Boodle . — Anatomy of the Schizaeaceae. 409 
An important method of investigation is a comparison of 
the structure in nearly allied species. A thorough examina- 
tion of several species of Anemia would be most interesting 
from this point of view, but sufficient material has so far 
not been obtainable. One or two points that have some 
bearing on the endodermis and stele, however, must be men- 
tioned. A. mexicana is solenostelic with a central mass of 
sclerotic tissue inside the inner endodermis. This is homo- 
logous with the central ground-tissue of Anemia Phyllitidis. 
Such tissue may become sclerotic in polystelic forms, as seen 
in Mokria. The formation of abundant sclerotic tissue is 
rather a character of xerophytic forms, and its function, 
besides being mechanical, is possibly connected with the 
storage of water in its walls and cavities. A. mexicana is dis- 
tinctly xerophytic in appearance, which would be expected, 
as it is described as growing on rocks. In this species at the 
node a group of sclerotic tissue appears to become detached 
from the central sclerotic ground-tissue and to pass out behind 
the leaf-trace so as to join the external sclerotic ground-tissue, 
as in Mohria; there is thus a leaf-gap in the endodermis. In 
the node of A. coriacea, which is probably nearly related to 
A. mexicana , no sclerotic tissue passes out, and the endodermis 
is not interrupted, hence, judged by the node examined, this 
species is not properly solenostelic. If this character were 
constant for all the nodes of A. coriacea, its central ground- 
tissue, judged by continuity, would have a totally different 
morphological nature from that in A. mexicana ; which is 
extremely improbable. This matter must be left for future 
investigation, but it may be pointed out, that from the 
physiological point of view the connexion at the nodes 
between the inner and outer ground-tissue, when they become 
sclerotic, is comparatively unimportant, except perhaps that 
an occasional connexion might be necessary, either as a tie 
between two mechanical systems, or for the slow transference 
of water from one to the other. 
Another point suggested by these species is that, assuming 
them to have been derived from polystichous forms by 
