408 Boodle. — Anatomy of the Schizaeaceae . 
that there is no evidence for the repeated bifurcation of the 
young central cylinder, described by Van Tieghem as 
characteristic of. his polystelic type. The structure of the 
seedling of Anemia bears this out ; the stele as a whole does 
not appear to branch. In Anemia , internal phloem appears, 
when there are only a few soft elements inside the xylem. 
This may mean that a medullated stage was not passed 
through in this particular phylum, or it may be a case of 
the early appearance of an acquired structural character. 
Again, in the seedling solenostelic structure precedes dialy- 
stelic, which may have phylogenetic significance. But these 
facts do not elucidate the morphological difficulties. Neither 
does investigation of the apex greatly help the matter. 
G wynne- Vaughan (’ 97 , p. 323) found in species of Primida , 
with several steles arranged in a slightly interrupted ring, 
that these were represented in the apex by a similar ring 
of desmogen-strands, which could be followed up as far as 
any differentiation could be distinguished in the meristem. 
This practically describes what was found in the apical region 
of an oldish seedling of Anemia Phyllitidis . This was to be 
expected. When differentiation begins in a meristem, the 
form and mode of division of its elements is intimately con- 
nected with the form and arrangement of the tissue-elements 
to be produced, so one is not likely to learn much from these 
characters in the meristem, that cannot be seen in the mature 
structure. The relation of the meristematic tissues to the 
divisions of the segments of the apical cell could not be made 
out. If this could be determined, it would carry some morpho- 
logical weight, especially in nearly allied forms. If, for instance, 
it could be shown that the steles of Anemia Phyllitidis to- 
gether with the central ground-tissue were formed from 
similar divisions of the apical cell-segments to those from 
which the solid stele of Lygodium is formed, a presumption 
of morphological identity would be established. The arrange- 
ment of cell-walls in the apical region of Anemia did not 
suggest what might be called an intrusion of cortex into the 
stelar ring. 
