MR. HENFREY ON THE ANATOMY OF THE STEM OF VICTORIA REGIA. 293 
walls, which pass by gradations into the general parenchyma of the stem. The vas- 
cular bundles of the centre of the stem (Plate XX. fig. 13) are composed of very many 
such spiral vessels, or rather from their intercommunication and large size, ducts, 
collected into a cylindrical bundle. The vascular bundles of the petioles (Plate XX. 
fig. 8) present. the ducts more scattered in the cross section, since the chief bundles 
ramify as they pass out ; the vascular cord of the root-bundle (Plate XX. fig. 8 h) 
differs from that of the Monocotyledons, which has a central woody cylinder sur- 
rounded by ducts ; for the firm oblong, parenchymatous cells of this cord have the 
ducts scattered pretty regularly through its substance, Plate XX. figs. 11, 12. 
From the researches of M. Trecul, already referred to, it appears that the structure 
of the vascular bundles is similar in that plant, as is also the Monocotyledonous cha- 
racter of their arrangement. 
In conclusion, it may be stated that so far as the general arrangement of the 
structure of the stem is concerned, Victoria, like NupJiar, would appear to afford 
evidence in favour of that view which regards the Nymphseacese as Monocotyledons. 
The main difference, in fact the only one, from the rhizomes of plants of that class, 
so far as I have examined them, lies in what I believe to be unimportant points, 
namely, the absence of the fibrous layer between the cortical and central substances, 
and the composition of the vascular bundles exclusively of ducts of the unreliable 
spiral fibres. 
Explanation of the Plates. 
PLATE XIX. 
Fig. 1. View (natural size) of the side of a rhizome of Victoria regia, showing the 
spiral arrangement of the leaves, root-bundles and flowers, a, scar of leaf ; 
h, scar of a root-bundle, each facet corresponding to a root; c, scar of a 
flower-stalk. 
Fig. 2. Vertical section of the same stem, showing the central vascular region (y) 
surrounded by the cortical substance (e), which supports the spongy sub- 
stance {d) by plates {f, f) of its tissue running out horizontally ; a, b, pro- 
cess giving origin to a leaf and root-bundle; the vascular bundles of the 
leaf (a) are above those of the roots {h). 
PLATE XX. 
Fig. 3. Cross section of the stem (natural size), exhibiting the various regions ; 
references as before ; h, the vascular cord going to a root. 
Fig. 4. Another cross section, a, vascular bundles going to a leaf ; h, do. going to 
a root. 
