Hick ling.* — The Anatomy of Palaeostachya vera. 373 
phore. It has here divided to form four or five layers of periderm cells 
(Fig. 10 ,pd.). The epidermal layer itself Is perfectly normal. 
The most interesting feature of the cortex is its elaborate system of 
sclerized elements. Briefly, the stereome structure consists of a series 
of thick rings, one at each node, placed like phlanges round the cylinder 
of xylem strands and sclerized medulla, and braced together externally 
by vertical sub-epidermal sclerized strands. Such a skeleton must have 
made the axis extremely rigid, and no doubt points to an erect habit for 
the cone. The nodal rings (the g discs’ of Williamson) are simply zones 
of sclerized parenchyma occupying the entire width of the cortex, and 
having a vertical thickness about equal to their width (Figs. 1, 3, and 7). 
The junction of the sclerized zone 
with the soft cortex was not 
sharply defined, the extent of the 
sclerization here, as in other parts 
of the cone, being variable. Since 
a complete sclerized ring would 
be a physiological impossibility, 
large rounded intervals were left, 
through which the soft tissue was 
continuous (Figs. 1 and 7, Text- 
Fig. 1). By the decay of the 
soft tissue they now appear as 
‘canals* (the ‘cortical lacunae’ of 
Williamson), but in one case 
(Fig. 8, par) there is sufficient soft 
tissue left to justify the view here 
stated. These * canals 5 alternate 
in position with the pairs of 
bundles, and are usually nine, occasionally eight or ten in number. The 
‘ disc ’ provided a firm basis for the attachment of both bracts and 
sporangiophores, the mechanical tissue of each of which joined on to it. 
From the edge of the disc, between the bases of the sporangiophores, 
vertical bands of sub-epidermal sclerization swept upwards. Sometimes 
the whole band from node to node was sclerized, sometimes the upper 
portion appears to have remained soft, so that the sclerized part remains 
as a long, upward-projecting tooth. In some cases these bands joined 
up laterally just above the disc to form a complete sheath of sclerized 
hypoderma. It is evident that here, as in the disc itself, the extent of the 
sclerization is somewhat variable. These variations are Indicated in Text- 
Brig. 1, and in the accompanying Text-Fig. 3. 
Medulla. Within the ring of vascular bundles there was a zone of 
medullary tissue around the pith-cavity some five to ten cells in thickness. 
Fig. 3. Oblique- transverse section. Q. 334. 
X about 1 1 . Showing irregularity of sub-epidermal 
strands of cortical sclerenchyma. The plane of the 
section rises from A to B. 
