50 
T ho day. — Anatomy of the Ovule and Seed in 
expanded flange of the inner covering in Gneturn. The micropyle is widely 
open at the apex, but lower down, where the canal is probably slit-like, 
it may, if the comparison with Gnetum be correct, be already partly closed. 
The earlier descriptions of Cycadeoidea made 
possible only a rough comparison with Bennet- 
titfs and the mature seed of Gnetum , but the 
later described mature seeds of C. turrita 1 and 
C. Dartoni 2 make the resemblances much 
clearer. In these seeds the outer layer of the 
integument is ‘ palisaded ’ throughout, but most 
strongly at the shoulders of the seed, where it is 
expanded into five or six wings, like B. Morierei. 
At the top of these expanded shoulders there 
is a break, beyond which begins the micropylar 
tube proper ; the stony layer of the integument is 
not prolonged over the micropylar tube as was 
at first erroneously thought . 3 Thus the whole 
arrangement is quite comparable with that in 
G. africanum ; 4 the micropylar tube is even 
similarly filled with thin-walled tissue, and ap- 
pears to be a separate organ from the integu- 
ment which forms the shoulders of the seed. 
There is no nucellar beak described or figured 
in these seeds ; as they are at a stage when the 
embryo is well developed, it is not surprising 
that the relations of the micropylar tube to the 
nucellus, &c., are not well defined. 
Lignier’s description of Bennettites Morierei , 5 
also a seed with fully developed embryo, has up 
till now not been comparable with the other 
seeds, either of the Bennettitales or of Gnetum . 
In my earlier paper on Gnetum , 6 I compared 
the detailed structure of its winged integument 
with that of Gnetum and Ephedra , ‘ but it was obvious that the relations of 
the nucellus with the micropylar tube and integument in Bennettites were 
very confusing.’ The suggestions then made are strengthened by the 
current investigation of G. Gnemon\ the remarkable arrangement found at 
the apex of that seed, exemplified in Text-fig. 2, resulting frcm com- 
plicated growth-changes reminds one most forcibly of Lignier’s figures 
Text-fig. 5. Apex of 
seed of B. Morierei (from 
Lignier, 1894, relettered for 
purposes of comparison). Mi 
= micropylar tube with pro- 
jecting spurs ( Af ) comparable 
with stopper and downward 
flange in Gnetum , projecting 
over tip of integument (o). 
(The dotted line at the base of 
the flange is inserted.) g = 
space between stopper and 
beak (b) described by Lignier 
as the canal of the micropylar 
tube ; B = Lignier’s nucellar 
beak, compared here with the 
beak formed by the broken-off 
base of the micropylar tube in 
Gnetum ; sp — space between 
beak and nucellus called by 
Lignier the pollen-chamber ; 
p.c. = Lignier’s ‘ corpuscular 
mass’ in the apex of the 
nucellus comparable in position 
with the pollen-chamber in 
Gnetum. 
1 Wieland, 1911, Fig. 15 c; 1912, Pt. VI, Fig. 11. He compares this seed to Gnetum , but his 
figure of the ‘ leafy ’ seed of Gnetum seems to be based on a misconception. 
2 Wieland, 1916, p. 133. 3 Ibid., 1912, PI. VI, Fig. 6. 
4 Ibid.; see description of Fig. ii. 5 Lignier, 1894. 6 Thoday, 1911. 
