370 KANSAS UNIVERSITY SCIENCE BULLETIN. 
tire leaf, is the palisade tissue, usually consisting of a single 
layer of cells (fig. 38, plate VII). The cells well supplied with 
chloroplasts are cylindrical in tangential section, and lie rela- 
tively close together (fig. 41, plate VIII). The rest of the 
mesophyll is made up of parenchyma cells, which, lying close 
together, thus give but little intercellular space in the leaves 
(fig. 38, plate VII). No regularly arranged border paren- 
chyma surrounds the vascular bundles. 
The very conspicuous water-carrying system is composed 
entirely of tracheids, which for the most part have bordered 
pores (fig. 28, plate V); but in the basal portion of the mid- 
vein spiral tracheids may be found (fig. 46, plate VIII). The 
ultimate ends of the veins are composed of large groups of 
nearly isodiametric tracheids with numerous bordered pores 
(fig. 27, plate V, and figs. 44 and 45, plate VIII). The enor- 
mous number of tracheids furnish adequate capacity for the 
storage of a large water supply in the leaf. Interspersed with 
the tracheids are many thin-walled parenchyma cells (fig. 28, 
plate V, and fig. 43, plate VIII). 
The phloém consists of undivided mother cells, cambiform 
cells, and parenchyma (fig. 29, plate V). All of these cells 
have walls of cellulose and are filled with granular proteid 
matter. The phloém occupies but a relatively small portion of 
the bundles, and in no case were well-formed sieve tubes found. 
THE CHLOROPLASTS. 
Chloroplasts are present in both leaves and stems. In leaves 
they occur in the epidermis, palisade, and nearly all of the 
parenchyma of the mesophyll, while in stems they occur in the 
epidermis, palisade and greater part of the primary cortex, 
and even in the outer part of the pericycle. Numerically they 
are about equally distributed in the corresponding tissues of 
stem and leaf, an average of 128 being present in a leaf pali- 
sade cell and about 50 in a parenchyma cell of the stem. In 
form they are circular and biconvex, varying from 4 to 5 
microns in diameter and 1.25 to 1.75 microns in thickness. 
STARCH. 
Both stems and roots are provided with an abundant supply 
of starch. The spherical, oblong or ovoid grains are simple, 
or 2, 3, 4 and 5 compound. In the stem they are located prin- 
cipally in the pericycle, medullary rays, and medulla, but they 
