Gnetum africanum , with Notes on Gnetum scandens. 1123 
parable with the ‘ lysigenous * region described in G. Gnemon by Miss 
Berridge. 
In the above series of sections it will be seen that some of the cells 
composing the micropylar tube are already lignified, especially the radial 
rows of cells derived from the inner epidermis. Lignification of these 
often begins on on§ side only, as in Text-fig. 15 C. Fig. 9, PI. LXXXVI, 
shows a transverse section through the micropylar tube of an older ovule, in 
which there is a solid central core of lignified cells surrounded by a zone 
of regular thin-walled cells. Presumably this solid core was derived from 
the radial rows of cells closing the micropyle and formed by the division 
of the epidermis, while the regular zone of cells outside (s.C.) is the sub- 
epidermal layer. 
In none of the ovules of G. africanum examined was the whole 
tube lignified as in the mature ovule of G. scandens (Fig. 12, PI. LXXXVI). 
VI. The Abortive Ovules of the Male Inflorescence of 
G. SCANDENS. 
The abortive ovules of the male inflorescence resemble those of other 
species of Gnetum. The nucellus is undifferentiated and composed of thin- 
walled cells with large nuclei. The outer covering 
contains many fibres and is obviously homologous 
with the outer covering in the fertile female flower. 
The inner covering appears to be generally homo- 
logized with the inner integument, the outer integu¬ 
ment being absent. I have no evidence one way 
or the other, except that the general form of the 
inner covering in the abortive ovule of the male 
inflorescence is more comparable with the outer 
than the inner integument of the fertile ovule, 1 as 
will be seen from the figure. 
On the other hand, Karsten 2 states that the 
middle envelope always appears in a rudimentary 
condition during the development of the abortive 
ovules, and Lotsy 3 also makes a similar statement, 
though in the figure which he gives of the developing ovule the rudiment 
of the middle envelope is almost negligible. 
1 Cf. Welwitschia , Sykes, 1910 (1), pp. 207-8. 2 Karsten, 1893, (1) and (2). 
3 Lotsy, 1899, Fig. 14, PI. II. 
Text-fig. 16. Abortive 
ovule from male inflorescence 
of G. scandens . 
