— 218 — 
lanceolate and directed obliquely or vertically upwards. Its 
structure is isolateral (fig. 49). The epidermis is thick and 
most of its cells on both surfaces have a thick mucilaginous 
inner wall which in transverse section presents a characteristic 
appearance, two light stripes showing between the green tissue 
and the cell cavities of the epidermis. These cavities are 
filled with tannic acid and the contents are therefore dark. 
Fig. 49. Stellera Lessertii. A, Leaf in transverse section. 
Ba iid 203: 
There are stomata on both surfaces. The palisade cells occur 
in 2 or 3 layers above and below; the centre is occupied by 
the veins which take up most of the space; between them 
there are 2 or 3 layers of rounded cells less rich in chloro- 
phyll, and many “Speichertracheiden” (shaded in fig. 49). 
A young stem shows a thick but non-mucilaginous epid- 
ermis with stomata which are not sunk; below this are 3 
layers of rounded green-cells of which the outer ones are 
slightly palisade-like. These are followed by about two layers 
of round or tangentially extended cells containing a small 
