854 REPORT — 1901. 



WEDNESDAY, SEPTEMBER 18. 

 The following Papers were read : — 



1 . Cuticular Structure of Euphorbia Abdelkuri. 

 By Professor I. Bayley Balfour, F.Ji.S. 



Euj)/iorbia Abdelkuri is an interesting- succulent plant which has been brought 

 home from a small island in the vicinity of Sokotra by the Ogilvie-Forbes 

 Expedition. The outer surface of the plant in the fresh condition appears to be 

 covered with a crust which readily cracks oif. and on examination this is found to 

 consist of a number of prisms. At first sight these may be taken for some form of 

 mineral incrustation, but they are not of this nature, but are formed by the cuticle 

 of the epidermal cells. This does not form an uninterrupted layer over the 

 epidermis, but the cuticle of each cell is separable from that of the adjacent ones, 

 and the prisms are merely blocks of cuticle, each one belonging to a single cell. 

 This is a construction difierent from that which is ordinarily met with in plants 

 with thick cuticular layer. 



2. Some Observations itpon the Vascular Anatomy oj the Cyatheacece. 

 By J). T. Gwynne-Vaughan. 



In a number of Diclssonias with creeping or prostrate stems it is shown that 

 the vascular system is solenostelic, tlie leaf-traces departing as a single strand 

 curved into the form of a horseshoe, with its concavity facing towards the median 

 line of the rhizome — Dicksonia adiantoides, cicutaria, davallioides, apiifolia, and 

 jmnctiloba. 



In I), apiifolia it is found that along the free margin of the leaf-gap there is a 

 considerable increase in the amount of xylem in the solenostele, causing it to 

 project somewhat towards the centre of the stem. 



A similar marginal enlargement also occurs in D. adiantoides ; and here it is 

 continued past the leaf-gap, foi'ming a ridge on the internal surface of the soleno- 

 stele runnino- from one leaf-gap margin to another. In the internode this pro- 

 jectino- portion of the xylem becomes separated off from the rest and surrounded 

 "by a phloem of its own ; however, it remains always included within the same 

 endodermis. 



In Dicksonia rtd)iginosa the typical vascular ring is interrupted by gaps other 

 than those due to the leaf-traces, and it may therefore be termed polystelic. In 

 addition there are two or three small accessory steles lying within the vascular 

 ring. Throughout the internode the course of these internal steles is quite free 

 from the vascular ring, but at each node one of them approaches the free margin 

 of the leaf-gap, and completely fuses with it, separating off again after the leaf- 

 gap has become filled up. 



Pteris elata var. Karsteniana has a typically solenostelic vascular ring, and 

 also possesses internal accessory steles, which behave in a manuer quite similar to 

 those of Dicksonia rithiyinosa \ but they are relatively larger, and frequently they 

 all fuse up together so as to form a second, inner, completely closed vascular 

 ring. 



It is suggested that the several internal steles and vascular rings that occur m 

 the Saccolomas and in Matonia pectinata are also of the same origin and nature 

 as those described above. 



The relation of the internal accessory steles in certain Cyatheas to those of 

 the above-mentioned ferns is also discussed. 



