Gnetum Gnemon , with Notes on Gnetum ftmiculare . 39 
becomes triangular (Photo 2, PI. I), because of the ingrowth of the cells of 
the columnar epidermis ; here one or two of these cells, and a little lower 
many of them, are transversely divided (Photo 3, PI. I). Farther down, the 
lumen widens for a short space, and becomes a narrow oval, but very soon 
it narrows again (as seen in Text-fig. 1). This transitory wider lumen 
only shows that the changes which accompany closure begin first or proceed 
fastest at the upper and lower ends of the thickened region of the micro- 
pylar tube. In the lower part of the thickened region the lumen is quite 
narrow, is filled with mucilage, and its epidermal cells are both greatly 
elongated and subdivided into rows ; the sub-epidermal cells also are 
divided radially. The papillae produced by the outer epidermal cells 
project more freely outwards, and some of the cells below this outer 
epidermis are dividing radially. 
The next section figured (Photo 4, PI. I) cuts the tip of the outer 
integument (middle covering), which is buried in the hairs at the base of the 
thickened region of the micropylar tube. The tip of the outer integument 
is fringed with papillate cells with thickened, often slightly lignified, walls, 
which tend to aggregate into groups, and are shown in the photo at X. 
The hairs of the edge of the inner integument are often prolonged between 
them so that they appear in section as free groups of cells surrounded on all 
sides by hairs. It is difficult or impossible even at this stage to make out 
clearly the line of separation between the tip of the outer integument, 
micropylar tube, and hairs ; the epidermis of both coverings being papillate, 
they fit closely together. 
Some way below the level of the tip of the outer integument the 
lumen of the micropylar tube widens, and the elongated lining cells 
gradually resume their regular shape. The lumen is at first triangular 
(Photo 6, PI. I) and then enlarges to form the large cavity surrounding 
the apex of the nucellus. Into this cavity projects the shrivelled tip of 
the nucellus with its indurated walls (Photo 16, PI. I), to me reminiscent 
of Prof. Seward’s description of the small nucellar beak in W illiainsonia 
scotica } 
In this ovule there is no sign of lignification of any of the tissues of the 
outer integument, the inner layer (which ultimately develops into a strongly 
lignified zone of cells like that described in G. africanum ) being here com- 
posed of small closely compacted cells, isodiametric in transverse section. 
There are already signs of radial growth on the shoulder of the outer 
integument to form the expanded region found in the older seed. The 
other small ovules examined by transverse section differed only in detail 
from the one chosen for the above description. 
Other small ovules were cut in longitudinal section. One showed as 
yet no sign of the formation of a flange or thickened region or of the 
1 Seward, 1912, p, 1 12 . 
