694 Browne . — Contributions to our Knowledge of the 
and seems to be one result of a lesser development of xylem. The latter 
being insufficient to bring the strands laterally into contact at the node, their 
connexion is effected higher up by the oblique course of the tracheides present. 
Strong confirmation of the view that the annulus marks the position of 
a reduced node was afforded by the region transitional from the fertile stem 
to the cone in Cone F of E. arvense. This specimen had two annuli ; the 
upper one was normal in appearance, the lower one was rather more 
developed than is usual in this species, especially on one side where the 
edge was slightly lobed. The insertion of this lower annulus on the axis 
was remarkably oblique, a phenomenon which may occasionally be observed 
in normal annuli. According to Duval Jouve the possession of more than 
one annulus and irregularities of the annulus are very common in E. arvense , 
E. maximum , E. littorale , and common in E. sylvaticum , E. limosum , and 
E. ramosissimum (Duval Jouve, pp. 150 and 154). Milde goes so far as 
to describe the cone of Equisetum as having one to two annuli (Milde, 
p. 1 61). But I know of no account of the anatomical relations of such 
abnormal forms. A little distance below the lower annulus of Cone F the 
anatomy of the stem was that of a typical internode of the vegetative region. 
There were seven more or less equivalent bundles, each with a large carinal 
canal and two small lateral groups of metaxylem. A little higher up 
reticulate tracheides, resembling those of a vegetative node, make their 
appearance in the adjacent halves of two bundles ; these two groups of 
tracheides and the phloem external to them pursue a course so oblique 
that about 30 to 40 /x higher up they come into contact. The reticulate 
wood thus formed is of the same radial extent as that of an ordinary 
vegetative node ; but in the direction of the circumference of the stele it at 
first occupies only the portion of the stele lying between the carinal canals 
of two adjacent bundles. The lateral groups of metaxylem at the free ends 
of these bundles persist for a little distance in the condition of typical 
internodal lateral metaxylem ; but a little higher up they and the cells 
beyond them become connected with and assume the character of nodal 
wood. There results a band of reticulate tracheides extending over rather 
more than a quarter of the circumference of the stele. This band of xylem, 
however, very soon breaks up into three bundles by the dying out of portions 
of the woody band. About 320 above the first appearance of the reticulate 
tracheides the band of xylem has broken up into three normal sized bundles; 
the middle one is already in a typical internodal condition, each of the 
others consists of a curved band of typical ‘ nodal xylem ’. Traced upwards 
these reticulate tracheides, the free ends of the band of reticulate wood, do 
not die out, but pursue an obliquely transverse course, passing in opposite 
directions round the circumference of the stele (Fig. 5 ) PI. LXIV). Thus a 
mass of tracheides appears at different levels in all the bundles. When the 
two strands of reticulate tracheides and the phloem outside them have 
