Notes. 
229 
•broadly ovate. And on such leaves only the two petiolar nectaries 
are found h The present observations relate to the petiolar nectaries 
of Aleurites. 
Each nectary is a green, stalked, shallow basin, the concavity of 
which is tinted red. The secreting cells which line the basin, form 
a single layer of palisade-like cells. The general cuticle is preserved 
over these, and the secretion emerges through splits in it. The 
main body of the basin is composed of an anastomosing system 
of conducting parenchyma and ground-parenchyma. The cells of 
the latter are larger and stain less deeply than those of the former. 
The conducting parenchyma is roughly arranged in a fan-like manner 
beneath the secreting layer. But at least one layer of cells differing 
from both types of parenchyma mentioned, is interposed below the 
secreting layer. Its cells are united to form a layer in which there are 
no intercellular spaces. Lower down towards the stalk of the nectary, 
the conducting parenchyma-cells surround successively tracheides and 
spiral vessels, and then complete bundles. In the stalk itself the 
vascular bundles roughly form a ring which divides the ground-tissue 
into a ‘ cortex 1 * * * 5 and a ‘ pith . 5 
In the petiole there are numerous very large laticiferous tubes 
which send off a few (about five or six) narrow branches into the 
nectary. These finer tubes give off few or no branches in the nectary, 
and some of them end bluntly under the secreting layer. Owing to 
their poverty in numbers and unbranched condition, the anatomical 
connexion between the tubes and the secreting cells is very incom- 
plete. The secreting cells contain proteids, sugar, a red colouring- 
matter (a compound of tannin ?), tannin, but no starch. In the ground- 
parenchyma starch, tannin, and crystals of calcic oxalate occur. The 
conducting parenchyma contains sugar, but no starch or crystals. In 
the laticiferous tubes tannin is found, but no starch. 
Darkening the nectaries of leaves on the plant or of excised leaves, 
or darkening the whole leaves, caused a gradual disappearance of the 
1 This interesting correlation of the lobing with the occurrence of marginal 
glands in the angles is also well illustrated by three species of Croton growing 
wild in Hong Kong. In Croton lachnocarpum (Benth.) the leaves are serrulate- 
crenate, and at the serratures are small stalked glands directed downwards. In 
Croton chinense (Benth.) the leaves are serrate or entire, and the glands are fewer 
and smaller. Finally, in Croton Hancei . (Benth.) the leaves are entire or minutely 
serrate, and each leaf has occasionally two minute glands at the base of its lamina, 
sometimes even these are absent. 
