Anatomy of the Cone and Fertile Stem of Equisetum. 667 
lower ones). But in some cases a parenchymatous mesh only makes its 
appearance half-way or more than half-way up the internode (e. g. the 
meshes appearing above the 
fourth trace of the first whorl, 
above the fourth and eighth 
traces of the fourth whorl, and 
above the third trace of the 
fifth whorl of Cone A). In 
other cases the meshes, though 
not originating so high up in 
the internode, yet made their 
appearance at an unusual dis- 
tance above the node. In a few 
cases we pass from a trace of 
one whorl vertically upwards to 
the trace of the next whorl 
without meeting any parenchy- 
matous tissue. Thus we get a 
relatively wide continuous tract 
of woody tissue connecting part 
of one whorl with a portion of 
the succeeding whorl (e. g. the 
tract of xylem extending above 
the fifth and sixth traces of the 
* seventh whorl, that above the 
third trace of the eighth whorl, 
and that above the first and 
second traces of the tenth whorl 
of Cone A). The extent of such 
sweeps of xylem, though rela- 
tively the same, is of course 
actually much greater in a ma- 
ture cone than in so young a 
one as Cone A. Such absence 
of one or two meshes throughout 
an internode is not common in 
any one cone ; but I have found 
it in all specimens of which I 
made serial sections of any con- 
siderable portion of the cone, 
even in those that contained 
relatively little xylem. If, instead of involving one or two xylem-strands 
of the internode below, these sweeps of xylem extended above all the 
Text-FIG. i. Longitudinal reconstruction of the 
xylem of Cone A. The xylem of the stele has been 
cut in two, spread out flat. Axial xylem black ; leaf- 
traces and parenchyma white. Magnification circa 16. 
