224 ORR—AESCHYNANTHUS CHORISEPALA. 
and are only slightly coherent at the base. They are linear or 
linear oblong in shape with obtuse apices bearing a few glandular 
hairs. 
Many of the leaves of this new species of Aeschynanthus 
from Yunnan present an unusual appearance. They are tough 
and leathery in consistency, and are characterised by the 
presence of numerous elongated slits in the lamina, which, in 
the specimens examined, are often so regular in their arrangement 
as to suggest that their formation is not wholly fortuitous. 
In many of the leaves, the slits—to the number of six or eight 
—are present on each side of the midrib, following roughly the 
direction taken by the lateral veins, but, in some cases, crossing 
them. In other leaves the slits are more elongated, and run 
from base to apex of the leaf, parallel to the midrib, and often 
contiguous to it. The perforation is not always complete, and 
the upper epidermal layer then appears as a transparent skin 
over the groove. 
With a view to determining the mode of origin, and purpose, 
if any, of these slits, the structure of the leaf was examined in 
detail. In the arrangement of its tissues this leaf conforms 
closely to the leaves of other Gesneraceous species. The upper 
epidermis is many-layered, and specially adapted for water- 
storage. The outermost layer is strongly cuticularised, and this 
layer is further protected by a centrally placed “ floor’’ of 
cells which have the walls adjacent to the water-containing 
cells thickened in a manner similar to those of the outermost 
epidermal layer. Pits are present in this thickened layer, and, 
by their agency, a supply of water reaches the underlying 
tissues. These consist of a narrow band of chlorophyll-con- 
taining cells, rich in clustered crystals of calcium oxalate, and 
several layers of spongy parenchyma, containing little or no 
chlorophyll, and possessing curious tube-like protuberances 
on their walls. The under epidermis is also strongly cuti- 
cularised, with stomata and numerous stalked glands, the latter 
situated in shallow circular depressions. The cell-walls under 
these glands are thinner, and, together with the stomatal 
openings, constitute points of weakness where the slits might 
01 : 
Neither the configuration of the epidermis, nor the con- 
struction of the underlying tissues, suggest that the formation 
of the slits is other than accidental, and they probably owe their 
origin to an excessive loss of water from the tissues of the leaf. 
Such “ Cracks due to drying ”’ are mentioned by Solereder.* 
Drying of the leaf brings about the rupture of the lower 
epidermis, probably at some point of weakness, and the exposure 
* Solereder, Syst. Anat. of Dicotyledons, Engl. Ed. (Oxford Press), ii, 1088 
