Dischidia rafflesiana {Wall.). 247 
Dischidia rafflesiana is also referred to in recent works by 
Gobel 1 and Schimper 2 . 
Our own object has been to make a careful anatomical 
study of the pitchers, and of other organs of the plant, so far 
as seemed necessary for purposes of comparison. Although 
the morphology of the pitchers appeared well-established, 
a study of the histological structure at different stages was 
likely to afford additional evidence of value. We also 
anticipated that a detailed investigation of structure would 
throw considerable light on the functions to which the organs 
are adapted, and in this anticipation we have not been dis- 
appointed. As usually happens, other points of interest arose 
during the investigation. 
Structure of the Stem. 
Before proceeding to compare in detail the anatomical 
structure of a pitcher with that of a normal foliage-leaf, it will 
be desirable to describe, very shortly, the anatomy of the 
stem, in order that the relations of the appendicular organs to 
the axis may be understood. 
The stem shows the structure usual in Asclepiads. The 
vascular cylinder, in the young condition especially, is sharply 
marked off from the cortex, the innermost layer of which 
forms a starch-sheath or endodermis. The vascular bundles 
are only distinct from each other while quite young. The 
inter-fascicular tissue soon becomes completely converted 
into xylem, which forms a continuous ring surrounded by a 
circle of very numerous groups of normal phloem. As in all 
the Asclepiadeae, internal phloem is also present 3 , and is in 
fact considerably more abundant than that in the normal 
position. The groups of internal phloem show no constant 
relation to the protoxylem-elements. They are separated 
from the inner edge of the wood by at least two layers of 
parenchyma. 
1 Pflanzenbiologische Schilderungen, i. pp. 230-236. 
2 Die epiphytische Vegetation Amerikas, p. 22. 
3 Cf. Treiber, Ub. d. anat. Bau des Stammes der Asclepiadeen, Bot. Centralblatt, 
Bd. 48, 1891. 
