Notes on Recent Literature. 
3 ° 
Strands in Angiopteris evecta, and some other Marattiaceae,” 1 
recognise the difficulty of accepting Stenzel’s explanation of the 
nature of the root-bearing region and draw attention to certain 
important differences between Psaronius stems and those of recent 
Marattiaceae. The root in the Marattiaceous cortex, as these 
authors point out, “ is obviously an intrusive organ. But in 
Psaronius, in the best preserved sections that we have seen, the 
outer cortex surrounding the zone of small-celled sclerenchyma, 
and forming a peripheral ring in the roots, passes almost insensibly 
into the parenchymatous tissue between them. Furthermore, the 
cells of the latter are very irregular in character, often producing 
the effect of elongated cells ‘ combed ’ in various directions.” 2 
Count Solms discusses with his usual thoroughness the nature of 
the root-zone, and as the result of an examination of several species 
of Psaronius he adduces important evidence confirming the doubts 
expressed by Farmer and Hill. The roots which lie clear of the 
stem occasionally show distinct indications of cell-division and 
growth in their cortical tissue. This is clearly demonstrated by a 
transverse section of a root figured by Solms in which the cortex 
has a very irregular contour and on one side has grown out into 
a projecting wing of parenchyma consisting of radially disposed 
rows of cells. The inner roots are embedded in parenchymatous 
tissue which Stenzel speaks of as stem cortex, and Solms, adopting 
Rudolph’s term, designates filling tissue (Fiillgewebe). This tissue 
consists of rows of elongated cells radiating outwards from the edge 
of the stem cortex: these rows are usually in contact with the 
sclerenchymatous margin of the slightly flattened roots, while at 
the narrower edges of the roots the rows of elongated cells pass 
directly into the sclerenchymatous cortex with which they are in 
organic connection. This radially extended tissue forms longer or 
shorter tongue-like layers of cells which have been developed by 
the growth and elongation of the outer cortex of the roots. In the 
accompanying figure reproduced from the paper by Solms, I and O 
denote respectively the inner and outer part of the stem in their 
relation to the roots. The relation between roots and enclosing 
parenchyma is strikingly different from that between the roots of 
Marattiaceae and the cortex penetrated by them : in the latter each 
root is surrounded by crushed cells of the stem cortex. In the 
Psaronius roots, on the other hand, the parenchyma owes its origin 
to the outgrowth of groups of filamentous hairs which eventually 
form a continuous mass of parenchyma. When the filling-tissue 
abuts on the side of a root facing the centre of the stem (a, in the 
figure) its cells curve right and left and apply themselves to the 
outside of the sclerenchymatous zone. It would seem, therefore, 
that on the side near the centre of the stem this parenchymatous 
tissue becomes concrescent with the root cortex, while on the 
opposite side there was an active growth and prolongation of the 
superficial cells of the root cortex. 
It is difficult as a rule to recognise the original stem cortex to 
which the proximal ends of the roots were attached, but Solms 
figures a portion of a transverse section of a root surrounded 
1 Annals of Botany, vol. XVI, p. 371, 1902. 
2 Ibid, p. 382. 
