ii24 Thoday .— The Female Inflorescence and Ovules of 
VII. Comparison of the Female ‘Flower’ of Gnetum with that 
of Welwitschia. Primitive Features. 
The ovule of Gnetum , while in some respects, at any rate, not so 
primitive as that of Ephedra , is certainly more primitive than that of 
Welzvitschia. It is not intended now to enter into a comparison with 
Ephedra , as some work on that species is in progress. 
The differences between the general foim of the ovule in Gnetum and 
Welwitschia are probably dependent largely on the different positions of 
the two. The ovule of Welzvitschia is closely appressed in the axil of 
a bract, and it is therefore from the beginning bilaterally compressed. 
Hence the bilateral symmetry of the outer covering, both external and 
internal, with its two wings, each traversed by one large group of fibrous 
cells and one vascular bundle. The inner integument and nucellus still 
retain the probably more primitive radial symmetry. The ovule of Gnetum , 
which is not laterally compressed, but protected all round by the nodal 
cushion and its outgrowths, is radially symmetrical, and the fibrous cells in 
the outer integument form an uninterrupted layer which has an outward 
projection corresponding to each vascular bundle. 
Both Welwitschia and Gnetum have two integuments; the outer is 
free, the inner is in the mature ovule fused for about two-thirds of the 
length of the ovule, while its free apical portion forms the elongated micro- 
pylar tube with its characteristically cuticularized lining. There was no 
material of Welwitschia young enough to show whether in the earlier 
stages, here as in Gnetum , the inner integument arises near the outer from 
the base of the seed. The outer integument in both .seeds has a bundle 
system throughout its length, but the small bundles supplying the inner 
integument terminate at the base of the free portion in Welzvitschia , while 
in Gnetum (africanum ) they are well developed and run for a short distance 
into the base of the free portion. This greater development of the inner 
system of Gnetum , also the more complex outer integument with its stony 
layer and the development of a pollen chamber, are all probably primitive 
features which mark the wide gap between the two genera. 
The short free apical portion of the nucellus in Gnetum is also in 
great contrast with the elongated apical region of the nucellus in Wel¬ 
witschia. This latter is probably a specialized development to form a 
spacious brood chamber for the embryo, and may be regarded as a step 
towards the Angiosperms. 
An attempt has recently 1 been made to show that the Welzvitschia 
ovule is built up on the same primitive ground plan as such a seed as Lageno- 
stoma. It will be seen that all that has been said applies with still greater 
force to Gnetum the prolongation of the inner system of strands into 
1 Sykes, 1910 (1). 
