394 Boodle. — Anatomy of the Schizaeaceae. 
Anemia Dregeana , except for the fact that in the latter 
species the lateral protoxylem-groups are spread out, while 
in Mohria they are small. Fibres are absent in both. 
Mohria, root. 
The root of Mohria caffrorum agrees with that of Anemia 
Phyllitidis in the structure of its cortex, endodermis and 
pericycle, the chief point of difference being in the stele, which 
in the roots examined did not have two specially large 
tracheides in the middle of the metaxylem, but the xylem- 
band showed more gradation from the small elements at 
its ends to the larger tracheides in the middle, which were 
fairly numerous and irregularly placed. This distinction 
is however not very important, as the Mohria type of 
structure is sometimes found in species of certain Polypo- 
diaceae, which usually have two large tracheides in the 
metaxylem, as in Anemia. The root of Mohria resembles 
somewhat the basal region of the root in Anemia. 
Cavity-parenchyma. 
This tissue, which is well developed in Anemia Phyllitidis , 
has been described in that plant by Prantl (’81, p. 24 ). A 
similar tissue was found by Gwynne-Vaughan (’01, p. 87) in 
Loxsoma , and his term (cavity-parenchyma), which is an 
equivalent for Russow’s Liickenparenchym, has been adopted 
here. Reference to other authors who have described a 
similar tissue are given by Prantl and Gwynne-Vaughan. 
It is found in a large number of Ferns belonging to different 
Natural Orders, e. g. besides the two genera just mentioned, 
in Helminthostachys , Matonia , Osmnnda , Angiopieris , Cyathea , 
Pteris. The character of this tissue, as described by different 
authors, lies in the fact that the cells composing it become 
enlarged and produce thylosis-like swellings or branches. 
As mentioned by Gwynne-Vaughan, they grow into the 
space caused by the disintegration of the protoxylem-elements. 
They may perhaps have a mechanical function. In Tricho - 
