3 ^ 
Notes on Recent Literature. 
(produced from the stem) which abuts on them. This union of two 
distinct tissues is a feature difficult to understand. As the growth 
of the stem proceeds, additional roots are developed and these grow 
over the older roots. The latter have meanwhile produced outward 
extensions of their cortex differing only in their root-origin from 
those previously developed from the surface of the stem, and this 
tissue becomes intimately connected with the inner flanks of the 
later-formed roots. The parenchymatous tissue external to the 
original stem is thus formed in part by the outward extension of 
the stem cortex and in part by the development of the same type 
of tissue from the cortex of the roots. Instead of root hairs of the 
ordinary type, the roots of Psaronius produced multicellular out¬ 
growths in which they became enveloped as in a cortex, a phenom¬ 
enon to which living ferns have so far afforded no parallel. 
In addition to the new evidence obtained in regard to the 
nature of the extra-stelar tissues of Psaronius, Count Solms deals 
also with some other questions of morphological interest. One of 
these is the supposed secondary thickening described in 1899 by 
Butterworth 1 in the root of Psaronius Cromptonensis. A brief 
description is given of a root of P. Weberi from Chemnitz in which 
a fan-shaped group of tracheae is attached to the end of one of the 
stelar arms. These divergent series of xylem elements are considered 
to be connected with the origin of a lateral root and to correspond 
with the “pedicule” of van Teighem. In other roots examined 
similar supernumerary groups of tracheae were noticed in contact 
with more than one arm of the stele. It is suggested that the 
supposed secondary xylem of Butterworth may consist of several 
such groups, and if this is the case, it means that in P. Crompto¬ 
nensis all the xylem arms of the root were implicated in the origin 
of the vascular supply of a lateral root. Incidentally it is pointee 
out that in Angiopteris several xylem strands of a root stele ard 
concerned in the production of the xylem of a lateral root, whereas 
in recent ferns generally, only one arm of the xylem is affected by 
the development of a lateral root, a fact of some importance in 
regard to the systematic position of the Palaeozoic genus. 
Though there is little doubt as to a close affinity between 
Psaronius and recent Marattiaceae, the work of Count Solms may be 
considered to lend support to the retention of the family-name 
Psaronieae, instead of the inclusion of the genus in Marattiaceae. 
In the current number of the Berichte 2 of the German 
Botanical Society, Julius Schuster publishes a note, with illustra¬ 
tions, on a fern-stem recently described by Professor Pohlig as 
Xylopsaronius Cottai (Corda). This generic name was given by 
Pohlig to Corda’s Permian species from Hilbersdorf, near 
Chemnitz, on the ground that the stem possessed secondary wood. 
An examination of sections cut from the original block demon¬ 
strated that the supposed secondary xylem consists of regular 
series of parenchymatous cells extending in a radial direction 
between the numerous adventitious roots, and affords a typical 
1 Manchester Lit. Phil. Soc., Mem. & Proc., 1898 99, Vol. 43, 1900. 
3 Xylopsaronius ., . der erste Farn mit sekundarem Holz ? Berichte 
der deutsclien Botanischen Geselleschu/t, Bd. XXIX, Heft 8, p. 
545, 1911. 
