126 РІЗТІАСЕЖ. 
double series of vascular fascicles, опе of which is external, 
the other internal, there is no central cavity. 
The air cavities continue to the base of the new azis, they 
there terminate abruptly. The vascular bundles contain no 
spiral vessels, but simply ducts. The axis is composed of a 
dense aggregation of small cellules, its whole structure is 
much more dense than that of any other part. It contains a 
considerable quantity of spiral vessels, simple and of small 
diameter, some of these continue their course along the axis, 
others branch off and supply the leaves etc. Raphides are 
very abundant, their form presents nothing peculiar. The 
roots present on a transverse section a central dense mass 
composed of cellular tissue and ducts of ordinary appearance 
immediately surrounding this, is cellular tissue, from which 
compound cells radiate towards the circumference : these com- 
pound cells are separated from each other by partitions of 
cells arranged in a single series. Between these and the cu- 
ticle, tolerably lax cellular tissue occurs, the radical fibres ori- 
ginate from the central and vascular fascicle, they cross 
. through the compound cells and then pierce the cuticle, part 
of which they carry with them in the form of the sheath. 
At their exit there is a distinct rupture of the cuticle. The 
. radical fibres appear never to lose their sheaths, their struc- 
ture is the same as that of the roots from which they origi- 
nate. 
The superior surface of the leaves is green, the inferior 
white, both are equally pubescent, the cellular substance of 
the leaf is divided into a great number of air cavities, which 
approach much nearer to the cuticle of the inferior surface 
than to that of the superior. Between these and the upper 
cuticle, are layer of small viridised cells. Towards the peti- 
ole, the only space unoccupied by air cells, is that between 
the veins; this is filled up with cellular tissue, and ge- 
nerally, one or two vascular fascicles intervene between the 
fascicle near the upper surface, and that near the under sur- 
face. If however a section be made of the more expanded 
