Notes . 
1 1 1 
not been found opposite the three main ribs. The bundles are embedded in 
the inner, denser zone of the sarcotesta. These sarcotestal strands were evidently 
complete bundles with phloem as well as xylem, and from the best-preserved 
examples it appears that the xylem was of mesarch structure. The second vascular 
system of the seed (already observed by Hooker and Binney and by Oliver *) runs 
through the contracted zone of tissue lying between the sclerotesta and the membrane 
of the megaspore. We regard the tissue in question as representing the nucellus, 
which appears in this seed, as in Stephanospermum , described fully by Prof. F. W. 
Oliver 1 2 , to have been free from the integument, from the chalaza upwards. In 
good specimens there is a distinct layer of cells, like an epidermis, limiting the 
nucellus on the outside, just as is the case at the free tip of the nucellus in a modern 
Cycad and still more closely resembling the nucellar epidermis of Stephanospermum 3 . 
This specialized layer of cells, which appears to be continuous with the epidermis 
of the pollen-chamber, can be traced the whole length of the nucellus from the 
chalaza upwards, and not merely in the upper part as in Cycads. Hence it is 
clear that the internal vascular system must be regarded as belonging wholly 
to the nucellus and not to the integument as described by Miss Stopes in Cycas 4 . 
The nucellar vascular system is rather complex in its arrangement. Towards 
the base, where the nucellar vascular tissue springs from the chalazal strand, it 
forms for some distance a practically continuous sheath of tracheides; further up 
the seed the tracheides, which are much flattened tangentially, range themselves 
in more or less definite but still crowded longitudinal strands, which are connected 
by transverse anastomoses running in a tangential direction. There is no evidence 
of phloem in connexion with the nucellar tracheides. The nucellar system has been 
traced through the whole length of the nucellus almost to the base of the pollen- 
chamber, and indications of tracheides have been detected even in the beak of the 
pollen-chamber itself. 
The tracheal system of the nucellus springs from the upper end of the chalazal 
strand, where the latter terminates at the junction of sclerotesta with nucellus. The 
connexion of the outer, sarcotestal system with the chalazal strand has not yet 
been traced, but from the position of the bundles, the junction must have been 
as much as 4 mm. below the base of the nucellus. 
The tracheides, especially those of the chalazal bundle and of the sarcotestal 
strands, show, in longitudinal sections, the fine scalariform markings characteristic of the 
primary tracheides in Medullosa, a point of agreement on which we lay some stress. 
The pollen-chamber, already indicated in some of the figures of Hooker 
and Binney 5 , was described and more fully illustrated by Williamson 6 . The 
pollen-chamber itself forms a wide dome 2-5-3 mm - i n diameter at the base. We 
have to add the new fact that this was provided at the top with a narrow' beak 
or canal, not more than 300 n in diameter. Curiously enough, this interesting 
1 Structure and Affinities of Stephanospermum , p. 391. 
2 Loc. cit. 3 Loc. cit., PI. XLIII, Fig. 21. 
4 On the Double Nature of the Cycadean Integument, Ann. Bot., vol. xix, Oct. 1905. Beitrage 
zur Kenntnis d. Fortpflanzungsorgane d. Cycadeen. Flora, Bd. 4, 1904. 
5 Loc. cit., PI. IV, Figs. 7, 8, and 12. 6 Loc. cit., PI. XIII and XIV, Figs. 113-115. 
