241 
Cone and Fertile Stem of Equisetum. 
the reduction of xylem, this reduction being manifested by the extension of 
parenchymatous meshes upwards, downwards, and laterally * (Browne ( 1 ), 
p. 699). In a later paper dealing with E. maximum it was pointed out that 
though the stele of the cone of this species consists of a very irregular net- 
work of strands, these irregularities were chiefly due to the poor develop- 
ment of axial xylem at the nodes, so that parenchymatous meshes arising 
above the traces of a whorl persisted through more than one internode, 
sometimes through numerous internodes. In Cone B of E. maximum one 
of the meshes extended into seventeen internodes. In this species the 
poor development of the axial xylem often caused the meshes of the second 
or higher orders to be widened, either suddenly or gradually, above the 
nodes by the dying out of the tracheides above a lateral or slightly internal 
trace. A tendency was further noted in this species for a parenchymatous 
mesh to become decurrent for a little distance below and to one side of the 
trace above which, speaking phylogenetically, it may be considered to have 
arisen (Browne ( 2 ), p. 235). 
A study of the reconstructions of the steles of the cones of E. hyemale 
(Text-figs. 2, 3, and 4) and E. giganteum (Text-figs. 5, 6, and 7) will show 
that here too a large number of meshes are closed at or near the level of 
a fertile node, and that fresh meshes usually make their appearance at 
a little distance vertically above traces that have departed. Usually the 
amount of xylem present at the nodes is insufficient to close all the meshes 
of the internode below (cf. PI. VIII, Fig. 8). Consequently some persist 
through each node, except through the seventh node of Cone A of 
E. giganteum. Here all the meshes are closed, though no single section 
shows a complete ring of xylem, because all the traces are not inserted at 
precisely the same level, and one of the meshes is only closed after some of 
the meshes of the internode above have made their appearance. 
Although none of my reconstructions of the cones of E. hyemale show 
closure of all the meshes at any one node (except at the extreme apex of 
Cone B), the origin of the great majority of the meshes vertically above 
traces is perhaps more marked in the well-developed stele of Cone A of 
this species than in the steles of any other cones studied by me, except 
those of E. arvense. Moreover, Cone A shows an unusually high proportion 
of meshes of the first order. Cones B and C of this species have a less 
developed vascular system. 
Forty-eight meshes arise and are closed within Cone A of E. hyemale . 
Two more unclosed meshes arise above traces of the eighth whorl and 
become confluent round the vascular strand of the terminal acumen. Of 
the forty-eight meshes I regard twenty-seven as of the first, sixteen as of 
the second, three, as of the third, and two as of the fourth orders. Nine 
more meshes arise above the annulus ; two of these are closed at or near the 
insertion of the lowest whorl of sporangiophores, and may be regarded as of 
