290 MR. HENFREY ON THE ANATOMY OF THE STEM OF VICTORIA REGIA. 
roots are articulated, and when they separate leave a clean fracture ; the condition of 
the root-scar is, such as I have just described it, in all parts ; that of the leaf-scars 
exhibits the open end of air-canals of large size, which traverse the petiole longitudi- 
nally ; these are continued into the cortical part of the stem for a short distance, and 
then terminate abruptly in blind ends before reaching the central substance of the 
stem. The terminal portions of some of the vascular bundles supplying the leaves 
ramify very beautifully over these blind pouches forming the internal terminations of 
the air-canals of the petioles. 
Midway between the rows of two successive spiral series of leaves are found rows, 
also spiral, of the scars of flower-stalks (Plate XIX. fig. I c), distinguished from those of 
the leaves by the absence of the root-scars beneath them, by their round section, their 
smaller size, the different arrangement of their air-canals, and, moreover, by the fact 
that they are not supported by a firm internal process, derived from the central sub- 
stance of the stem. These are the principal points seen on the outside of the stem ; 
it may be added, that the habit of growth is just what the arrangement of its struc- 
tures would lead us to suppose ; it grows by the continuous development of a terminal 
bud alone, which, like that of a Palm, throws out leaf after leaf in a spiral course, 
each leaf being furnished with a branch-like process of the central vascular sub- 
stance, which remains as a projection, marked by the scar of the leaf and its bundle 
of roots after these have fallen off. The scars of the flower-stalks are remarkable for 
being so far distant from the axils of the leaves, which must be supposed to subtend 
them, and it appears to me that the flower-buds do not become developed until the 
leaves of the series above them, as well as of that below them, have been perfected. 
There is no tap-root to the perfect plant ; that which exists in the embryo never 
becomes developed, and its place is supplied by adventitious roots, as is regularly the 
case in Monocotyledons, to which class indeed the external characters of the stem of 
Victoria would lead us to refer it. 
When we come to the examination of the internal structure of the stem, the Mono- 
cotyledonous character becomes still more apparent. There is no bark, no pith, no 
circular arrangement of the vascular structures, and nothing analogous to a cam- 
bium layer. Even in the simple vertical section of the stem (Plate XIX. fig. 2) we see 
the scattered, isolated condition of the vascular bundles (Plate XIX. fig. 2g), the 
distinguishing mark of the Monocotyledonous stem, and when we look into the 
anatomy more closely the first impression is confirmed. 
The outer casing of the stem consists of .a thick layer of very spongy substance 
(Plate XIX. fig. 2 d ; Plate XX. figs. 3, 4 d), composed wholly of firm cellular tissue, 
forming the boundaries of intercommunicating cavities, very much resembling in form 
and arrangement the cavities in the cellular tissue occurring between muscles, &c. in 
the higher animals ; only it is stiff and resisting here, and does not collapse when the 
air is let out. Within this spongy layer is found a region of densish cellular tissue 
(Plate XIX. fig. 2 e ; Plate XX. figs. 3, 4, 5 e), of a white opake colour to the naked 
