954 
Fi 
PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
irregular canals, in which remains of the protoxylem (px) can be traced. 
All the tissue within the ring of bundles is pith. A few tangential inter- 
fascicular cell-divisions have taken place. C.N.991. x 70. 
. 24, From a transverse section of another strobilus, showing the stele and part 
of the cortex. Here there are probably 6 bundles, in groups of 2 (as at pa, 
where their protoxylem is shown). Secondary thickening has made considerable 
progress. In other respects the structure is similar to that in the last figure. 
C.N. 1016. 76. 
Fig. 25. From a transverse section of a strobilus, showing the quadrangular stele 
and part of the cortex. There are 4 vascular bundles, one at each corner. 
Tangential divisions have begun in the cells of the interfascicular tissue. 
px, the 4 groups of protoxylem. C.N. 10134. xX 70. Compare Plate 74, 
photograph 14. 
Fig. 26. Part of a somewhat oblique transverse section, showing a vascular bundle in 
connection with the cortical tissues. p,p, pith; a,2, xylem; pz, proto- 
xylem; ph, phloém-group ; pe, pe, probable pericycle ; v,c, cortex. C.N. 1013. 
x 200. 
PLATE 81. 
Calamostachys Binneyana. 
Fig. 27. Part of an approximately median longitudinal section of the axis of a large 
Fig 
strobilus. y,p, the wide pith of the cylinder ; on either side is the xylem of 
a vascular bundle. Two canals are shown with remains of the protoxylem 
(px), (px). c,c, the cortex, of which only the inner layers are shown. The 
section passes through a whorl of sporangiophores. C©.N. 10224. x 70. 
. 28. Tangential section through a vascular bundle of the same strobilus. The 
section passes through a node bearing a whorl of bracts (the second sterile 
node from below, shown in photograph 10, on Plate 73). The canal of the 
bundle, with the protoxylem (px), is shown both above and below the node. 
The nodal wood has short: reticulated tracheides. In the internode the 
trachee are generally scalariform. The parenchyma on either side belongs 
to the stele. C.N. 1022. x 70. 
Figs. 27 and 28 are from the same preparations as photographs 10 and 11, on 
Plate 73. Fig. 27 is from a part not shown in the photographs. 
Fig. 29. Peltate sporangiophore, with a sporangium attached, from an approximately 
transverse section of a strobilus. The vascular bundle is shown in the axis of 
the sporangiophore, and a branch-bundle is seen passing through the peltate 
expansion, to the base of the sporangium. The sporangium is attached to the 
edge of the peltate scale, at a. Within the sporangium are numerous spore- 
tetrads, enclosed in their mother-cell membranes. ©O.N. 996. x 70. 
