It takes place in the internodal cells of Characeae; in the old internodal cells of ~- ~ ~ - -.
If L 1 is the internodal distance and U 1 the velocity in a gas, L and U being the corresponding values for air, we have U 1 /U =L1/L.
The internodal parts will'not often divide so as to form separate individual plants; sometimes, however, this happens; it is said that the smallest piece of Torenia asiatica, for instance, will grow.
On germination it gives rise to a row of cells in which short (nodal) and long (internodal) cells alternate.
A, Longitudinal section of the rhizome, including a node and portions of the adjoining internodes; k, septum between the two internodal cavities, hh; gg, vascular bundles; 1, vallecular canal; s, leaf-sheath.