the Anatomy of the Genus Selagmella. 453 
two leaves, but he does not figure it. He gives no details of 
the anatomy of the root in any of the species which he dis- 
cusses, but gives a short general summary, which, however, 
adds nothing to what had been previously known. 
In a paper on 5 . lepidophylla, Wojinowic (8) says that there 
are no rhizophores in that species, that the roots arise directly 
from the stem, and without any relation to the branching of 
the axis. The root in this species shows in transverse section 
an epidermis with two or three layers of thin-walled hypo- 
dermis, followed by five or six layers of sclerenchyma, an 
endodermis, peri cycle and normal-monarch vascular strand. 
Bruchmann ( 9 ), in his monograph on 5 . spinosa , adds no new 
points beyond drawing attention to the occurrence of symbiotic 
fungal hyphae in the roots. He adds that this species and 
Lyallii are destitute of root- hairs. 
In passing, it may be pointed out that Bruchmann, in 
describing the curious centroxylic condition of the vascular 
system in the creeping part of the stem, remarks : ‘ wie es 
bisher noch von keinem Stengel der Gattung Selaginella 
bekannt war.’ Bruchmann’s paper was published in 1897, 
but I may perhaps be permitted to point out that I described 
and figured that condition in this species in 1894 (11). 
In the accounts of the root-system in the genus Selaginella 
given in the textbooks, it is customary to distinguish the 
unbranched aerial portion of the root as a ‘ rhizophore,’ and 
to retain the term ‘ root ’ for that part which is underground 
and bears a root-cap and root-hairs. It would seem advisable 
at the outset to determine whether that nomenclature, and 
the views on which it is founded, can be maintained. 
The chief arguments advanced in its favour are those of 
Nageli and Leitgeb, who claim that the aerial part of the 
root is of cauline value on the ground that it has no root-cap, 
that it is occasionally transformed into a leafy branch, and that 
it arises exogenously whilst the true roots are developed 
from it later endogenously. This view is combated by Van 
Tieghem ( 4 ) and Russow ( 5 ). 
In studying the comparative morphology of the root it is 
I i % 
