Notes. 
369 
normal phloem there is a band of large parenchymatous cells with 
dense contents and large interspaces. Sometimes strands of sclerotic 
cells and fibres occur here. 
The phloem of the bundle-ring consists chiefly of parenchymatous 
cells densely packed with starch and masses of brown crystalline 
substance, the latter being aggregated chiefly in, or near, the cambial 
region. 
Large rectangular secretory sacs are distributed irregularly through 
the cortex and bast region of the bundle-ring, but are absent from the 
cortical bundles. The tissues of the normal phloem are much more 
loosely packed than those of the cortical bundle : while there are few 
interspaces in the latter, they are numerous and large in the former 
and are even found close to the cambium. 
Tangential sections through the phloem-portion of the cortical 
bundle just centrally to the reversed xylem (along the line ab) show 
on either side : — • 
(1) The one-sided sclerotic cells above mentioned (sJi). 
(2) Within these, also on both sides, are one of four rows of 
parenchymatous cells ( p 2 ) not unlike those of the cortex, and with 
dense starchy contents. 
(3) The whole of the remaining space is occupied by large sieve- 
tubes and their companion-cells together with a few cambiform 
elements. As a rule, from sixteen to thirty sieve-tubes may be 
counted here. They are also found in the recesses (r) on either 
side of the xylem. The companion-cells are short, but very clear, 
and with evident nuclei. The sieve-plates are very prominent even 
in unstained sections ; they are mostly transverse, but some are 
oblique and others nearly vertical. All of them are simple, and no 
cross-connexions were seen here. When a corresponding tangential 
section passing through the phloem-ring of the central cylinder is 
compared with the above, it is seen that the sieve-tubes are very few 
in number : sometimes parenchyma only can be seen. In other parts 
from one to four sieve-tubes occur close together. Their course is 
strikingly irregular, and in many places it can be seen that the 
segments belong to originally separate rows of cells, union being 
effected by a mutual curving of the cells to one another. 
Unlike the phloem of the cortical bundles there are numerous cross- 
connexions very often quite short, but even then showing companion- 
cells. The sieve-plates are inclined in all directions, very few being 
