30 fackson . — Anatomical Structure of the Roots of Barley . 
walls, and among these occur typical spiral and scalariform vessels. This 
layer of cells is bounded by the thin-walled elements of the pericycle and 
endodermis, and outside these are the parenchymatous cells of the cortex 
and of the piliferousiayer. 
Incipient laterals are present in a typically ‘ unbranched ’ root. This 
is shown in Fig. 9, where the continuity of both the pericycle and the 
endodermis is entirely broken by a group of meristematic cells in process 
of forming a lateral branch. This condition is of frequent occurrence and 
shows up very clearly, as the meristematic cells readily take up the stain. 
piliferous layer. 
cortex. 
meristematic cells of 
undeveloped lateral [ 
xy/em vessel 
*part of a TS.of an “Un branched "foot, 
showing an undeveloped lateral, fx no} 
Fig. 9. 
It closely resembles the appearance depicted by Nageli and Leitgeb 1 for 
the development of lateral roots in Oryza. These incipient roots remain 
dormant in their meristematic condition for some time, and only push out 
when the root is changing from the ‘ unbranched ’ to the branched type. 
The 4 unbranched 5 roots from the grain are also adventitious, and on 
sectioning them it is found that their structure is strictly comparable 
with that of the 4 unbranched ’ roots from the node, a typical section 
showing a stele with characteristic parenchymatous central region and 
three ducts. 
1 Nageli, C., and Leitgeb, H. : loc. cit. 
