1 6 Tans ley and Chick . — Notes on the 
thinner and less lignified walls. On transverse section these 
cells usually show no sharp line of separation from those of 
the hypodermal strand, and form together with it a wedge- 
shaped mass of tissue gradually narrowing inwards which we 
propose to call the radial strand. In radial section its inner 
cells are shorter than those of the hypodermal bundle, and 
have horizontal end-walls. They often contain starch. 
At the inner limit of the cortex comes the layer of strikingly 
large, radially elongated cells {end., PI. I, Figs. 12, 15; PI. 
II, Figs. 16-18) described by Haberlandt and Bastit. Their 
radial diameter is often nearly twice as great as the tangential. 
A striking point has been missed by previous observers in the 
thickening and suberization of their radial and horizontal 
walls. This layer in fact presents all the characters of a 
typical root-endodermis. The thickened walls show the dis- 
tinctive reactions, giving good differential staining with the 
aniline dyes (e. g. eosin and iodine green, or haematoxylin 
and safranin), and staining strongly with alcoholic solution of 
chlorophyll and alkannin. 
The endodermis consists of three arcs, each occupying 
a side of the triangular rhizome. The ends of each are curved 
slightly inwards, and abut on the inner, larger cells of the 
radial strand by which the adjacent arcs are separated. 
Central Cylinder. This consists of an inner compact mass 
of tissue with three broad projecting regions, the outer 
boundaries of which are parallel with the three sides of the 
rhizome, and three narrower furrows opposite its angles. 
This central mass consists mainly of very thick-walled 
elongated living cells, often with oblique end-walls, and con- 
taining here and there a little starch. Scattered among these 
stereids are elements of about the same diameter, but so far 
as we have seen quite destitute of contents. These are often 
united, as it appears on transverse section, in bands of two or 
three, the cells of each band being separated by extremely 
delicate cellulose walls, which are really, as Haberlandt has 
shown, the very oblique end-walls of the cells. The walls 
abutting on the stereids are also thin and unlignified. For 
