Roots of Terminalia Arjuna. 151 
which often contain stellate groups of crystals of calcium oxalate, 
and (iii.) occasional fibres, either singly or in groups. The pericycle 
is not lignified, and the endodermis is a well-marked layer, with both 
radial and inner walls somewhat thickened; occasional passage cells 
occur. 
The cortical tissue is very loose with large lacunae (Fig. 3). 
The individual cells are cylindric and arranged in irregularly radial 
rows. Beneath the epidermal layer is a hypoderm of elongated 
cells, polygonal in cross section, whose walls are slightly thickened. 
Te ridenn. 
Endoder/niS 
,-Cortex 
Fig. 3. Transverse section of cortical part of root. 
Very soon after the beginning of secondary thickening a 
periderm is formed in the outer layer of the pericycle; the primary 
cortex is afterwards cut off. An aerating tissue forming a 
“ secondary cortex” is then formed internal to the periderm. This 
is mainly derived from the secondary phloem 1 (Fig. 4). The cells 
of the phloem parenchyma split apart from one another, but also 
conjugating parenchyma is formed. In addition, some cells forming 
1 Cf. Schenk, H. Flora, 1S89. 
