368 Morphological Notes . 
Treub’s view that the pitchers are water-economizers 
appears most nearly to correspond with the facts. As he 
points out, it is only in certain, and by no means inevitable, 
positions that the pitchers collect rain-water. I can only 
conclude that on the average they pay. But under all circum- 
stances they serve to preserve water lost by transpiration, 
which is one of the severest taxes the plant has to meet. 
As is well known, the pitchers of Dischidia rafflesiana con- 
tain a copious root system. This is derived from one or 
more of a pair of aerial roots, which are either derived from 
the petiole or from the stem in close adjacence (S. and S., 
1. c. 359)- The whole root system of the plant is adventitious. 
And I venture to hazard the theory that in so far as adventi- 
tious roots are not merely organs of support, their production 
is a response to a demand for water. In Plate XV, Fig. 1, 
it will be noticed that each petiolar root is applied to the 
concavity of its corresponding leaf, and in Fig. 3 it will be 
seen that as soon as the concavity becomes a pitcher the 
roots are included within it. 
The whole, if I may say so, evolutionary data, tend to 
prove then that the primary object of the pitchers is the 
supply, or at any rate economy of water. But the copious 
development of the enclosed root system, which is often matted 
with organic debris, seems to go beyond this. The researches 
of Groom (Annals of Botany, 1893, 233, 242), I think, leave 
no doubt that the roots utilize this as if it were ordinary soil 
(1. c. 227). From whence is the organic matter derived ? 
There can be no doubt that, except when in the erect position, 
the pitchers are usually almost dry. We are driven then 
to accept the suggestion of Groom based on the observations 
of Mr. H. N. Ridley, that the organic matter is carried in by 
ants (1. c. 229). 
We have therefore to deal with an adaptation of a singu- 
larly complex kind. Originally destined to store and econo- 
mize water the pitchers often imperfectly perform that function, 
and are then taken possession of by ants which supply solid 
in the place of liquid nutriment. Having begun as ‘water- 
