198 Gibson . — Contributions towards a Knowledge 
peculiar condition of the middle lamella in the thick-walled 
cortex of 5. Lyallii\\%s already been described (p. 190). Chloro- 
phyll and starch are most abundant, as a rule, in the inner 
layers of the cortex, and these vary in amount from only a few 
grains to a very large quantity, as in *9. viticulosa . As already 
explained, the so-called ‘articulations’ of the Articidatae are 
due entirely to hypertrophy of the middle layers of the cortex. 
The trabecular tissue, under which may be included both 
the endodermal cells and the parenchymatous tissue associated 
with and connecting these to the more compact cortex, varies 
very considerably in character. The two commonest con- 
ditions found are, (a) an endodermal cell articulating with two 
swollen chlorophyll-bearing cells, which in turn are attached 
to the cells of the inner cortex ; and (b) a similar condition, only 
the distal parenchymatous cells undergo division and form 
a cluster of cells surrounding the distal end of the endodermal 
cell. The endodermal cell is most commonly a longer or shorter 
tubular cell, containing protoplasm and a nucleus but no 
chlorophyll, arising from the pericycle, and possessing, usually, 
a well-marked cuticular ring medianly placed. In older con- 
ditions the cuticularization may spread over the entire wall, 
and in other cases still, e. g. procumbent axis of S. spinosa, 
rhizome of 5. Lyallii , &c., the whole wall is uniformly cuticu- 
larized from a very early stage in the development of the cell. 
In some cases two or more endodermal cells may be found 
enclosed in a common cuticular band, the cells in such cases 
never having become isolated. In .S. Braunii the endodermal 
cells are not infrequently branched. In other cases still, e. g. 
canalicidata , the endodermal cells run across the lacuna, 
articulating directly with the more compact cortex. 
The special distal cortical cells, to which in most cases the 
endodermal cells are attached, are most commonly swollen and 
succulent and contain a large amount of chlorophyll. Very fre- 
quently these cells undergo considerable subdivision, so that a 
fairly large amount of parenchyma is found surrounding the 
distal end of the endodermal cell. In other cases these cells 
may be long and tubular, and more like those of the inner com- 
