in the ‘ Seedlings ' of Certain Leptosporangiate Ferns . 385 
established, and Polypodium aureum is brought into line with the normal 
type. 
The early stages of Polypodium aureum find an almost exact parallel 
in the young seedlings of Ceratopteris thalictroides. Miss Ford 1 has given 
an account of the transitional changes occurring in this interesting fern, and 
describes the gradual change of the root-strand into a normal protostele, 
and the subsequent exit of a few simple leaf-traces. Soon, however, the 
cauline strand apparently breaks into two, just as in the case described 
above. Unfortunately, Miss Ford was unable to follow out the later 
changes, and infers that in Ceratopteris we have evidence of a kind which 
lends support to the essential idea of Van Tieghem’s theory, viz., the 
branching of the original single cauline strand, the protostele. With this 
inference the present writer is inclined to disagree. It is probable that if 
older stages had been examined, the breaking of the stem strand would 
have been found to have been in intimate association with the formation of 
a leaf-gap, a view supported by the evidence of Polypodium aureum , and 
by the text figure of Miss Ford’s paper (p. 106), which clearly shows the 
bundle system of Ceratopteris to be a vascular tube interrupted by elongated 
and exaggerated leaf-gaps. 
The occurrence of similar early transitional changes in the two plants 
is of some interest, since it supports the conclusion arrived at by Miss Ford 
with regard to the systematic position of Ceratopteris , viz., that the plant 
finds its nearest relations among Polypodiaceae. 
Since the publication of a preliminary note 2 on the present work, 
the writer has received a communication from Miss Ford confirming the 
account given above of the early transitional stages of Polypodium aureum. 
Miss Ford further observed a few variations from the normal type, most 
of which were also noted by the writer. 
Nothochlaena sinuata, Kaulf. 
The transitional changes occurring in this plant proved to be of 
a most interesting type. The primary root is diarch, but the vascular 
elements are somewhat irregularly arranged and by no means well differen- 
tiated, the latter being especially the case with the sieve-tubes. Considerable 
variation occurs in the earliest transitional changes, but generally the 
xylem plate becomes more or less circular in transverse section, and, as 
usual, a small strand of parenchyma is differentiated at its centre. It 
is extremely difficult to say whether sieve-tubes occur among the paren- 
chyma cells ; some of the latter are smaller than their neighbours, and 
1 The anatomy of Ceratopteris thalictroides , L. Annals of Botany, xvi. 
2 New Phytologist, May 1904. 
