Kekk — Dischidia rafflesiana and Dischidia nummular ia. 305 



To conclude, tlie functions of the pitcliers are : — 



1. To economize the water- vapour of transpiration. 



2. To provide shelters for ants, which in return supply the roots with food- 



material. 



Are these two species of iJisvlndia niynnecoplnjtes ? 



A myrmecophyte may be defined as a plant living in symbiosis with auts 

 to the mutual benefit of both plant and ants. Both D. numniularia and 

 D. rafflesiana come, I think, within the definition. The adult plants of neitlier 

 of these two species hold out attractions to ants in the way of special glands. 

 In this connexion, however, the discovery of an apical gland in very young 

 pitchers by Scott and Sargant is very suggestive. Probably at one stage in 

 the evolution of the plant this gland was functional tliroughout the life of tlie 

 pitcher. This might explain the meaning of tlie long, inturned tip, tlie gland 

 at its end then serving to attract ants into the interior of the pitcher.' It is 

 possible tlie very abundant secretion of nectar by the flowers may help to 

 attract ants. D. nummularia remains in flower for about three months — 

 March, April, and May — dnring which time the flowers are constantly visited 

 by Iridomyrmex. B. rafflesiana probably does not remain in flower so long, but 

 its secretion of nectar is more copious, though only available to uuts for a 

 very short time after the flower opens. 



I feel on surer ground when I say that the shelter afforded by the leaves — 

 even by the flat leaves — of 1). numiindaria, much more so by tlie pitchers of 

 D. rafflesiana, is of distinct benefit to the ants. As Iridomyrmex rarely 

 exposes itself openly, keeping for the most part in its nest or runs, it is 

 reasonable to suppose that it is subject to attack by enemies, which there is 

 some evidence to show are birds and other ants. 



The benefit, on the other hand, which the ant confers on the plant is a 

 very great one, as the materials of the ants' nest are a source of food to the 

 roots. Possibly, also, the ants may protect the plant from some enemies. 

 They always swarm out and attack the marauder when a plant is pulled down. 

 Their bite is not very severe, however ; and I have observed caterpillars 

 eating the young leaves of D. numniularia unmolested. It is even possible 

 tliat they sometimes attack animals detrimental to the plant. Eound holes 

 in the pitchers of D. rafflesiana are quite common ; and I believe they arc 



' Groom's explanation of this structure, that it acts like the inturned edge of an ink-pot from 

 which ink cannot be spilt, can hardly be the correct one, as the pitchers are fixed, ana could 

 not be reversed. 



