96 BRUCE—STRUCTURE AND FUNCTION 
STRUCTURE OF STEM. 
In the largest specimen of R. dentata that 1 was able to 
examine, the diameter of the stem was about 1 cm. It was 
bare of tentacles, which had been thrown off with bark. The 
consistence is hard. On transverse section of an old stem 
there is visible a poorly-developed pith of small cells, a mass of 
dense wood composing the bulk of the stem, and traversed by 
numerous long, narrow medullary rays. On the outside isa 
small bark. 
Young stems show a large central pith, and just outside the 
phloem is an endodermis of five or six cells in one layer, but here 
and there there may be two layers. Outside this is a sheath of 
sclerenchyma-cells, which may in places be four or five rows 
thick. 
The cortex is composed of large irregular cells with numerous 
intercellular spaces. The epidermal cells have a thick cuticle 
and no chlorophyll. The radial walls of the cells are thin, the 
outer and inner walls thick. Beneath the epidermis is a single 
row of cells of about the same size as the epidermal cells, with 
which they alternate in position. Their radial walls are also 
thin, while the outer and inner walls are thick. 
. Gorgontas is \ike R. dentata in stem-structure. 
STRUCTURE OF ROOT. 
R. Gorgonias has a well-developed root showing a_ large 
central axis with numerous lateral rootlets. It istetrarch. The 
large root system in Roridula, which in its adaptation to 
insectivorous habit seems to me to show the most primitive 
construction amongst the Droseracez, is of interest as pointing 
to the conclusion that the acquisition of the insectivorous habit 
was not due to a difficulty in absorption from the soil through 
defect in the root-system. 
R. dentata conforms in root-features to R. Gorgonias. 
