376 Chandler.-— On the Arrangement of the Vascular Strands 
Blechnum brasiliense, Desv. 
The ontogeny of the vascular system of this plant so closely resembles 
that of Lomaria Spicant that further description is unnecessary. 
The radiciferous strands described by Trecul 1 and Lachmann 2 3 as 
occurring in this plant were not noticed, probably owing to the examples 
examined being comparatively young. 
Asplenium bulbiferum, Forst. 
In investigating this plant it was intended to compare the transitional 
changes in the seedling with those in the adventitious buds which are 
so common on the mature fronds. Unfortunately, the seedlings could not 
be obtained, and hence the following account is concerned with the adven- 
titious buds alone. It is hoped the seedlings may soon be available 
and the necessary comparison made. 
The buds arise as outgrowths of the leaf-tissue in the immediate 
neighbourhood of the swollen end of a vein supplying the large sorus. 
The suitability of such a point of origin is obvious. The young bud 
possesses a simple concentric vascular strand, connected with the vein 
of the leaf and surrounded by a well-marked endodermis. The strand 
is oval in section, and the xylem, consisting of tracheides and parenchyma 
in about equal proportions, shows no distinct protoxylem elements. The 
phloem completely ensheathes the xylem, and the sieve-tubes are well 
marked. The pericycle and endodermis have their cells in sedation, as 
is the case in so many ferns. The endodermis itself is often two or three 
cells deep locally, and has conspicuous brown cell-walls. 
The ground-parenchyma is quite normal in structure but the more 
external cells are frequently meristematic, their division resulting in the 
formation of radial rows of cells, which, however, soon lose their radial 
arrangement. 
In older stages, the parenchyma of the xylem has taken up a central 
position, and sieve-tubes very quickly appear, frequently as a strand at the 
centre. We thus have the usual amphiphloic structure so general in 
the other cases examined, but in the absence of a primary root, the 
preceding protostelic condition naturally does not occur. 
The first leaf-trace is quite simple, a sector of the vascular ring 
affording the necessary strand. The gap is immediately closed. It is 
interesting to note, in connexion with the later traces, that the xylem 
of the trace as it leaves the cauline strand is somewhat bilobed. 
1 Remarques sur la position des trachees dans les Fougeres. Ann. Sc. Nat., 5 e s^r., xii, 
p. 274. 
3 Contributions, etc., Thesis prdsentee a la Faculte des sciences de Paris, s^r. A, no. 116, 1889. 
