366 KANSAS UNIVERSITY SCIENCE BULLETIN. 
width from 12 to 18 microns. The parenchyma cells of the 
pericycle are similar in form and structure to those of the pri- 
mary cortex. For the most part they contain starch, but in a 
few may be found chloroplasts, and in many crystals of cal-— 
cium oxalate. In the palisade and all of the parenchyma cells 
of both primary cortex and pericycle there are large quantities 
of tannin, and all have a brownish-red color. 
The narrow vascular bundles are collateral, and are sep- 
arated by narrow medullary rays, one ce}l in width. 
The phloém is composed of undivided mother cells of sieve 
tubes and companion cells and thin-walled parenchyma, inter- 
spersed with comparatively thick-walled, lignified bast fibers 
(fig. 10, plate III). The bast fibers are similar in structure 
and arrangement to those of the pericycle, but a greater pro- 
portion of them occur singly, and the groups are smaller. The 
vertically elongated parenchyma cells contain starch, amor- 
phous proteids, and crystals of calcium oxalate (fig. 11, plate 
III). Sieve tubes with well-developed sieve plates were not 
found, but the stems are well supplied with undivided mother 
cells, which are filled with granular proteid matter, and to- 
gether with the parenchyma contain tannin in considerable 
quantities (n, fig. 11, plate III).. 
The elements making up the xylem are fiber tracheids, water 
tubes, and few wood parenchyma cells. The most conspicuous 
_of these is furnished by the fiber tracheids, which are thick- 
walled, strongly lignified and compactly arranged, thus leaving 
very small intercellular spaces. They are cylindrical, and have 
long, tapering ends, which overlap and are interwoven to make 
the wood exceedingly strong (fig. 12, plate III). They vary in 
length from 350 to 1100 microns and 10 to 14 microns in 
width. Although the thick-walled tracheids are perforated by 
numerous bordered pores, and are thus well adapted for water 
conduction, the numerous water tubes are apparently suffi- 
cient to perform that function and leave the tracheids to serve 
rather the function of water storage. (See fig. 8, plate III.) 
In a stem 4.21 mm. in diameter, the tracheids comprise an 
area of 5.9 sq. mm., which is equal to 78 per cent of the xylem 
or 19.7 per cent of the whole stem. The small cavities of the 
tracheids have a total area of 0.7 sq. mm., which is equal to 
8.75 per cent of the xylem or 3.5 per cent of the whole stem. 
The tracheal elements are composed of water tubes having 
spiral and reticulate thickenings and those having bordered 
