234 Lang. — S Indies in the Morpho/ogy and 
to depart (c). As the departure of the trace rapidly takes place the internal 
group of tracheides passes out through the leaf-gap and, along with an arc 
of tracheides continuous with the additional secondary xylem of the stele, 
constitutes the xylem of the base of the branch (d). This becomes 
arranged to form a definite stele, at first with a gap opposite to the 
subtending trace (e). This gap closes, and in F the small branch stele is 
seen in the cortex beside the main stele ; the gap in the latter is now 
closing. Comparison of A and D will make it clear that the origin of the 
vascular supply to the first branch was similar. 
The special interest of this specimen lies in the need of vascular 
connexions for the branch affecting the stele of the stem before the 
departure of the subtending leaf-trace, and in the resumption of active 
secondary thickening producing xylem to which another portion of the 
vascular supply to the branch is connected. 
The fifth branching specimen (Phot. 37) was incomplete, the branch 
itself having been broken away. It was met with accidentally when cutting 
the basal region of a plant longitudinally. The specimen shows, however, 
the relation to the leaf-trace of the commencing tracheidal supply to the 
branch. The photograph shows the arrested end of the main axis, the 
departing leaf-trace, and the leaf-gap above it. The endodermis was 
completed at once on the departure of the trace. The latter itself is small, 
but from just above the level of its departure from the stele adaxial xylem 
to supply the branch has been developed. The tracheides of this adaxial 
xylem are comparatively short and wide. Just below the broken surface 
indications were evident of the arrangement of this xylem to form the stele 
of the branch. 
If the several branched specimens of B. Lunaria described above are 
compared, it is evident that, while they present considerable differences in 
detail, the vascular connexions of the branch follow the same general plan. 
In considering them it is essential to bear in mind that the branch had its 
origin in a vestigial axillary bud called into activity by the arrest of the 
normal apical growth of the main axis. While the tissues laid down in 
the further growth of the bud itself will be strictly primary, any vascular 
connexions established in the region below the vestigial bud, either with 
the subtending leaf-trace or the stem stele, must be due to subsequent and, 
in a sense, secondary changes. This will be more marked when the vestigial 
bud called into activity is situated on a quite mature region of the rhizome 
some distance from the apex, and least so when the lateral growing point 
affected is close to the apical meristem of the main axis where the tissues 
are still immature. 
Direct evidence in favour of the view just expressed could only be 
obtained from the study of buds in various stages of their growth into 
branches. The facts regarding the relations of the mature branches are, 
