in the ‘ Seedlings * of Certain Leptosporangiate Ferns . 393 
the case of N ephr odium setigerum , all the plants examined showing the 
roots to be more numerous, and somewhat irregularly arranged. 
The first few leaf-traces are formed in a manner similar to that 
described above, the closing of the gaps resulting in the formation of a ring 
of xylem surrounded by phloem, and containing a phloem pith in which 
isolated tracheides occasionally occur. After about the fifth or sixth trace, 
a portion of the xylem ring becomes reduced in thickness to only two or 
three rows of tracheides, the attenuated arc bulging slightly outwards. At 
a higher level, this arc of vascular tissue passes out as a leaf-trace, but 
before the xylem has broken away from the cauline strand we have the 
formation of so typical a fundamental-tissue pocket that no further descrip- 
tion is necessary. A transverse section of the stem through the region 
of the pocket is shown in Fig. 203. The leaf-trace presents a distinctly 
bilobed appearance, especially with regard to its xylem, and, as might be 
expected, this is an indication of the later formation of multiple leaf- 
strands. Before the gap closes, the cauline strand becomes strongly 
curved, the middle portion of the arc being thinner than the extremities, 
and quickly passing out as a leaf-trace which is still more markedly bilobed 
than its predecessor. 
The subsequent closing of the previous gap is followed by a re- 
splitting of the strand into two unequal parts. The next leaf-trace is 
joined to the margin of this split, and is double from its origin. The 
subsequent elaboration of the vascular system results in the formation 
of the usual dictyostelic structure, and need be described at no further 
length. 
The young plants of Nephrodium setigerum would be described as 
* soft ’ plants by the cultivator, sclerenchyma being absent in the ground- 
tissue, a state of affairs very different from that obtaining in other ferns, 
e. g. Pteris palmata . The endodermis is well marked, but its cells are by 
no means in perfect seriation with those of the pericycle, which generally 
consists of but one layer of cells without the very abundant contents which 
so often characterize this layer. The vascular-tissue elements call for no 
special description except that the small sieve-tubes are well differentiated, 
and that the xylem contains a considerable amount of parenchyma, which 
frequently occurs as plates of cells in connexion with thd^phloem. 
Nephrodium hirtipes, Hk. 
The early transitional changes of N ephrodium hirtipes proved to be of 
quite an interesting character. Unfortunately, the writer was unable to 
verify his results in more than the five plants at his disposal, but the 
essential uniformity of the few examples investigated affords good reason 
for supposing that the phenomena observed are those obtaining generally 
in the plant. 
