Internal Phloem in Gelsemium sempervirens, Ait. 47 
HistoLocy oF A Nopat SEcTION. 
Near a node the circle of wood and external phloem becomes 
elliptical, and the patches of internal phloem lie at the ends 
and sides of the ellipse. The end patches are considerably 
larger than the side ones and are further divided into a central 
and lateral portion, the former for the petiole, the latter to 
remain in the stem. Higher up, the ends of the ellipse curve 
out more and more, and soon separate from the sides to form 
the petiolar bundles. Each bundle is accompanied by a por- 
tion of the internal phloem, so that at first the petiolar bundle 
is composed of external phloem, wood and two small masses 
of internal phloem. Left in the stem are the two long lateral 
curves of wood and external phloem as before. The two 
small groups of internal phloem that remained behind at each 
end now move together to reconstitute the end patches. 
Above the node the wood reunites into a continuous ring, 
while at the next node above, the leaf bundles will be given off 
from the opposite sides of the stem. 
The petiolar bundles are at first distinctly bicollateral. 
Numerous patches of external phloem border upon the outer 
or lower face of the wood, and on its inner or upper face are 
two clearly defined patches of internal phloem. Almost im- 
mediately after the petiole has separated from the stem, the 
main petiolar bundle gives off two small lateral branches. 
These bundles consist chiefly of external phloem with a little 
xylem. They continue upward through the petiole and along 
the sides of the leaf, where their branches anastomose with 
branches from the main leaf bundle. A remarkable change 
soon takes place in the main petiolar bundle of a kind which, 
so far as I am aware, has not previously been described. 
Just above the point where the lateral petiolar bundles branched 
off, the twointernal phloem patches, one after the other, pass down- 
ward and outward through the wood to join the external phloem. 
In a transverse section of a petiole, the phloem strands may be 
seen in longitudinal section passing between the xylem cells. 
