Bower. — Studies in the Phytogeny of the Filicales . 373 
as a rule, but it is variable. The basipetal sequence is not long maintained, 
nor is it very marked even in favourable cases (Fig. 3, e,f). Later on there 
may be a transition to a mixed condition of the sorus, by interpolation 
of younger sporangia between those already formed (Fig. $,g) ; this is the 
usual state in strongly developed pinnae. 
Commonly, a vascular commissure appears, as already noted, which 
runs parallel with the midrib, and connects the successive veins one with 
another, so that in each transverse section a vascular tract will be present 
below the sorus (Fig. $,fg). But exceptions occur where the commissural 
development is incomplete, a condition shown in Fig. 3, A, where no vascular 
tissue nor any sorus is seen. This interruption of the sorus and commissure, 
going along with the prevalent basipetal condition of the sorus, is believed 
to indicate a relation of B. discolor to primitive types, such as Matteuccia , 
in which these two characters are constant. The similarity of the leaf- 
trace to that of Matteuccia , already noted, points in the same direction. 
Nevertheless, the usual condition in well-developed fertile pinnae of 
B. discolor appears to be the more advanced one, with continuous vascular 
commissures, and with sporangia of ages more or less mixed, borne in 
a continuous band above it, and not located in circumscribed sori, as in 
Matteuccia. 
The dermal appendages in B. discolor are chiefly brown scales on the 
axis and leaf-bases ; scales of smaller size extend up the leaf, and cover 
the young pinnae. But here there are present also numerous glandular 
mucilaginous hairs of the usual Blechnum type. 
(B) Blechnum tabulare (Thunb.), Kuhn. 
This subdendroid species, frequently known under its synonym of 
Lomaria Boryana (Swartz), Willd., was obtained in Jamaica, and large 
plants from that source living in the Glasgow Garden have provided 
developmental material. It spreads from the West Indies to the Falkland 
Islands, and is found in South Africa. In characters it is near to B. capense 
(L.), Schlecht ( = Lomaria procera :), but it differs markedly in texture, and 
in the black, narrow scales on its stem and leaf-bases. It is a dwarf Tree- 
Fern. Sir W. Hooker (Sp. Fil., vol. iii, p. 27) gives the height of the stem 
as 1-2 feet, but Gardner (MS.) quotes it as 4 feet high near to the summit 
of the Organ Mountains. 
The vascular system ol a large axis has been examined, and it was 
found to show characters which are usual for the Blechnoid types (Text- 
fig. 3). It is dictyostelic, with a massive pith. In the drawing the foliar 
gaps of the leaves are numbered in succession according to the level at 
which the gaps were traversed in the section, 1 being cut nearest to the 
base of the gap which it traverses. Following this series a clear idea of 
the vascular system will be obtained. Number 1, being cut just where 
