234 Browne.—A Second Contribution to our Knowledge of the 
the second order, persist into the cone itself, i. e. into the internode above 
the lowest sporangiophores. 
Meshes originating above the Annulus. 
(The space between the annulus and the lowest fertile whorl is considered as an internode.) 
Orders .* *12345678 Total. 
Cone A13210000 7 
Cone B o 1 3 1 2 1 1 1 10 
Meshes originating above the Last Leafy Whorl. 
(The spaces between the last leaf-whorl and the annulus, and between the latter and the lowest 
fertile whorl, are considered as internodes.) 
Orders: 1 2 3 4 5 6 7 8 9 10 ir 17 Total. 
Cone A65425010100024 
• Cone Bio 9 7 5 3 2 1 1 o 1 11 41 
General Characters of the Xylem of the Cone. 
The individual tracheides of the cone of E. maximum resemble in 
structure those of the other cones of Equisetum studied by me, viz. 
E. arvense , E. palustre , and E . limosum ; that is to say, they are provided 
with spiral or annular thickenings. In the species at present under con¬ 
sideration they are markedly less strongly lignified, and their walls are 
frequently only slightly thickened. In mature cones their average diameter 
is slightly less than in the three species already studied. Moreover, there 
are more parenchymatous cells mingled with them than with the tracheides 
of the other species. In comparing the reconstructions of the xylem of the 
cones of E. maximum with the reconstructions of the xylem of such 
a species as E. arvense , we should bear in mind that in the latter species 
the xylem constitutes a more or less solid cylinder, though one of little 
radial depth, while in the former the xylem forms a cylinder consisting 
chiefly of woody cells, but also of numerous patches of unlignified 
parenchyma. These patches are too small to be shown in the recon¬ 
structions of the xylem ; they are commonest at the extreme base of large 
cones such as Cones 13 and D (see PI. XIV, Fig. 3). In places, it is true, 
and oftenest near the point of departure of a trace, the xylem of a bundle 
forms a more or less continuous band (see PI. XIV, Fig. 1). Detached 
groups of tracheides, usually of small calibre, occur more internally in the 
bundle, as they do in all the species studied, but rather more frequently 
than in these. Such groups of small tracheides tend to become torn and 
disorganized very early, before the formation of definite carinal canals. 
The traces of the sporangiophores of Equisetum maximum are rather 
smaller than those of the other species studied, and in the longitudinal 
reconstructions of the xylem of the cones it has, in many cases, been 
necessary slightly to exaggerate their size, in order that they should be 
clearly distinguishable. 
