Boodle— Anatomy of the Gleicheniaceae. 723 
reached, when it opens, and allows continuity first between 
the inner and outer phloem (Fig. 9), and then between inner 
and outer pericycle (as in Fig. 8). Near the top of the petiole 
the reverse changes are gone through, so that the xylem 
becomes closed again just before the separation of the pinnae. 
G. dichotoma has been described at length, because its petiole 
being of an exceptional type, the nodal structures differ in 
several points from PoiraulPs description of the node of 
Mertensia, and because the completely enclosed sclerotic 
tissue with its endodermis is an interesting feature. 
The node of G. flabellata may probably be taken as fairly 
typical for Mertensia , and agrees in most points with the dia- 
grams given by Poirault (’ 93 , Fig. 16, p. 177) for that subgenus. 
The structure is as follows : — A nodal island appears in the 
stele, a few sieve-tubes appear near the middle of the island 
(i. ph. in Fig. 2) ; the sieve-tubes increase in number, and shift 
their position, so as to lie near the periphery of the island, 
forming an arc on the inner side and a scattered series on the 
outer ; in the mass of parenchyma within this ring of sieve- 
tubes a sclerotic group, surrounded by an endodermis, appears ; 
the arched xylem of the leaf-trace separates from the xylem 
of the stele at one end first, and, through the gap formed, the 
external phloem becomes continuous with the internal in the 
manner seen in G. dicarpa (Fig. 21, to be described later) ; 
then a stage, resembling that shown for G. dicarpa in Fig. 22, 
is reached, though in G. flabellata the bending in of the external 
endodermis round the sclerotic group takes place when the 
xylem and phloem of the other end of the petiolar bundle 
have become separated from the corresponding tissues of the 
stele. This point is connected with the bundle not swinging 
round so far as it does in G. dicarpa before becoming free. 
The type of structure now attained, viz. an arched bundle 
with an intrusion of endodermis and cortical sclerenchyma in 
its concavity, is continued in the petiole. 
For Eugleichenia Poirault gives diagrams (Figs. 13 and 14) 
of the nodes of G. Boryi and G. dicarpa (under syn. G. hecisto- 
phylla). In G. Boryi one may summarize his description 
3 B 
