60 Transactions of the Boyal Society of South Africa, 
In a previous paper on Boridula dentata I described two special 
features of its biology, viz. : — 
1. That it was inhabited by spiders {Syjicema marlothi Dahl.), which, 
unimpeded by the viscid secretion, move about freely on the plant and 
prey on the insects captured by the leaves ; and — 
2. That an hemipterous insect, viz., Pameridea roridnlce. Eeuter, 
which was equally immune against the viscid secretion, assisted in the 
pollination of Boridula by piercing the irritable connective of the anthers 
for the sake of its sugary contents, thereby producing the sudden turning 
of the anther and the ejection of its pollen. 
I am now able to describe some experiments, which demonstrate that 
the viscid secretion does not possess any digestive properties, and that 
Boridula is therefore not an insectivorous plant. 
The Structure of the Glaiids. — The leaves of both species of Boridula 
bear numerous stalked glands on their margins and on the midrib of the 
lower sides. While in B. Gorgonias the margin of the lanceolate leaf is 
entire, it is provided with long, narrow teeth in B. dentata, the teeth 
bearing the so-called tentacles (stalked glands) especially near and at 
their apex. The stalks are of different length, those of the terminal glands 
being up to 8 mm. long, while those situated on the margin of the leaf 
between the teeth are generally only 2-3 mm. long. There are no glands 
on the upper side of the leaf, but on the basal portion of the leaf occur 
numerous unicellular hairs, on the upper side as well as on the lower one. 
The structure of the stalk and glands was first described by Darwin,! 
who recognised, even on the dried specimens, that they showed no signs 
of inflection, and that, consequently, they are not irritable and movable, 
resembling in this respect the stalked glands of Drosophyllum. He also 
found that neither the stalks nor the glands possessed any tracheids 
(called by him spiral vessels) and that there were no sessile glands corre- 
sponding to the digestive glands of Drosophyllum, but as it was quite 
possible that the stalked glands might perform the treble duty, viz., 
secreting a viscid as well as a digestive fluid and absorbing the products 
of digestion, as is being done by the tentacles of Drosera, this difl'erence 
from Drosophyllum did not affect the possibility of the insectivorous nature 
of the plant. To Darwin's description of the structure of the glands I 
have only to add that the gland consists of an external layer of large 
secreting cells (secreting mantle) and an internal cylindrical body, which 
is merely a continuation of the tissue of the stalk. The cells of the 
secreting mantle are polyhedral in outline, with thick lateral walls, but 
without projections and intrusions into the lumen like those of Drosera. 
The contents of the younger glands are of a yellowish green colour like 
* Annals of Botany, vol. xvii., No. 65, 1903. 
f Darwin, Ch., Insectivorous Plants. 
