390 SECTIONAL TRANSACTIONS.— K. 



are due to the influence of environment (biological characters) and those 

 which remain unaffected by variations in conditions of growth (inherent 

 characters). Certain of the anatomical characters of wood are eminently 

 susceptible to climatic and edaphic influences. Intensive research in wood 

 anatomy is required to formulate correlations between silvicultural factors 

 and the technical properties of timber, and to establish the systematic 

 anatomy of wood on a sound basis. A recently formed organisation 

 designed to advance the study of wood anatomy by international co-opera- 

 tion between interested persons and institutions is outlined. 



Tuesday, September 6. 



Dr. H. Bancroft. — A contribution to the geological history of the Diptero- 

 carpacece. 



A collection of fossil dicotyledonous woods from the slopes of Mount 

 Elgon, an extinct volcano on the borders of Kenya and Uganda, contains a 

 considerable proportion of specimens showing typically dipterocarpaceous 

 structure, the outstanding features of which are secretory canals and 

 heterogeneous, uni-, bi- and narrowly multiseriate rays. 



The Dipterocarpaceae are represented in Africa at the present day only 

 by Monotes and Marquesia, two genera in which the wood-structure is 

 divergent from that typically associated with the Dipterocarpaceae, having 

 (in the material so far examined) no secretory canals, and uniseriate rays 

 only. 



The Elgon fossils, which are apparently of late Tertiary age, are therefore 

 of interest, as indicating a former distribution of the true dipterocarpaceous 

 type, more extended than at the present time. 



Prof. H. S. HoLDEN. — A fossil plant of doubtful affinities from Autiin. 



The material of the plant described consists of small linear-lanceolate 

 leaves with recurved margins, these being traversed by an unbranched 

 tangentially flattened midrib composed of spiral tracheids. The stomata 

 flank the midrib and are confined to the lower side. The leaves are believed 

 to have a petiole with a monodesmic trace, circular in transverse section, 

 the xylem of which consists wholly of spiral tracheids. The name Bertrandia 

 autunensis is suggested as appropriate. 



Dr. H. DuERDEN. — Tracheidal variation in ferns. 



An examination of the xylem elements of certain fossil and living ferns 

 shows that the pit-closing membrane is present between the pits on all 

 the walls in Metaclepsydropsis duplex, Diplolabis Romeri and Botryopteris 

 cylindrica. In Stauropteris burntislandica the membrane is absent between 

 the pits on all the walls, whilst in Pteridium aquilinum it is absent from the 

 pits on the oblique end-walls only. In Osmunda regalis, O. cinnamomea 

 and Todea barbara the membrane is present between the pits on some 

 of the walls, but the pits on many of the walls are true perforations, the 

 closing membrane having disappeared. 



Miss M. G. AsHTON. — The development, morphology and anatomy of the 

 winter bud of Glaux maritima L. 



GLaux maritima L. perennates by a winter bud fixed by long storage 

 roots, and arising as an axis of the second or third order. Such buds arise 

 on non-flowering plants and seedlings, in the axils of lower leaves and 



