208 
Parkin.—Observations on 
ferous tubes act as agents for the conveyance from the leaf 
of plastic substances formed in the mesophyll, at least as far 
as these two plants are concerned. 
VII. A SPECIAL LATICIFEROUS SYSTEM IN THE YOUNG 
SEED OF Hevea BRASILIENSIS, Mull.-Arg. 
If laticiferous tubes have the function of conducting food- 
materials to growing organs, one might expect to find a rich 
development in the fibrovascular bundles going from the 
placenta to the ovule. On this account I was led to examine 
the developing seeds of Hevea. 
The gynoecium is of the typical Euphorbaceous type, con¬ 
sisting of three carpels united into a trilocular ovary with 
a single suspended anatropous ovule in each loculus. After 
fertilization the ovary wall becomes differentiated into two 
parts, an inner portion composed of cells, which lengthen 
greatly in the radial direction, and lignify to form the hard 
wall of the capsule, and an outer layer which retains its 
parenchymatous condition and in which a rich laticiferous 
system is developed. The laticiferous tubes are not so ex¬ 
tensive in the septa and central column bearing the placentas. 
The funicle and raphe of the developing seed are almost 
devoid of laticiferous tubes. A number of ovules and seeds 
have been examined in various stages of development, and 
only very occasionally has a laticiferous element been seen 
in these regions. The main fibrovascular bundle passing 
through the funicle and raphe to the chalaza is thus, as a rule, 
not accompanied by laticiferous vessels, at any rate by tubes 
containing caoutchouc and similar substances. 
While examining the developing seed, a somewhat singular 
development of laticiferous elements was discovered just 
beneath the inner limiting layer of cells of the inner integu¬ 
ment. These are absent from the ovule at the flowering 
stage, and only arise sometime after, when the capsule has 
reached a considerable size. 
Figures 2 and 3 show the situation and general arrangement 
