204 
Journal of Agricultural Research 
Vol. XXX, No 3 
of the vascular bundles in the various 
regions of the stem, it seems best to 
take typical bundles, study their struc¬ 
ture and note the changes that take 
place as these bundles pass through the 
nodal and internodal region of the stem. 
The typical bundle, as found in the 
larger part of the cane, except in the 
in relation to each other. The pro- 
toxylem consists of annular and spiral 
elements. Below it is the protoxylem 
lacuna, a lysigenous* cavity into which 
often project the remains of the first- 
formed annular vessels (pi. 3, B). 
Above and lateral to the protoxylem 
are two large vessels with medium long 
cap on the phloem pole. 
peripheral region, is rhomboid in cross 
section. It is surrounded by a well- 
marked sclerenchymatous sheath which 
is most strongly developed on the in¬ 
side and the outside of the bundle where 
it forms typical bundle caps (fig. 3). 
The vascular tissue of the bundle has 
xylem and phloem disposed collaterally 
articulations which communicate by a 
single large pore. The vessels are sur¬ 
rounded by tangentially flattened pa¬ 
renchyma cells (pi. 4, A), which com¬ 
monly possess reticulate thickenings. 
There is profuse pitting between the 
vessels and the parenchyma, but where 
a vessel directly adjoins the sheath 
