463 
Ridley.—Symbiosis of Ants and Plants. 
D. coccinea , ants’ nests are almost invariably found, but one would have 
little doubt that the peculiar shape of the leaves in these plants is primarily 
adapted for the protection of the roots from drought, and the adoption 
of them as a suitable nesting-place by ants is a secondary function. 
Their relationship with ants is in fact very similar to that in the case of 
Platycerium, and only differs from that of Korthalsia in the actual advantage 
derived from the presence of ants in the two former plants. 
The habit of Dischidia Rafflesiana is somewhat peculiar. Indeed I do 
not know an epiphyte which at all resembles it. As Groom says, it is 
specially fond of decaying trees—perhaps it would be clearer to say dying 
trees. Its long slender stems creep along the branches, but also pass from 
branch to branch, and very frequently hang down for some distance. The 
trees it prefers are undoubtedly half-dead trees with few leaves, so that the 
plant is most fully exposed to the hot sun. In such a habitat it makes rapid 
growth, forming a kind of network over the tree, and the pitchers are yellow, 
or soon become so, the same colouring exactly as D. collyris which grows 
on tree trunks in full sun. If, as sometimes happens, the Dischidia seed 
alights on a shady tree, it grows and develops the long stem and pitchers, 
but in this case the stem and pitchers are green. It does not, however, 
make nearly as good a growth in a shady tree, and one never sees such 
a tree filled with it as one does in an open exposed tree. 
The plant is common especially on our sea-coasts in hot exposed places, 
but disappears entirely inland, and is quite absent from the forests of 
the plains and hills. I have, however, found it at an altitude of about 
3,000 feet in mossy spots on Mount Ophir, but on no other mountain. The 
pitchers here were green. Mount Ophir, however, contains a number of 
plants more commonly associated with seashores and not met with in the 
intervening country, and I think there is reason to believe that at no very 
distant date, geologically, this mountain was a separate island, and that the 
remains of its seashore flora have survived on its xerophytic upper slopes. 
The object of the pitcher-shaped leaves has constantly been discussed, 
and it is not my intention here to consider their physiological functions, 
except so far as relates to their connexion with ants, in fact to their 
supposed myrmecophily. 
I may, however, refer to the various functions that have been attributed 
to them. Delpino thought that the plant was carnivorous, that the pitchers 
caught insects which were drowned in the water contained in them after 
the manner of Nepenthes. As only a very few of the pitchers ever contain 
more than a drop or two of water, and insects do not appear to enter those 
that do, this theory may be at once dismissed. A theory that they are 
actual water-vessels containing water derived from rain, and that the roots 
obtain their water in this way, is somewhat negatived by the fact that a large 
proportion of the pitchers do not contain water. On examining a con- 
