i53 
Roots of Terminalia Arjuna. 
large intercellular spaces. As the root increases in size the cortical 
cells grow irregularly, the result being that the cells separate from 
one another, but in places remain attached by lateral processes. A 
large lacunar system is thus formed. The connecting processes are 
at first produced mainly on the radial walls of the cells and to a less 
extent on the tangential walls, so that the cells come to be arranged 
in radial chains (Fig. 5). In time the processes are cut off by 
transverse walls. This method of growth of a lacunar system has 
been termed by Karsten 1 “ conjugating parenchyma.” 1 The process 
is helped by the rows of cells simply splitting away from one 
another. 
A point in which the roots differ from typical pneumatophores 2 
Fig. 5. Longitudinal section of cortex of a young root, showing beginning 
of “ conjugating parenchyma.” 
is that the root-tip is covered by a definite root-cap, though this 
cap is not of the normal structure seen in terrestrial roots. 3 It 
extends much further back than usual; the cap-cells continue 
as a limiting layer two to three cells deep over the region normally 
occupied by the root-hairs and do not finally disappear till a 
considerable distance behind the apex, at a point where the tissues 
1 Solereder, Syst. Anat. Dikot, 1908. 
2 Westermaier. Zur. Kenntniss der Pneumatophoren, 1900. 
3 Janczewski. Ann. Sci. Nat., 1874. 
