the Anatomy of the Cone and Fertile Stem of Equisetum. 439 
ones of the second whorl of Cone e). Prematurely divided traces also 
occur (e. g. those of the first sporangiophore of the third whorl of Cone B, 
and of the second sporangiophore of the lowest whorl of Cone D). The 
traces of the third, fourth, and fifth sporangiophores of the third whorl 
and of the fifth sporangiophore of the fourth whorl of Cone A originate 
as deeply lobed bundles which fork almost at once. 
The sporangiophores of E. variegatum , though small, have relatively 
long, slender stalks. Only two examples of concrescence of sporangio- 
phores were observed outside the apical region ; the seventh and eighth 
traces of the fourth whorl of Cone A, and the fifth and sixth traces of 
Cone B entered pairs of nearly completely concrescent sporangiophores. 
The third trace of the latter whorl supplied an unusually large sporangio- 
phore, apparently single in nature, though intermediate in size between 
the double sporangiophore and the other sporangiophores of this whorl. 
VI. The Region transitional from Stem to Cone. 
In E. sylvaticum parenchymatous cells are less freely distributed in 
the axial metaxylem in the region of insertion of the annulus (PI. XXI, 
Fig. 1). Here the metaxylem is also usually of greater radial extent, 
and consists in part of rather wider tracheides. In Cone B, particularly, 
some of the tracheides in this region strikingly recall in size and form 
those of the nodal (or supranodal) wood, certain of them even possess- 
ing reticulate thickenings. No reticulately thickened tracheides were 
found at the corresponding level of Cones A and D, and the sections of 
Cone C did not include this region. The protoxylem is somewhat dis- 
organized at this level, although definite carinal canals have disappeared 
or are disappearing. Higher up, canals, smaller and less definite than 
those of the internode below the annulus, make their appearance. In 
Cone A the region between the insertion of the annulus and the basal 
whorl of the cone has elongated very little, and the amount of axial xylem 
at the level of the departure of the traces of the lowest sporangiophores re- 
mains greater than is general in the cone, though the tracheides are less 
numerous, and more parenchymatous cells are interspersed among them 
than immediately below, where the supra-annular anastomoses occur. In 
Cones B and C, where the region between the annulus and the sporangio- 
phores has elongated considerably, there is, when we reach the insertion 
of the sporangiophores, no unusually large amount of axial metaxylem. 
In the reconstruction of the stele of Cone B a small white cross maybe 
seen near the lower end of the sixth strand. At this point two tracheides 
protrude from the stele, as though they formed part of a trace. They 
are accompanied by two or three phloem-like and endodermal cells, oriented 
in the same way, i. e. with their long axis directed at right angles to those 
of the corresponding cells of the bundle. The cells of this incipient trace 
