Obituary. — David Thomas Givynne- Vaughan. xvii 
both being relatively simple forms anatomically. Interesting conclusions 
were drawn regarding the anatomical distinctions between the Marattiales 
and Filicales ; among the characters peculiar to the former group the 
internal protophloem is the most striking. 
Another paper of the same date (1905. %) has a curious title : ‘ On the 
Possible Existence of a Fern Stem having the Form of a Lattice-work Tube ’. 
The epidermal pockets found in the Ostrich Fern and other species are 
compared with the endodermal pockets which started the lattice-work 
structure of the vascular system in so many Ferns. If the epidermal 
pockets likewise became continuous, the whole stem might assume the 
form of a lattice-work tube. Both series of changes are due to the in- 
creasing dominance of the leaf and the leaf-traces. It is an ingenious little 
paper of an unusual kind. 
Leaving the joint series with Kidston for future consideration, we will 
next take Gwynne-Vaughan’s much-disputed work ‘ On the Real Nature of 
the Tracheae in the Ferns 5 (1908). In this paper he endeavoured to show: 
(a) That the pits in the Ferns investigated are open. 
(b) That the middle lamella of the tracheal wall is absorbed, leaving an 
open vertical passage between the bars of thickening. 
The investigation was suggested by the appearances observed in some 
of the fossil Osmundaceae. He summed up his conclusions as follows : 
‘ The xylem elements of the Pteridophyta are, for the most part, vessels with 
true perforations in their longitudinal as well as in their terminal walls.’ 
‘ In the Osmundaceae, N ephrodium Filix-mas , and probably others, 
a special type of vessel occurs which is characterized by the complete 
disappearance of the primary tracheal wall at certain points, so that the 
cavities of the pits are vertically continuous in the middle of the wall.’ 
Gwynne-Vaughan’s results were controverted by Halft in 1910, and by 
Miss N. Bancroft in the following year. Their work leads to the conclusion 
that the old view was right, i. e. that the pits in Pteridophyta are, as a rule, 
closed, and that the middle lamella is persistent. 
Gwynne-Vaughan was in touch with Miss Bancroft’s work, and helped 
her with criticism and advice. 
This is not the place to discuss the question, but I may be permitted 
to quote the following passage from a letter of Mrs. Gwynne-Vaughan’s, 
which defines her husband’s position in the matter : 
‘With regard to the Fern-tracheae I think I can best summarize 
my husband’s view by saying that he thought the question required 
further investigation. I do not think he would ever have undertaken this 
himself ; it did not interest him as much as the other things he had 
worked on.’ 
We have now reached the period of Gwynne-Vaughan’s co-operation 
with Kidston, a most happy conjunction which gave rise to much good 
