i 2 Campbell \ — Observations on the Development 
strictly dichotomous, and it is only gradually that the mono- 
podial branching is established. Farmer 1 shows in his figures 
of Angiopteris the cotyledon of a more spatulate form with 
a distinct midrib and lateral veins, and in this respect 
Angiopteris would appear to differ more from Marattia than 
the latter does from most of the Leptosporangiatae where the 
dichotomous branching of the lamina is nearly constant. 
The nearly cylindrical petiole is deeply channelled upon 
the inner side and the single central vascular bundle is 
almost circular in section. While the crescent-shaped mass 
of tracheary tissue is completely enclosed by the phloem 
(Figs. 38-39), the development of the phloem is much less 
upon the inner side, and the bundle approaches closely the 
collateral type. 
The tannin-cells, which according to Farmer’s account are 
so conspicuous in Angiopteris , are also found here, but are not 
so marked. These are the shaded cells in Fig. 39. If these 
belong to the cortex, as Farmer asserts, this would bring the 
xylem of the bundle into direct contact with the ground-tissue, 
and consequently the bundle would be truly collateral. This 
point was not however investigated by me. 
The lamina of the cotyledon is similar in structure to that 
of the later leaves, differing mainly in the much smaller 
development of the mesophyll. The smaller veins have the 
xylem reduced to a few (1-3) small tracheids which are 
situated upon the upper side of the bundle. Stomata of 
the ordinary form (Figs. 35-36) occur upon the lower surface 
of the leaf. 
The Stem. 
In the older embryos, the apex of the stem (Figs. 30-33) is 
occupied by a group of relatively large cells, which at first 
seem to be pretty nearly alike ; but a careful examination of 
these led me to think that only one or two of these are to be 
regarded as properly initial cells. In the cross-section shown 
in Fig. 33, for instance, the arrangement of cells is such as to 
1 Loc. cit. Figs. 19-21. 
