255 
Cone and Fertile Stem of Equisetum. 
given off from the axial bundles by a horizontal line across them, while in 
those of Cones B and C they are shown as crosses. The annular traces 
proper, i. e. the strands that are in connexion with the axial bundles, at 
first pursue a steeply upward course. In a transverse section of the stem at 
the point at which the annular traces become free, the tracheides of the 
latter are cut almost transversely, and offer a striking contrast to those of 
the traces departing to sporangiophores ; for the traces of the latter pass 
out approximately horizontally and their traces are, therefore, cut more or 
less longitudinally in a transverse section of the axis. Soon, however, the 
annular trace bends sharply out into the parenchymatous tissue of the 
annulus ; in the region of the bend there is usually a slight downward 
bowing of the annular traces, but they soon run outward and upwards. The 
traces are, usually at least, somewhat smaller than those of the sporangio- 
phores of the whorl above them. Some of them fork near the free edge of 
the annulus, and the branches or unbranched bundles run to the point of 
insertion of the sporangia. The sporangia borne by the annulus are fitted 
in very closely with those of the downwardly directed sides of the lowest 
sporangiophores, and transverse sections of the axis in this region frequently 
pass through sporangia borne by the sporangiophores as well as those 
borne on the annulus. 
The number, distribution, and behaviour of the annular bundles vary 
considerably in the different cones. The vascularization is most pronounced 
in Cone C, where the number of annular bundles is eleven, only one less than 
the number of the traces and sporangiophores in the lowest whorl of the 
cone. Four of these bundles are in connexion with the axial strands, and 
are hardly smaller than the traces of the sporangiophores immediately 
above. Each of these four annular traces forks once, and one of the 
branches forks again. Each of the nine strands thus formed runs to the 
insertion of a sporangium. The remaining seven strands are free annular 
bundles. There is no sharp line of differentiation between the tissues of the 
axis and those of the annulus. As the latter is adherent by its wide base 
to the stem, the stele, just below the level at which the annulus detaches 
itself, is surrounded by a wide parenchymatous cylinder in which 
the free annular bundles end blindly at very different depths. Four of 
them are unbranched and terminate at the insertion of a sporangium ; the 
three others fork near the edge of the annulus and each branch runs to the 
point of insertion of a sporangium. In this cone the annulus bore nineteen 
sporangia. 
The annulus of Cone A contains six vascular bundles, none of which 
enter into complete connexion with the axial bundles. The third, as seen 
in the reconstruction of the stele (Text-fig. 5), approaches very near to the 
central cylinder, and one or two phloem-elements appear to pass out from 
the axial bundle, but no connexion is established between the tracheides of 
s 
