Jeffrey and Torrey . — Transitional Herbaceous Dicotyledons. 231 
parenchyma of the leaf-gap. Such gaps are found more or less well 
developed in the secondary wood of all of the Pteropsida. On the outer 
(also the lower) side of the foliar trace there is no corresponding thick radial 
mass (see Fig. 2, PL XI) of storage parenchyma, except in forms provided 
with foliar rays (see Fig. 6, PI. XI). Notable in this connexion, of course, are 
the Dicotyledonous herbs at present under discussion. 
We may now consider with advantage another group in which herba- 
ceous types occur side by side with arboreal. The Urticales will excellently 
serve in this connexion, because they are regarded by many, by reason of 
the chalazogamy which they manifest, as among the lowest of the Dico- 
tyledons. Beginning as before with an arboreal representative, Fig. 13, 
PI. XII, shows a complete view of a year-old stem of the American Elm, in 
the region of the node. The position of the traces is revealed by three 
marked depressions on the inner border of the pith. Fig. 14, PI. XII, shows 
one of the leaf-segments of the woody cylinder, more highly magnified. It 
is clear that outside the leaf-trace the wood is practically normal in 
structure, showing the presence of wood rays, fibres, and vessels. 
In Fig. 1 5, PL XII, is shown a total view of the nodal region of the thicker 
part of the stem of Boehmeria nivea , the so-called ‘ Fibre-Ramie This 
Urticaceous herb presents a marked contrast to the Elm in the nodal 
region, by reason of the presence of distinct and broad parenchymatous 
bands corresponding to the position of the leaf-traces in the stem. These 
are the foliar rays and are just as characteristically developed in the herba- 
ceous representatives of the Urticales as they have been shown above to be 
in the Malvales. Fig. 16, PL XII, shows a detailed view of one of the leaf- 
segments of the stem and its corresponding foliar ray. The small leaf-trace 
is here again externally subtended by a well-developed parenchymatous leaf- 
ray in marked contrast to the generally woody organization of the central 
cylinder. The facts here, too, are as irreconcilable with the statements of 
our critics as they have been shown above to be for the Malvales. Fig. 17, 
PL XII, shows a higher region in the stem under a somewhat less magnifica- 
tion than that employed in the case of Fig. 16. In this illustration the foliar 
trace is still in the cortex and has not made its way into the central 
cylinder. A gap subtends the trace in the substance of the wood, which is 
of course the foliar gap. Fig. 18, PL XII, shows a tangential view of the leaf- 
ray in Boehmeria. It is quite obvious that the foliar trace is surrounded by 
a broad band of parenchymatous tissue, particularly well marked, below the 
trace. It is thus clear that the leaf-ray shows equally well in the tangential 
and in the transverse planes of section. In Fig. 19, PL XII, is shown a much 
more magnified view of the foliar ray in the species under discussion. 
With the increased magnification it becomes clear that the leaf-ray still 
reveals vestiges of its ligneous origin by the presence of fibres more or less 
distinctly developed. Examples from herbaceous representatives of the 
