I 2 I 
certain Species of the Genus Christisonia. 
layer in each organ behave just as the same cells do when in 
contact with a Bamboo-root, viz. they become much elongated 
radially, acquire purple contents, and brown, swollen walls, 
while a ferment is secreted which destroys the limiting cuticu- 
larized wall of each root in places here and there, so that 
at these points direct fusion between the elements of the two 
distinct organs takes place. Some of the cells in the neigh- 
bourhood of the fusion grow .out as papillae which bend round 
towards the point of attachment In a section through the 
point of fusion of two roots, the incompleteness of the union 
is often seen by the small, often minute, portions of the cell- 
wall, which formed the boundary between the two roots, still 
remaining, and between which vascular tissue passes from 
cylinder to cylinder ; but in other cases the fusion is complete. 
The roots attach themselves to each other in all directions 
and at every angle, so that an intricate network is formed, as 
seen in Fig. 2 . In this way, those parts of the root-system 
distant from a tuber are more readily supplied with the 
nutriment which they need for their work of extension and 
the building-up of the flowering-stems. 
At places here and there on the roots, as well as on the 
tubers, young stems arise. These are of endogenous origin, 
being derived from the central cylinder of the root, and 
probably from the pericyclic layer (Fig. 20). 
Their origin becomes obscure as they increase in age, so 
that, like the lateral roots, they appear to be of cortical origin; 
the external layer of the root remains intact around the apex 
of the young stem for some time, becoming very much bent 
and stretched outward ; it finally snaps and gets left behind 
as a flap of a single layer of cells on either side of the young 
growing stem. Unlike the lateral root, the young stem has 
no dissolving action on the cells of its parent-root, but simply 
pushes its way outward through the cortex ; its outward 
course will, therefore, probably be less rapid than that of the 
former organ. The young stems are in the form of small, 
conical elevations on the root, which, in their youngest stages, 
appear as mere dimples on the surface ; a median section 
