XV 
Obituary.— David Thomas Gwynne- Vaughan. 
The second part of the Solenostelic work, which appeared two years 
later (1903), had a much wider scope, and extended to Ferns of other than 
solenostelic structure. It is, in fact, one of the chief existing contributions 
to Filicinean anatomy. 
Gwynne-Vaughan showed that the dictyostely (typical polystely or 
dialystely of Van Tieghem), so common in Ferns, is ‘ primarily due simply 
and solely to the overlapping of the leaf-gaps in a solenostele ’, though 
other gaps in the tube may occur, as in Dicksonia rubiginosa . He traced 
the origin from the solenostele of internal vascular strands, and of internal 
tubes, such as were found by him in Pteris elata , and were previously known- 
in Matonia . 
Incidentally he called attention to a curious historical point. c Having 
first come to the conclusion that Ferns do not possess true seeds, Cesalpino 
proceeded to deduce the fact that they cannot possess true stems either.’ 
This, then, was the strange origin of the belief, so obstinately main- 
tained, even down to our own times, that the ‘ caudex ’ of a Fern is merely 
a sympodium of leaf-traces. It also became the source of the f phyton ’ 
theories of Gaudichand and others. Gwynne-Vaughan showed that the 
apparent segmentation of certain Ferns is really to be regarded as a late 
development rather than as a primitive feature. In connexion with this 
question he investigated the course of the internal strands of Cyatheaceae 
and other Ferns, and found, in agreement with Trecul, that they are not 
decurrent leaf-traces, but strictly and essentially cauline. 
He thoroughly worked out the development of the dictyostele in the 
young plant of Alsophila excelsa , and showed that after the protostelic 
stage a core of phloem first appears, then the internal pericycle, next the 
endodermis, and finally the central ground tissue, the structure thus 
becoming a solenostele. The leaf-gaps as they begin to overlap convert 
this into a dictyostele, and ultimately the complexity of the mature 
structure is attained by the nipping off of the internal strands from the 
main vascular tube. 
When lateral shoots are developed they repeat, more or less imperfectly, 
the ontogeny of the plant as a whole. 
The paper, in which I have only indicated a few characteristic points, 
concluded with a theoretical discussion of the theory of the stele. Gwynne- 
Vaughan strongly inclined to the view that the origin of the central 
parenchyma in the higher . Ferns was to be regarded as stelar, though he 
admitted that Jeffrey’s opinion, that it arose from the cortex, was theoreti- 
cally possible. 
The diagrams of the stelar structure in the solid are an excellent 
feature of the plates, and so are the combined photographs and drawings, 
an under-exposed print being used as a earner a-lucida sketch. 
The paper is altogether an admirable type of modern anatomical work, 
