in Myzodendron punchdatum , Banks et Sol. 195 
the upper part of the embryo are in the ripe seed empty and 
arranged in zones tier upon tier (Fig. 18), and look very like a 
distinct membrane (compare Fig. 19 with Fig. 20 in the Flora 
Antarctica). Longitudinal sections, however, show that these 
empty sheathing cells are organically continuous with the rest 
of the endosperm (Fig. 18). In the half-ripe seed there is a 
regular gradation in the diminution of contents from the lower 
part of the enveloping cells to the uppermost part where the 
endosperm-cells are empty. While this explanation seems to 
me to hold good for the upper part of the funicular membrane, 
a somewhat different one is required for the lower part, which 
Sir J. D. Hooker was unable to trace. In this region, owing 
to the pressure exerted by the enlarging embryo, the endo- 
sperm-cells adjacent to it suffer and are to a greater or less 
degree pressed out of shape, so that in the ripe seed the layer 
of endosperm-cells enveloping the cotyledonary end of the 
embryo may appear more or less as a thin membrane. This 
interpretation is supported by an examination of young seeds, 
in which the cells can be seen being squeezed out of shape, by 
comparison with the seeds of other plants, and by the frequent 
adherence of part of the endosperm to the embryo when the 
latter is removed bodily from the ripe seed which is naked, 
except for a small part of its surface in its apical region, where 
it is covered by a thin cellular membrane, apparently derived 
from the integument (Fig. 18, /). 
In the ripe fruit the placental embryo-sac tube, pushed, as 
has been mentioned, to one side by the enlarging seed, is still 
an open tube, though its protoplasm is reduced to a thin layer 
enclosing a large quantity of cell-sap. The cell-wall of the 
tube is, from the first, thick and of a cellulose-nature, and in 
both longitudinal and transverse sections clearly recognisable 
as distinct from the cell- walls of adjacent penetrated cells 
(Figs. 18 and 19). If after dissection the placenta and seed 
be cleared by immersion for some time in pure glycerine, or 
in oil of cloves and Canada balsam, and then examined, the 
wall and contents of the embryo-sac prolongation can be 
traced through the whole extent of the tube under a } inch 
