Bower.— Studies in the Phytogeny of the Fi tic ales. 375 
or base, where the flap may be in varying degree progressively intra- 
marginal. Such data are important as giving the opportunity of seeing the 
very first steps in origin of that assimilating flange which becomes so promi- 
nent a feature in the Eu-Blechnum section of the genus. Moreover, they 
provide an interesting comparison with the very similar condition in B. discolor . 
Another important question in this species is the order of appearance 
of the sporangia. There is a considerable constancy in the basipetal 
sequence, though the number of sporangia in each section may be small 
(Fig. 4 ,g). For instance, three whole slides of sections were looked over 
without a single departure from it being seen. But exceptions are occa- 
sionally found, and one is shown in Fig. 4, h. 
(C) Blechnum lanceolatum (R. Br.), Sturm. 
This is again a species with a relatively simple structure of its fertile 
pinna, which shows no marked flange, or only one which is variable, owing 
to enlargements of the tissues of the wings rather than to any definite 
tissue formation. It is ranked with the ‘ spicant * group by Hooker, but it 
has a more simple form than most of the species of that affinity. The out- 
line and venation of the fertile pinna are shown in Fig. 5. The plant has 
a short ascending stock and a terminal tuft of strongly dimorphic leaves. 
A supply of material was sent to me by Mr. C. E. Foweraker, Waimate, 
S. Cant., New Zealand, to whom my best thanks are due. 
Transverse sections of a fairly advanced pinna, taken at such a point 
as x-y in Fig. 5, show an outline as in Fig. 6, a. The contour of the section 
is almost circular, owing partly to the curvature of the regions right and 
left of the midrib, partly to the great distension of the tissues below the 
receptacles, which appear as assimilating tissues with stomata. The margins 
appear directly continuous into the ‘ indusial ’ flaps, which are curved over 
to protect the sori. There are sometimes two, sometimes only one vascular 
strand in the midrib, while beneath each sorus is a longitudinal commissure 
connected with the midrib by oblique veins. A vascular supply also 
branches off towards the upper surface of the pinna, each twig of which 
terminates in a gland, as is seen in some other species. The relation of this 
to the receptacle is shown in Fig. 6, b. The sorus is continuous, as in other 
species. The sporangia are spread over a rather wide flattened surface, and 
arise almost simultaneously ; but, as development shows, there are indications 
of a basipetal succession, while later there may be seen some slight mixture 
of various ages together. 
A transverse section of a young fertile pinna shows a segmentation as 
in Fig. 6, d. It is here obvious that the lateral flap results from the usual 
marginal segmentation, and the marginal cell itself is seen rather strongly 
deflected towards the lower surface. The deep cells which intervene between 
it and the midrib give rise to the sporangia, while the indusial flap which 
