94 BRUCE—STRUCTURE AND FUNCTION 
become shortened until, ultimately, it has completely disap- 
peared, while those tentacles which have not undergone this 
shortening have lost the power of digestion, which would be of 
no use to them, since the head of the tentacle would not be 
brought in contact with the body of the insect after it had 
fallen on to the leaf. The glistening drop of secretion formed 
on these tentacles is, however, advantageous to the plant for 
attracting insects and capturing them. 
ACTIVITY OF THE GLANDS OF RORIDULA GORGONIAS. 
The plant experimented upon was kept in a plant-house in the 
Royal Botanic Garden, Edinburgh, at a temperature between 
50° and 60° C. The experiments were carried out during the 
months of November and the beginning of December. The 
plant was, unfortunately, thriving very badly at the time, and 
died about the middle of December, before the experiments had 
been concluded. 
The plant stood close to several plants of Aydlis gigantea, and 
although the glands seemed to all outward appearance to be 
secreting properly, the number of insects caught was exceed- 
ingly small; while the leaves of the active Byblis were crowded 
with insects. 
This might be due to the fact that Roridu/a has not the 
same attraction for insects as Aydlis, a view, however, which 
is scarcely consistent with the large number of the glands which 
in this case were all more or less actively secreting ; or, as seems 
more probable, it might be due to the plant being in bad health 
at the time. 
In order to determine whether the tentacles possess power of 
movement, I repeatedly irritated them by means of a sharply 
pointed needle, but was never able to observe any signs of 
movement, nor after placing small cubes of albumen on the 
glands did I observe any inflection of the tentacles. 
The secretion from the larger tentacles is neutral to litmus 
paper, but in one or two cases the secretion from the smaller 
glands was slightly acid. 
I placed a small cube of albumen upon one of the glands 
situated at the back of the mid-rib. After 24 hours the angles 
and edges of the tube had been rounded off, and, after a further 
