74 Sykes . — The Anatomy and Morphology of Tmesipteris. 
A single vascular bundle, very like a leaf-trace in appearance but of 
rather greater bulk, enters the branch axis. In all the cases examined 
only one protoxylem group is present, but Bertrand 1 describes cases in 
which the bundle was diarch. The single bundle very soon branches into 
Figure VIII. A-G , illustrating a series of cross-sections through a fertile branch. 
A-E, through stalk of branch; F, through origin of two leaves and synangium ; G, through two 
leaves and apex of synangium ; H , tangential section through synangium at level III, showing 
phloem extending up the walls of the synangium. 
Figure IX. Surface view of line of dehiscence of synangium showing layer of thin- 
walled cells ; ep = epidermis ; c = cortex ; e — endodermis ; p — phloem ; xy = xylem ; 
st = stomata ; ped = synangium pedicel ; sss = synangial septum ; S = synangium ; ss = spore 
cavity ; d — line of dehiscence ; L = leaves ; L' = decurrent base of leaves ; /, II, III = levels in 
/"at which Figs, io, n, 12, PI. VIII, were taken. 
three (cf. Text-fig. VIII, D, and Fig. 7, PI. VIII), and the three products of 
division move farther apart and become each surrounded by a separate 
* endodermal * layer. Meanwhile the cross-sections, which were circular 
before, become more or less square, and soon two of the corners of the 
square begin to project. These corners correspond to the ridges formed by 
1 Bertrand, pp. 256 and 272. 
