Internodal Vascular Strands of Equisetum. 17 
persistent through the lower internodes of the cone. The bundles 
in the internode of the cone of E. palustre are very much like 
those of the cone of E. arvense ; but though varying somewhat they 
are on average markedly narrower and their xylem tends to attain 
a very slightly greater depth radially. In the internodal bundles of 
the cones of E. limosum and E. hiemale the xylem is of no greater 
radial extent than in the similarly situated bundles of E. arvense » 
and the bundles themselves are, typically, quite as narrow as those 
of E. palustre. Those of E. gigdnteum have a considerably greater 
Text-Fig. 6. (a) Transverse section of vascular bundles of E. giganteum* 
just below insertion of annulus, x circa 250. (b) Transverse section of 
vascular bundle of E. giganteum from axis just below the insertion of the 
annulus x circa 200. (c) Transverse section of small bundle of E. arvense , 
between the insertion of the annulus and the lowest whorl of sporangiophores, 
X 200. 
radial depth of xylem, as may be seen in Text-Fig. 4 b, representing 
a small bundle of the internode of the cone of this species. In the 
fully developed bundle of this species the xylem is usually five to 
six, not uncommonly seven to eight cells in depth, so that the wood 
forms oval masses, sometimes broken up by or enclosing parenchy¬ 
matous cells. 
