Bower.—Studies in the Phytogeny of the Filicales. 
DESCRIPTION OF PLATES XXXII AND XXXIII. 
Illustrating Professor Bower’s Paper on Plagiogyria. 
Fig. i. Plagiogyria pycnophylla. Parts of two pinnae seen from below, with a pneumatophore 
at the base of each ; on one side of the right-hand pinna the indusial margin and the sporangia have 
been removed, so as to show the venation and the absence of distal connexions of the veins. ( x 4.) 
Fig. 2. Plagiogyria semicordata. Parts of two pinnae seen from below, from near to the apex 
of the leaf; on the right-hand side the indusial margin and the sporangia have been removed, so as 
to show the venation ; note the winged character of the rachis, which is specially developed at the 
apical region of the leaf, (x 4.) 
Fig. 3. Apical bud of Plagiogyria glauca, showing leaves still circinate and bearing the 
pneumatophores projecting from the enlarged leaf-bases. ( x 2.) 
Fig. 4. P. glauca. The persistent base of an old leaf, showing a row of pneumatophores on 
either side of the midrib. (Enlarged.) 
Fig. 5. Circinate apex of leaf of P. pycnophylla , showing the pneumatophores projecting through 
the covering of mucilaginous hairs. ( x 2.) 
Fig. 6. Transverse section through a well-developed stock of P. pycnophylla, showing the 
central sclerotic core (sc), the stele (si), the leaf-traces (//), and their subtending sclerotic patches 
(sp), which as they pass outwards become hollowed by surface involutions (inv). To the left is 
a solenostelic stolon in place of a normal leaf (sol). ( x 2.) 
P'ig. 7. Transverse section of the stem of a well-grown plant of P. pycnophylla at a point close 
below the apex, to show the position of the protoxylem-groups, which are indicated as dark dots 
in the meristeles; note that the first indication of the formation of a leaf-trace is by an outgrowth 
of the central sclerotic core, and that a mesoxylic protoxylem-group appears opposite it in the 
meristele of the axis. ( x 6.) 
Fig. 8. Part of a meristele of P. glauca, showing the first protoxylem-elements already lignified, 
lying in a distinctly mesoxylic position. ( x 100.) 
Fig. 9. Part of a meristele of P. pycnophylla, showing mesoxylic protoxylem. ( x 250.) 
Fig. 10. A leaf of P. pycnophylla, itself arrested in its growth, and bearing on its adaxial face 
a stolon (si) ; pn indicates the pneumatophores. 
Fig. 11. A succession of transverse sections through a leaf bearing a stolon, the lowest being 
placed first; see text. ( x 4.) 
Fig. 12. I-V. Successive sections through a stolon of P. pycnophylla y showing a structure not 
far removed from solenostely; on the right-hand side of the drawings a stolon, which replaces 
a leaf, is originating, and in IV it shows a stolon structure (si). (Natural size.) 
Fig. 13. Tangential section through the leaf-bases of P. pycnophylla, showing how one of 
them is structurally replaced by a stolon (si) having a stele which is almost protostelic. (Natural size.) 
Fig. 14. Transverse section through a young pinna of P. pyc 7 iophylla, showing marginal 
segmentation of the usual Leptosporangiate type. ( X 300.) 
Fig. 15 (bis). Sections through the sorus of P. pycnophylla, in an advanced state, but not 
mature; a and b show the ‘ mixed ’ character of the sorus, which is covered by the attenuated margin 
of the pinna, these sections being transverse through the pinna, and following the course of the 
veins ; c is at right angles to these, and cuts the vein transversely. ( x 30.) 
Fig. 16, a-h. Sections through sporangia of P.pycnophylla in early stages of development; for 
details see text. ( x 225.) 
Fig. 17. Older stages of the same; a, b, transverse sections through the sporangial stalk ; c and 
d, sections longitudinally and transversely through the sporangial head, (x 225.) 
Fig. 18, a-e. Mature sporangia of P. semicordata ; for details see text. ( x 80.) 
