Cone and Fertile Stem of Equisetum. 251 
parenchymatous meshes cannot very well arise, and the prevalence of these 
bands, dual in origin and retaining their dual character, is no doubt one of 
the reasons why the cone of this species has so few parenchymatous meshes 
in spite of a relatively considerable amount of axial xylem. In the inter- 
node above these pairs of strands usually remain fused and form a complex 
or double strand which, though narrowing slightly, remains markedly wider 
than the single strands of the internode. At the next node these double 
strands may once more widen and again give off two lateral — or nearly 
lateral — traces more or less superposed — sometimes accurately so — to those 
of the whorl below (e. g. the sixth strand between the first and second 
whorls of Cone A of E. giganteum). More often, however, a djouble strand 
unites at the next node with another double or a single strand or strands, 
and the resulting complex or band of xylem gives rise to a group of traces 
corresponding in number to its constituent parts and alternating irregularly 
with those of the whorl below (e. g., the fifth, sixth, seventh, and first strands 
of the internode between the third and fourth whorls of Cone B of 
E. giganteum). 
As in the other cones studied by me, so in those of the two species 
now described, the parenchymatous meshes arise in by far the greater 
number of cases, vertically above traces that have departed. I have not 
observed in E . hyemale any examples of the tendency, so characteristic of 
the cone of E. maximum for parenchymatous meshes to become decurrent 
below and to one side of the traces that may be held, speaking phylo- 
genetically, to subtend them. Such behaviour of the meshes is rare in 
E. giganteum , but an example may be observed in the mesh above the 
eighth trace of the fifth whorl of Cone A. 
On the other hand, in E. giganteum more often than in the other species 
studied by me, meshes do arise not superposed to traces. In other words, 
strands branch and the point of branching does not lie vertically above 
a trace ; moreover, this branching is not necessarily associated with an 
increase in the number of traces in the whorl above. Still v even in 
E. giganteum this origin of a parenchymatous mesh between rather than 
vertically above traces is rare ; and this though the prevalence in this 
species of ‘ double strands’ giving off two lateral traces would seem to invite 
branching of the strand above and between the traces. In the great 
majority of cases these bands of xylem, dual in nature, that have given off 
two lateral or slightly internal traces, persist undivided through the inter- 
node above. 
V. Apex of the Cone. 
Both in E. hyemale and in E. giganteum the cone normally ends in 
a pointed apical prolongation, Duval- Jouve’s acumen. In E. hyemale this 
is traversed by a vascular strand which is much stouter than an ordinary 
