464 Ridley.—Symbiosis of Ants and Plants. 
siderable number on September 29, after a heavy rain shower in the 
morning, I found the greater number quite dry inside, three or four with 
a drop or two of water, and one or two full or nearly so. Groom showed 
by experiments made in the Botanic Gardens, Singapore, that the roots 
inside the pitchers absolutely did absorb the water, 1 and further that a con¬ 
siderable amount of earth and humus was found in the pitchers ; and though 
part of this was no doubt debris of bark from the upper part of the tree 
washed in by storms of rain, there was a quantity of material which could 
only have been brought by ants. In the plants which he and I examined, 
we found clay similar to that of the soil at the foot of the tree. Without 
doubt the ants had carried this soil into the pitchers and made nests 
therein. Unfortunately we did not investigate what the species of ant was 
that was utilizing the pitchers as nests, and the tree and Dischidia on which 
these observations were made has long gone. 
On examining the pitchers of the Dischidia on the Durian tree above 
mentioned, I found that in most branches of pitchers a touch produced an 
exodus from the mouth of the pitcher of numerous little vicious ants, which 
appear to be Technomyrmex brunneus , but on opening the pitcher from 
which they issued, no humus or any trace of a nest was found and no larvae 
or pupae. The ants appeared to be clustered round the upper end of the 
cup, behind the incurved lips. Nests of this ant were, however, found under 
the bark of the tree where loose and among the masses of rhizomes of the 
Drymoglossum and other such spots. They were made of thin brown 
walls, apparently of vegetable debris, with supporting partitions. The whole 
tree swarmed with myriads of these ants, which run about on all the branches, 
and were to be seen busily engaged with coccids on the leaves of the 
Durian. 
In a good many cases, especially where the slender twining stem 
hung down below the bough it was climbing on, there were no ants in the 
pitchers, and in these were often small cockroaches and other insects. 
It is clear that this species of ant does not care to make its nest 
in the pitchers; indeed, many of the nests on the tree were much too large 
to be included in a pitcher, and as the ants were occupying the tree in 
immense numbers, and very vicious, no other species of ant would be able 
to make a lodgement in the pitchers. 
What was the reason, then, of their visiting the interior of the pitchers ? 
They were absent from the pitchers containing water, even in small 
quantity. The inner surface of the pitcher is lined with wax, and it seems 
probable that the ants were engaged in collecting this. One may compare 
this with the recurved £ bud-bract 5 of Macaranga triloba and the wax 
deposits on the back of the young leaf of M. hypoleuca , both of which are 
visited by species of ants, apparently collecting or eating the wax only. 
1 Annals of Botany, vol. vii, p. 227. 
