Gnetum Gnemon , with Notes on Gnetum funiculare. 49 
attention to the resemblances in their seeds . 1 If there is any force in this 
comparison, it is certainly augmented by the structure of the mature seed 
of G. Gnemon. 
Although it is not desirable to draw from these resemblances any con- 
clusions as to affinity, it is at least possible that the more easily investigated 
modern seeds may throw some light on the ffiksils, and it may well be that 
common ancestors are responsible for some of the similar features. The 
remarkable growth-changes now described in the development of the seeds 
of Gnetums may help us to interpret the differing arrangements described 
in the various Bennettitalean seeds, and it is at least conceivable that these 
differing arrangements are to be ascribed to the varying stages of maturity 
at which the seeds had arrived. 
A detailed comparison between some of the Bennettitalean seeds 
described up to that time and the seeds of Gnetum was made in a former 
paper , 2 and the recent descriptions of Cycadeoidea by Wieland and Seward’s 3 
account of the small ovules of Williamsonia scotica 4 seem to corroborate 
these early attempts. 
In the small ovules of W. scotica the apex of the nucellus is composed 
of radiating rows of cells, and in some cases there is no sign of any disinte- 
gration and no pollen-chamber . 5 In other cases there appears to be a small 
space at the apex, the sides of which extend upwards as a £ shrivelled beak- 
like prolongation ’, 6 suggestive of the pollen-chamber of Gnetum, with its 
thickened and indurated walls, which in longitudinal section are seen pro- 
jecting upwards like a minute beak. The seeds were not sufficiently well 
preserved, and probably too immature 7 for much differentiation in the 
integument. Originating near the base of the seed, Seward found in 
longitudinal section £ two strips of indistinct, thick-walled and short cells 
which have no epidermis and are almost certainly portions of a tissue which 
was originally broader. At a higher level the short cells become rather 
larger and much longer ’, 8 and are better preserved. These loose strips of 
tissue may represent the thickened fibrous layer of an integument like that 
of Gnetum , the rest having failed of preservation. At a higher level these 
strips approach the nucellus and join with it : this level would correspond 
with that of the origin of the inner integument in Gnettim , and, as in 
Gnetum, an expanded tissue is found over the shoulders of the seed, com- 
posed of thickened and radially elongated cells limited by a well-defined 
and characteristic epidermis. This epidermis ceases above the shoulders of 
the seed, just at the level where the middle covering ceases and we find the 
1 Sykes, 1912, p. 217 ; Berridge, 1911, p. 140; Thoday (Sykes), 1911, pp. 1125-30; Thoday 
and Berridge, 1912, pp. 978-9. 
2 Thoday, M. G., 1911, pp. 1125-30. 
4 Seward, 1912. 
6 Ibid., Fig. 18, PI. II. 
8 Ibid., pp. no- 11. 
3 Wieland, 1912, Fig. 2. 
5 Ibid., Fig. 3 D, p. in. 
7 Seward, 1912, p. 115. 
E 
