i9 
Phytogeny of the Cyperctceae. 
level, the small lateral amphivasal strands are seen to pass divergently 
obliquely inward and upward, where they anastomose with similar strands 
from adjacent cortical bundles, forming a dense circular plexus of amphi- 
vasal strands, to which are added strands from the peripheral zone of 
proper cauline bundles, which here bend more or less sharply inward 
to pass into the base of the next internode. A little higher up (Fig. 8) 
we find the general anastomosis extending to the remainder of the 
bundles, practically all of which assume the amphivasal character for 
at least a short distance at some part of their course through the nodal 
complex. The latest evidence of nodal irregularity, as we pass upward 
into the internode, is to be seen in the deeper-seated medullary bundles. 
The central strand from the original cortical bundle passes upward and 
sometimes slightly outward into the leaf-sheath. In other words, it 
is a bundle of the leaf-trace. From the circular plexus already described 
are developed new peripheral strands which pass upward as the cortical 
bundles of the next internode. 
It appears that there is a remarkable constancy in the number of 
cortical bundles in the several internodes of a given plant, and, indeed, 
of a species. However, the number of cauline bundles usually decreases 
considerably from the base upward. Thus, in an average specimen of 
S. cyperinus , the cortical bundles numbered about forty in each internode ; 
the cauline bundles in the first internode were eighty-seven, in the second 
eighty-two, in the third seventy-six, in the fourth seventy, in the fifth 
sixty-six, and in the sixth (just below the inflorescence) sixty-eight. In 
the first branch of the inflorescence there were twenty bundles, and in 
its subtending bract thirty, while in the main axis above this branch 
there were thirty-five bundles. 
In Dulichium we find the fibro-vascular system of the Cyperaceae 
occurring in its simplest form, and a study of the course of the bundles 
in this group may lead to a clearer conception of the state of things 
in the highly complicated Scirpns cyperinus. Here the bundles of the 
internode are arranged in two circles only. The outer bundles alternate 
with the large air-spaces, and are clearly cortical bundles. The inner 
circle constitutes the cauline system. At the nodes there is formed 
a circular plexus uniting all of these bundles by amphivasal strands. 
These strands are given off from the bundles almost at right angles, 
and consequently there is little or no evidence of amphivasal bundles 
in the transverse section. A section through the upper part of the 
node shows three series of bundles — the outer series continuous below 
with the cortical series, but now passing off into the leaf-sheath ; the 
inner series continuous below with the cauline series, and itself the 
cauline series of the next higher internode ; the middle series, newly 
derived from the circular plexus, and constituting the cortical series 
C 2 
