302 Scientific Proceedings^ Bni/ul Dvblin Society. 



material and a few ants ; in none of the tiiree was the mouth blocked witli 

 clay. 



The pitclier of July 21st Wcas about lialf full of water, and contained 

 plenty of roots and ant-nest-material. 



Sometimes, but not at all commonly, other insects are found in the 

 pitchers. Tlie small black ant, Catautaciis ()ranulatus, Latr., mentioned before 

 in connexion with D. nummulnria, was found inhabiting one pitcher; winged 

 adults as well as workers were present, but they had brouglit in no clay ; the 

 adjoining pitchers of the same group had nests of Iridomyrmex. On two or 

 three occasions I have found one of the Tliysanura, usually in fully formed 

 but young pitcliers, in which ants have not yet nested. Once I found several 

 scale insects in a similarly empty pitcher. I liave never noticed dead insects 

 in tlie pitchers. 



Function of tlte Pitchers in D. rnfflesiaiia. 



The pitchers of DischicUa rafflesinna liave attracted the attention of many 

 observers ; and various tlieories have been advanced as to tlieir function. I 

 liave not been able to refer to the original articles of the older writers, but 

 liave seen two papers in the " Annals of Botany," one by Groom,' the other 

 by Scott and Sargant,^ which give a good summary of these theories. The 

 chief views which have been put forward may be given as follows : — 



(1) Beccari regards the pitchers as galls which have become hereditary, 

 and now serve mainly as ant-slielters, tlie ants protecting the plants from the 

 attacks of other animals ; or perhaps Acari, which he found in numbers on a 

 very young pitcher, may regularly visit and deposit eggs in the pitchers at 

 an early stage, thus exciting the characteristic development. 



(2) Delpiuo holds the view that the plant is carnivorous, the pitchers 

 serving to entrap insects. 



(3) Treub's view is that the pitchers serve to collect rain, and in a less 

 degree to economize the watery vapour given off in transpiration, the detritus 

 sometimes found in pitchers also serving as a food-supply. This view also 

 receives the support of Scott and Sargant, who, however, make a difference 

 between the function of the erect and pendent pitchers. " The former," they 

 say, " can have no other function than to store up the water given off as 

 vapour in transportation " ; while " the obvious function of the pendent 

 pitchers as catch-reservoirs of rain-water requires no further explanation."'' 



(4) Groom considers the pitchers to be mainly organs adapted to provide 

 shelter for the ants, on the one hand, and on the other to secure for the use of 



' Groom, loe cit. ^ Scott and Sargant, he cit. 



