522 
CHRISTINE E. QUINLAN ON 
the cells are thickened on the inner and lateral walls, and thus form a hetero- 
geneous pericycle. The sclerotic groups themselves, however, never fuse to complete 
the pericycle, even in an old stem. In the old stem, traces of lignin are found in 
the walls of the oleiferous cortical cells. Secondary thickening of the cortex has 
its origin in the subepidermal region or the “ exodermis ” of Van Tieghem, and 
the radial walls of the cork cells show well-marked foldings. 
The pericyclic origin of the peripheral vascular bundles is seen more clearly in 
C. fioridus than in C. fertilis. It has been shown that the cells with U-shaped 
thickenings occur between, and in some places in a direct line with, the uniformly 
sclerotic cells, and so form part of the pericycle. The sclerotic cells with U-shaped 
thickenings are also found in the layer of cells surrounding the peripheral bundles 
on the outside. Since the peripheral bundles are seen to be inserted between the 
outer layer of the pericycle and the phloem of the central stele, it may be concluded 
that they are pericyclic in origin. 
The leaf-trace insertion on the whole resembles that of C. fertilis. The number 
of vascular bundles in the petiole varies, but is usually four or, more commonly, 
five. In no case did I find three bundles, as recorded by Gaudichatjd. As a rule, 
in each petiole, there is one large median bundle and two smaller laterals on either 
side. The median bundle enters the vascular ring through the gap, but before 
doing so it gives off laterally two strands which join the lateral bundles, before 
the latter unite with the peripheral bundles of the axis. The lateral foliar bundles 
immediately' flanking the median bundle unite sooner or later with the extreme 
lateral ones. The latter often unite with the peripheral bundle of the stem, before 
receiving the strand from the median foliar ; and in some cases there may be a 
simultaneous fusion of the strands from the median foliar bundle, the lateral foliars, 
and the peripheral bundle of the axis. At a slightly lower level anastomosis takes 
place between the peripheral bundles on the flanks of the node. The axillary bud 
receives a very minute strand from the peripheral bundle of the stem. It passes 
inside the lateral foliar bundles and gives off a smaller strand to the younger bud 
on the outside. 
The thalamus on examination shows a more regular arrangement of the bundles 
than in C. fertilis. Each of the peripheral bundles divides into two, and the number 
remains constant till the perianth segments begin to come off. After this many 
divisions take place which cannot be followed. Each sepal, petal, and stamen receives 
a median strand from the central stele and two laterals from the peripheral ring. 
There is always anastomosis between the median and the lateral bundles, but there 
is no transverse commissure between the laterals. The method of distribution is 
the same for all the floral segments except the carpels, which receive vascular 
cords from the central cylinder only. 
The young stem of C. occidentalis in transverse section is practically identical 
with C. foridus, save that the endodermis is well defined and is easily recognised 
