23 * 
Groom— On Disc India rafflesiana ( Wall 
they further developed Into pitchers which should serve as 
(i) traps in which to catch insects ; (2) dwelling-houses for 
ants which should In return protect the plants from the attacks 
of animals ; (3) root-protectors ; (4) water-reservoirs ; (5) 
receptacles for food-material (humus, &c.). Naturally two or 
more of these functions might be combined. 
Treub has dismissed the trap-theory because, In the first 
place, the corpses of insects are found in the pitchers in 
extremely small quantities ; secondly the insects found in the 
pitchers are for the most part living and they can easily 
escape ; thirdly there are no digestive glands within the 
pitchers. However it may be pointed out that, after all, the 
difference between the mode of action of the pitchers of 
Dischidia and of those of the indubitably insectivorous 
Nepenthes , is not so wide. Insects can and do escape from 
the pitchers of Nepenthes : they are regular nurseries for the 
larvae of mosquitos which develop in the contained liquid 1 
and subsequently fly out. I have myself seen a spider rush 
out from beneath the incurved margin of the pitcher of 
N. ampullacea . Nepenthes is by no means dependent on 
animals for its humus ; I examined scores of pitchers of 
N. ampullacea and found that most of the open pitchers 
contained decaying vegetable matter in the form of whole 
leaves or fragments of them. And, finally to break down 
the supposed widest difference between the pitchers of 
Dischidia and Nepenthes , it now appears that in Nepenthes 
they possess no ferment-secreting digestive glands, but that 
the fermentative processes are the work of Bacteria contained 
in the liquid within the pitchers 2 . Nevertheless the prepon- 
derance of living insects within the pitchers of Dischidia , and 
1 H. N. Ridley, Proceedings of the Asiatic Society (reprint, not dated). I have 
confirmed Ridley’s observations and have found that the mosquito-larvae not only 
develop in the liquid, but that the mature mosquitos escape. I plugged isolated 
pitchers with cotton-wool and suspended them on a verandah at Singapore ; on 
subsequently removing the plugs many mosquitos flew out. 
2 R. Dubois, Sur le pretendu pouvoir digestif du liquide de l’urne des Nepenthes. 
Comptes rendus de l’Academie des Sciences de Paris, Tome cxi, 1890, p. 315. 
Dubois’ work is not conclusive, but his views appear to be corroborated by the 
