374 Cooke and Schively on Observations on the 
olus, and have remains of cytoplasm. They are nearly filled 
with compound starch grains. The central pith cells also 
contain a little starch, but the outer pith cells, near the bun- 
dles, are densely packed with starch deposits. 
HIsToLoGy OF THE MATURE Root. 
The root is very nearly circular in cross-section. There 
is a single epidermal layer of cubical thin-walled cells. These 
walls are thinner than those of the parenchyma cells within, 
and have a brownish-yellow color in the fresh material. 
They contain a brown dense elliptical nucleus lying against 
the inner wall. These epidermal cells never have a flat 
external surface in the fresh state. The external wall either 
bulges outward or is depressed and curves inward. This 
fact, together with the thinness of the walls, seems to indi- 
cate an absorbent function in these cells. 
The parenchyma is of large round thick-walled cells, 
densely filled with starch grains. These cells do not taper 
longitudinally, but flatten against each other. There are 
strong indications of pore connections through their common 
cell walls, and also a very evident lamellation. A large 
nucleus is frequently seen against the glistening yellow cell 
wall, while considerable protoplasm and a nucleolus are 
usually evident. Starch grains are abundant and are mostly 
single or double, the complex forms being rarely found in 
the stem. Some show an irregular, semi-dissolved outline. 
Occasional parenchyma cells show a clear matrix, in which 
lie, in a parallel direction, numerous shining crimson needle- 
crystals. They are slender spindle-shaped forms, with thick 
centre and pointed ends, about one-third the length of the 
cell. Such cells occur in groups of two or three and contain 
no starch. 
There is a small central bundle, not sharply separated 
from the cortex, as an endodermis is absent. Across it 
passes a central band of wood, consisting of a few spiral 
