380 MR. H. M. CHIBBER ON THE MORPHOLOGY 
INTERPRETATION OF THE MORPHOLOGICAL AND ANATOMICAL 
STRUCTURE OF THE PLANT. 
The plant is a liane climbing by roots. It must have owed its origin, like: 
all lianes, to “ struggle for light assisted by abundance of moisture” *. Its 
xerophilous structure, as will be presently seen, points to its having occupied 
the summit of tropical rain-forests, fully exposed to the influence of 
strong light as well as strong insolation f. 
First of all, as regards the xerophilous points in structure, the glossy and 
coriaceous nature of the leaf-suiface is intended to reflect strong light 
falling on it. The strongly developed jacket of aqueous tissue enveloping 
the mesophyll serves to cut off to a certain extent thermal rays from 
reaching the latter. Tt also serves to store up water against dry days. It 
is significant that the upper layer of this jacket is thicker than the lower 
layer. The irregular doubling of the palisade is inexplicable, save as a 
vestigial character. If then we are right in assuming the prototype of 
this eultivated plant to have possessed a regular double layer of palisade, 
cells, we have here a character which is always co-ordinated with strong 
illumination. Absence of stomata from the upper surface points, in con- 
Junction with the other characters, to the horizontal disposition of the leaves 
in an environment where the dangers of excessive heat and light come from 
above, and not beneath as is the case with lithophilous vegetation. 
Of the contents, mueilage $ and ethereal oils |, both of which are abundant, 
concurrently point to the plant attempting to reduce transpiration and 
mollify the heat to whieh it must have been exposed. It is noteworthy, in 
connection with the secretory cells that store up if not manufacture ethereal 
oil, that in the stem and the petiole they are particularly abundant in the 
* A. F. W. Schimper’s * Plant Geography,’ Engl. ed. p. 309. 
T “In structure of leaf and stem some lianes recall xerophwtes; it seems quite natural 
that lianes should be exposed to the possibility of losing more water by transpiration than 
can be balanced by supplies from the root, and hence should be structurally adapted to 
provide for this contingency " (Warming, ‘ (Ecology of Plants, Engl. ed. p. 91). 
“ According to the investigations of Haberlandt and others, plants in Javanese rain-forests 
and possibly in the higher storeys of tropical rain-forest in general, are exposed to conditions 
far more extreme than are experienced by European vegetation. ... This explains the 
remarkable fact that many plants in tropical rain-forests exhibit protective devices against 
excessive transpiration similar to those displayed by xerophytes " (Warming, p. 344). 
ў “ Voluminous peripheral water-tissue checks the penetration of heat rays rather than 
of luminous rays, and thereby retards transpiration in addition to acting as a water- 
reservoir” (Warming, p. 121). 
$ “Mucilage absorbs water readily, but parts with it very slowly, and is therefore 
manufactured by xerophytes in various organs...” (Warming, p. 120). 
| * These oils evaporate more readily than water and surround. the plant with aromatic 
air.... ethereal oils diminish insolation and consequently transpiration” (Warming, 
p. 107). 
