68 



NA TURE 



[November i6, 1899 



Mr. R. H. Bififen (Cambridge) contributed some notes on 

 india-rubber. Caoutchouc is a constituent of the latex of many 

 plants belonging chiefly to the Euphorbiacere, Apocynacese and 

 Urticaceas, that is, of plants characterised by the possession of 

 laticiferous cells as distinct from vessels. Caoutchouc occurs 

 as small particles in latex ; if a reagent is added which will 

 cause coagulation, the particles run together in strings and form 

 a moss-like mass of rubber with the watery portions of the latex 

 entangled within it. Two physical processes are now being 

 used. (I) The latex, mixed with water, is strained and 

 churned ; the thick cream which rises to the surface is pressed 

 through rollers and converted into rubber. (2) The author's 

 process consists in separating the rubber with a centrifugal 

 apparatus. Details are given in the paper regarding the 

 chemical properties of the different kinds of rubber obtained 

 from Hevea, Castilloa, Manihot, Finis, Hancornia, Kidsia, 

 Artocarpus and Ciusia. The author also raises some questions 

 of theoretical interest with regard to possible relations between 

 caoutchouc, starch and resin-bodies, and indicates lines for 

 further inquiry. 



Flowering Plants, &c. 



Mr. J. C. Willis, of Peradeniya, Ceylon, read a paper of 

 exceptional merit, illustrated by numerous lantern slides, on 

 the morphology and life-history of the Indo-Ceylonese 

 Podostemaceae. 



The paper read was an abstract of a forthcoming monograph 

 of the Indian and Ceylon species of this very remarkable order 

 of water plants, in which the various species will be described 

 in detail both morphologically and ecologically. A few typical 

 species were described and their life-history explained, showing 

 the extraordinary modifications which the vegetative system has 

 undergone to suit the needs of life in rising and falling water 

 and in rapid currents. The vegetative organs consist largely of 

 modified roots forming thallus-like bodies, and bearing leafy or 

 floral endogenous shoots, and branching themselves in an exo- 

 or endo-genous manner. The conclusion was drawn that the 

 «ndo- or exo-genous origin of an organ or a branch is a 

 phenomenon of an adaptive nature in these plants, and to a 

 large extent in others also. The adaptive modifications of the 

 structure, such as the gradual reduction, through a series of 

 forms, of the shoots and leaves, the increased multiplication of 

 the shoots by vegetative budding, the reduction of the number 

 of flowers per shoot, and the change to anemophily, the increased 

 dorsiventrality and other characters, were shown to be rather 

 correlated with the rise and fall of the water than with the 

 velocity of the stream. In conclusion, some of the more general 

 -questions of morphology were discussed in the light of the 

 observations made on these plants. 



Prot. Douglas Campbell (California) gave a short account of 

 work in progress on the development of the flowers and embryos 

 of various species of Aracese. 



The materials for the author's investigations were collected 

 mostly in Jamaica, and include species of Dieffenbachia, Agla- 

 ^nema, Philodendron and AnthtirUim. A study was also made 

 of Lysichiton of Pacific North America. 



A study of the development of the ovule indicates that the 

 primitive form is axial, as in other low monocotyledons ; the 

 early development of the embryo-sac follows the ordinary type. 

 Later there is a multiplication of the antipodal cells, and the 

 sac becomes filled with endosperm at an early stage. The ovule is 

 often massive, and there is a marked development of mucilage- 

 secreting hairs upon the funiculus and the base of the nucellus. 

 In all forms so far examined the embryo is destitute of a 

 suspensor, and the cotyledon is very large, sometimes suggesting 

 the scutellum of the grass-embryo. 



The forms with a single carpel are probably most primitive 

 and most nearly related to the other low monocotyledons. 



Mr. G. Dowker gave a description of the sand dunes between 

 Deal and Sandwich, with remarks on the flora of the district. 



The author in this paper gave an account of the formation of 

 •the dunes and mud-banks, claiming for them the reclamation of 

 the large tract of sand from the sea, mostly since the Roman 

 occupation of Britain-. He referred to the Acts of Parliament 

 passed prohibiting the destruction of the mat grass, which con- 

 tributed so largely to the preservation of the hills, and lamented 

 that nothing was done to prevent the wholesale gathering of Sea 

 holly by men who ruthlessly destroyed it by taking it away to 

 sell. He recounted his long experience and knowledge of the 

 district, dating back to his schoolboy days with the Rev. J. 



NO. 1568, VOL. 61] 



Lay ton, a distinguished botanist of Sandwich. He particularised 

 the following rare or characteristic plants as denizens of the 

 hills : Allium vineale, A. compactum, Poa bulbosa, Hippophae 

 rhamiioides, Sileiie conica, Orobanche caryophyllacea, Lepidhim 

 latifolium, and on the salt marshes, Atriplex pedunculata, 

 Frankenia levis, Aster Tripolium, and PolypOi^on monspeliettsis. 

 The author added a list of over 300 species of flowering plants 

 to be met with in the district. 



Miss Dale (Cambridge) presented a paper on intumescences 

 of Hibiscus vitifolitis. 



The plants on which the observations were made were grown, 

 directly or indirectly, from seed from Somaliland. The in- 

 tumescences, which vary in size and shape, occur on the leaves, 

 stems, green parts of the flower, and on the young fruit. Some 

 are entirely colourless ; others are green at the base. On the 

 leaf the intumescences are either purely epidermal or partly sub- 

 epidermal ; and on the stem the outgrowths are more complex 

 and usually larger. 



A number of seedlings were planted in separate pots, and 

 allowed to grow under identical conditions. They all de- 

 veloped intumescences, and were all very much alike. When 

 each had about nine or ten leaves, and was beginning to flower, 

 the plants were placed under different conditions, and examined 

 at the end of six weeks. 



The experimental evidence points to the conclusion that the 

 intumescences are pathological, and are due neither to insects 

 nor to fungi, but to the direct effects of environment. The form- 

 ation of outgrowths appears to be caused by excessive moisture 

 combined with a high temperature. If the temperature is low 

 the plants do not appear to have strength to form them. The 

 production of outgrowths seems to be a response on the part of 

 the plant to insufficient transpiration. 



Fossil Plants, &c. 



Prof. Bertrand (Lille) described the structure of a stem of a 

 ribbed Sigillaria. The specimens oi Sigillaria hitherto described 

 anatomically are species with a smooth bark, but no account has 

 so far been published of the structure of an undoubted Sigillaria 

 belonging to the Rhytidolepis section. The species described by 

 Prof. Bertrand exhibits external characters recalling those of 

 Sigillaria elongata. The primary wood, which forms a continuous 

 ring, agrees with that of the stems previously described as Diplo- 

 xylon ; it is enclosed externally by a zone of secondary wood. The 

 primary xylem is characterised by the prominent ridges or points 

 on its external face, the projecting points corresponding with the 

 grooves on the surface of the stem. In the immediate neigh- 

 bourhood of the origin of a leaf-trace, the small tracheal elements 

 form a median band in the middle of a sinus on the face of the 

 corona. Each leaf-trace passes outwards through a medullary 

 ray of the secondary wood ; it consists solely of primary ele- 

 ments. The author compared his specimen with Sigillaria 

 spinulosa and with Diploxyton stems from Halifax, Oldham and 

 Burntisland. The central cylinder of the ribbed Sigillaria 

 differs from that of a Phanerogam in the manner of origin of the 

 leaf-traces, and in the structure and centripetal development of 

 the primary wood. 



Prof. F. E. Weiss ( Manchester) communicated a paper on a 

 biserial Halonia belonging to the genus Lepidophloios. 



At the Bristol meeting of the British Association, Dr. D. H. 

 Scott exhibited photographs of this Halonia from the Hough 

 Hill Colliery, Stalybridge, and pointed out the agreement of its 

 structure with that of Lepidodendron fuliginostim of Williamson. 

 Dr. Scott had generously allowed the author to undertake the 

 further examination of the specimen, and this confirmed the 

 identity of the internal structure of the Halonia with that of 

 Williamson's Lepidodendron fuliginostim. 



The same structure is shown also by stems of the ordinary 

 multiseriate Halonias, which, as Kidston and Potonie have 

 shown, belong undoubtedly to the genus Lepidophloios. Stems, 

 therefore, showing the structure o{ Lepidodendron fuliqinosum, 

 Williamson, should be referred to the genus Lepidophloios. 



The fruiting branches of this genus, however, termed Halonia, 

 or halonial branches, have usually a number of rows of spirally 

 arranged tubercles. The Hough Hill Halonia has only two 

 rows of tubercles ; hence it would by some palseobotanists be 

 classed as Ulodendroid, but it seems belter to call it a "biserial 

 Halonia," since the name of Halonia has been reserved by 

 Kidston and others for the fruiting branches of Lepidophloios, 

 and also because its elevated tubercles distinguish it from the 

 usually depressed Ulodendroid scars. 



