Psaronius. 
by the ground-tissue of the stem from which it is sharply delimited, 
a relation between root and stem in marked contrast to that 
between the roots and the filling tissue in the extra-cortical region. 
The conclusions reached may be summarised as follows :— 
The Psaronim stem has a thin cortex hounded by a fairly thick 
hypodermal hand of mechanical tissue. This cortical region is 
penetrated by adventitious roots which arise in the internal tissues 
of the stem. Hair-like outgrowths composed of cell-rows are 
developed from the epidermis of the stem and these eventually form 
I 
O 
Psaronius sp. Transverse section of part of the root—enclosing 
parenchyma. I, O, inner and outer side of the section ; a, concrescence of 
filling-tissue with the sclerenchyma of a root. (From Solms-Laubach’s 
specimen in the Rio Janeiro Museum, Coll. Solms, No. 592). 
part of the root-enclosing parenchyma. The roots after emerging 
from the cortex pursue a downward course along the stem surface; 
they grow between the hairs of the filling-tissue and their inner 
flanks become concrescent with the outgrowing hairy tissue 
