368 



CONCLUSION. 



[Chap. XVIII. 



matter, such as the bird's-nest orchis (Neottia), &c." Last- 

 ly, there is the well-known fourth class of parasites (such as 

 the mistletoe), which are nourished by the juices of living 

 plants. Most, however, of the plants belonging to these four 

 classes obtain part of their carbon like ordinary species, from 

 the atmosphere. Such are the diversified means, as far as at 

 present known, by which higher plants gain their subsist- 

 ence. 



" [Dischidia Raffleaiana, Wall., 

 Is sumetiiues doubtfully uieu- 

 tioned as an Insectivorous plant. 

 The researches of Trenb ('An- 

 naU>s du Jardin botanique de 

 Buitenzorg,' vol. 111. 1883. p. 13) 

 show that this Is not the case. 

 Dischidia grows as a cllml>lng 

 epiphyte on trees, and bears clus- 

 ters of modified leaves or pitch- 

 ers. They are of Interest mor- 

 phologically because it Is the in- 

 side of the pitcher which corre- 

 sponds to the lower surface of 

 the leaf, so that the pitchers are 

 involutions or pouchtngs of the 

 leaf from the lower instead of 

 from the upper surface as in 

 Nepenthes, Sarracenla and Cepha- 

 lotus (see Diclison, ' Journal of 

 Botany,' 1881. p. 133). The 



Citchers of Dischidia are covered, 

 oth inside and out. with a waxy 

 coating which is heaped up in a 

 curious manner round the stom- 

 ata, forming a tower-lilce struc- 

 ture round each of these open- 

 ings. There are no giuuds on 



the surface of the pitchers, and 

 the fluid with which they are 

 often partially filled Is simply 

 collected rain-water. Adventi- 

 tious roots are numerous and 

 commonly enter the cavities of 

 the pitchers. Delpino (quoted by 

 Treub) believes that the pitchers 

 serve to collect ants, &c., whose 

 dead bodies may supply food to 

 tlie roots. Treub on the other 

 hand l)elleves that the drowning 

 of ants within the pitchers Is ac- 

 cidental rather than wilful on the 

 part of the plant. He points out 

 that no arrangement for retain- 

 ing the ants exists, and that the 

 adventitious roots supply ladders 

 by which they may escape; more- 

 over the ants are as often as not 

 found alive and well within the 

 pitchers. Treub is inclined to 

 consider that the pitchers' func- 

 tion is as stores or cisterns of 

 water: but their use in the 

 economy of the i>lnnt cannot be 

 considered as denultely settled. 

 F. D.l 



