354 DR. WINIFRED E. BRENCHLEY ON BRANCHING 
overcome by pushing in short pins at every three sections, which made the 
structure very much stronger. The resulting rough step-like model was 
smoothed down with hot copper wire and polished off with modelling tools. 
To distinguish the different parts, the main stem was painted black, the 
branches brown, and the leaf-bases and petioles green. In the ease of 
Dr. Scott’s specimen the exact length of the original was not known, so it 
was assumed that approximately the same amount of wastage would occur in 
cutting the sections, and the model was constructed on the assumption that 
each section represented } inch length of the original stem, the enlargement 
being again two diameters. 
The University College specimen (fig. 1, p. 552) shows six leat-bases (1-6), 
and branches spring from the axils of five of them. Some of these in their 
turn bear leaf-bases, but no secondary ramification occurs. The branch in 
the axil of leaf-base no. 3 is most exceptionally large, being bigger than the 
main stem at the base, and continuing so all the way along. Dr. Scott’s 
specimen (fig. 3), though a little smaller, is much more complex. As 
before, every branch is axillary. The main stem shows a primary branch 
from the lower three of its five nodes. Two of these primary branches 
exhibit secondary ramification, and one of these secondary axes again divides, 
so that, in addition to the principal axis, there are branches of the first, 
second and third orders, axillary in every case. li seems most probable 
that the origin of both these specimens was near the top of the plant, as the 
diameter of the main axis decreases markedly from base to apex, and 
moreover the leaf-bases are very much crowded together at the summit, 
The tissues of the petioles and the branches are fully developed and do not 
seem at all embryonic in structure, thus indicating either that the sections 
are cut some little way below the actual apex of the stem, or that the 
specimens had exhausted their growth. 
One point in connection with the phyllotaxis is noticeable—the direction 
of the spiral formed by the leaf-bases on an appendage is always the reverse 
of that on the axis on which it occurs, 7. e. when the spiral on the main axis 
is counter-clockwise in direction that on the primary branch is clockwise, and 
that on the secondary appendage counter-clockwise again (ef. ground-plans 
of models, figs. 2 & 4). This arrangement was so strikingly evident that a 
number of living trees and shrubs were examined to see if a similar pheno- 
menon occurred in modern plants, but in no single instance that came under 
observation could any regularity be observed. It would be interesting to 
obtain more definite information on this point. The idea suggests itself that 
this was a regular characteristic of Lyginodendron, but this naturally cannot 
be settled until additional specimens of branching stems are available for 
examination. 
The branching of the main axis seems to disturb the phyllotaxis con- 
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siderably. That of the main axes themselves is consistently the normal 
