Anatomy of Solenostelic Ferns . 703 
More rarely, it is not the central strand itself that goes to 
fuse with the margin of the lacunae, but a branch given off 
from it ; in which case it terminates there and does not 
separate off again. Even in rhizomes of medium size indica- 
tions of this second internal system are not wanting, for it 
is often to be observed that one of the margins of the lacunae 
in the first internal vascular cylinder is considerably thickened, 
and projects inwards in a manner similar to the margins of 
the leaf-gaps in the solenostele of Dicksonia adiantoides . The 
solenostele at the base of the lateral shoots (which arise from 
about the middle of the back of the petiolar strand, and 
not from its margin) is perfectly typical and without any 
internal strands. I have no doubt that a series of stages 
intermediate between this and the complex structures described 
above are to be found in weak rhizomes, or, at any rate, in 
the young plant. 
Judging from the description given by Seward 1 the vascular 
system of Matonia pectinata seems to be essentially similar 
to that of Pteris elata , both as regards the arrangement of the 
internal accessory strands, and also in their relation to the 
leaf-insertion. Miss Wigglesworth’s 2 account of the same 
plant serves to strengthen this opinion, although it appears 
that in her specimen the complexity of the internal systems 
is carried a step further still. For the third and most central 
system, which in Pteris elata consists of a small rounded 
strand only, is represented by a large gutter-shaped strand, 
or even by a completely closed cylinder. 
From the description of Dicksonia Plumieri ( Saccoloma 
adiantoides , Sw.) given by Mettenius 3 it is clear that in this 
plant again the vascular system is constructed upon exactly 
the same plan, and, moreover, it appears that a still higher 
degree of complexity is reached than in the Matonia of 
1 The Structure and Affinities of Matonia pectinata , Phil. Trans. Roy. Soc., 
Lond., Series B, vol. cxci, p. 171, 1899. 
3 Notes on the rhizome of Matonia pectinata , The New Phytologist, vol. i, no. 
vii, p. 157, 1902. 
3 1. c., p. 531. 
