232 Groom . — On Dischidia rafflesiana ( Wall .). 
the insignificant amount of dead insects there, sufficiently 
show that the pitchers did not arise as traps for insects. 
As regards the view that the pitchers arose merely as 
quarters for a standing army of ants, there is nothing to 
support it. 
The view that the pitchers were evolved solely as organs 
for the protection of the roots, cannot be taken by itself : for 
it is obvious that the roots within the pitchers would be of no 
use unless the latter contained substances which the roots 
could absorb. 
Treub adheres to the theory that the pitchers arose for the 
purpose of storing up water. In favour of this view one can 
cite the analogy of other epiphytes which possess water- 
reservoirs (aqueous tissue of leaves, pseudo-bulbs of orchids, 
the thickened petioles of some Aroids 1 ). But on the other 
hand, the fact is that the position of the pitchers is not the 
most perfectly calculated for them to merely catch rain-water. 
With this may be coupled the occurrence of a considerable 
amount of solid matter in the pitchers. In the stage of 
evolution of the pitchers in which they were merely leaves 
with concave lower surfaces, the main or sole supply of water 
to the underlying roots would be — not pure rain-water but— - 
water running down the trunk and branches of the host and 
carrying with it solid particles. Hence one could easily 
conceive that the pitchers might have been evolved in order 
that this nutritive liquid should be stored up and made 
available for the roots. And it is quite possible that this is 
the whole rationale of the origin of the pitchers. 
Some facts, however, seem to indicate that the attainment 
of the pitcher-form has been associated with the storage of 
food brought by the ants: (1) Ants live under the leaves of 
other species of Dischidia , namely under leaves with concave 
lower surfaces : (2) D. Collyris has leaves which are more like 
fact that mosquito-larvae develop within the liquid of the pitchers and by 
Tischutkin (Ueber die Rolle der Mikro-organismen bei der Ernahrung der 
insektenfressenden Pflanzen. Ref. in Botan. Centralbl. L. 1892, p. 304). 
1 Schimper, loc. cit. 
