each represented by a ring of dots ; e. and i. e. are 
the outer and inner endodermis, separated in each case from 
the phloem by a wide layer of pericycle. The xylem-ring is 
bulged out on the right, preparatory to the separation of 
a leaf-trace, and e. is a group of three or four endodermal 
cells differentiated in the pericycle in this region. The 
shaded mass within the inner endodermis (i. e.) is a group of 
sclerotic tissue. The structure found a little higher up in the 
nodal region is seen in Fig. 42. The xylem of the leaf-trace 
has become separate, but the phloem is still attached at one 
end. The little group of endodermal cells (/.) was not well 
preserved, but appears to form a ring as shown in the diagram. 
Higher up, this ring becomes broader, until it meets and fuses 
with the outer endodermis, which bends inwards on either side 
between the leaf-trace and stele. The endodermis then splits 
so that the stele and the leaf-trace are each surrounded by an 
endodermis. In this way the continuity of the endodermal 
sheath is not broken. Fig. 43 shows the leaf-trace (/. t.) on 
its way out through the cortex. It has a slightly arched 
xylem with a protoxylem-group at the median point on 
the inner side. The phloem is nearly continuous, or perhaps 
interrupted for a short distance near the middle of the 
inner side. For the petiole see p. 421. 
The stele of A. cuneata has the same type of structure as 
A. mexicana and A.coriacea 3 and is intermediate between them 
in size. 
In A. aurita an unexpected structure was found in the 
rhizome. The stele is about -J mm. in diameter, which is 
slightly larger than in A. coriacea. The xylem forms a nearly 
solid mass of circular outline, and consists of tracheides, with 
a few rows of parenchyma-cells among them. The large 
tracheides are towards the centre, and the smaller ones at 
to refer A. coriacea , Griseb,, to A. hirsuta ; but Mr. J. G. Baker has since seen 
specimens of A. coriacea and is of opinion that it is distinct from A. hirsuta. 
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