24S 
Browne . — The Anatomy of the 
the other cones with the anatomy of which we are acquainted. No great 
radial depth of xylem is found, but the tendency is well marked and should 
be borne in mind in considering the longitudinal reconstructions of the axial 
stele, in which it is, of course, not apparent. Secondly, continuous tracts of 
xylem extending uninterruptedly above some of the traces of a whorl to 
other traces of the whorl above were a more marked characteristic of the 
cones of E. giganteum than of those of any other species yet examined by 
me. These sweeps of internodal xylem form very obvious features in the 
longitudinal reconstructions of the steles of Cones A and B, and occur also 
in that of Cone C, the xylem of which is less well developed. 
Such continuous internodal tracts of xylem seem to be uncommon in 
the cones of Equisetum ; but I have found them in all cones of E. arvense 
of which I possess serial sections of any considerable part of the cone. 
They occur, too, in the cones of E. hyemale , E . palustre, and E. maximum. 
In the two former species they are found chiefly above the annulus and in 
the upper, narrower part of the stele. In the latter position I am inclined, 
as already stated (Browne (2), p. 260), to regard their presence as resulting 
from the considerable reduction in width of the stele. Such an explanation 
does not account for their occurrence in the cones of E. arvense and 
E. giganteum. Here their presence, which involves the absence of a mesh 
over one or more median traces, is an indication of considerable development 
of xylem. Incidentally I may state that I have not observed in E . limosum 
any case in which considerable bands of xylem extended through a whole 
internode. Occasionally, however, two bundles that have fused and have 
given off two lateral traces, one from each end of the woody band, remain 
united into a wide strand in the internode above ; e. g. the strand from which 
the third and fourth traces of the fourth whorl of Cone A of E. limosum have 
departed (Browne (1), p. 676). We cannot here, however, speak of the absence 
of a parenchymatous mesh, since such meshes do not arise above lateral 
traces. Not only are these comparatively wide sweeps of internodal wood 
common in E. giganteum , but I have observed that they may involve the 
absence of a mesh over as many as three laterally consecutive, median 
traces, that is over a larger number of traces than in the other species 
studied. 
It will be remembered that in the cone of E. maximum a tendency 
resulting in increase of axial xylem was noted : strands were often linked 
up by the formation of additional xylem below the departure of traces 
(Browne ( 2 ), p. 237). This character is met with also, though more rarely, 
in the cones of E.palustre (cf. the reconstruction of the stele of Cones A of 
this species, Browne ( 1 ), p. 671), and is found fairly often in the cones of 
E. giganteum. When it is found at a level at which the internodal sweeps 
of xylem referred to above are present, there arise wide internodal bands of 
xylem separated by two or three small, free bundles, or in extreme cases 
