November 9, 191 1] 



NATURE 



59 



A further communication by the same author described 

 I some experiments on the wilting of moorland plants, in 

 which he attempted to determine directly the phj-siological 

 water-content of moorland soils. 



Palaeobotanical Papers. 

 Friday morning was chiefly occupied by the communica- 

 lion of palaeobotanical papers. 



Miss M. Kershaw described the structure and develop- 

 ment of the ovule of a cycad, Bowenia spectabilis, dealing 

 j particularly with the complicated pollen-chamber of this 

 j genus. Miss Kershaw, and also several speakers in the 

 discussion which followed, compared the ovule with certain 

 1 fossil seeds, especially Trigonocarpon. 



j Dr. M. J. Benson read a paper on a new type of 



j synangium, which she attributed to Heterangium Grievii. 



The author maintained that the discovery of this early 



langium affords support to the synangial theory of the 



•d. 



j Dr. D. H. Scott, F.R.S., who followed, dealt with the 



' structure and relationships of a rare Palaeozoic fern, Zygo- 



j pteris Grayi. This species possesses a five-rayed stellate 



stele, with internal xylem consisting of narrow tracheides 



• embedded in parenchyma. Dr. Scott is inclined to regard 



j this type of stele as an elaborated protostele rather than 



I a condensation of a more complex vascular system. 



I Mr. H. Hamshaw Thomas gave a general account of 



I recent researches on the Jurassic plants of Yorkshire. 



Amongst other things described were several new fossils 



found by Mr. Thomas himself, e.g. a new Bennettitalian 



" flower " with microsporophylls as well as ovules, and a 



fruit-like body containing seeds. To the latter he has 



given the name Caytonia. The discussion which followed 



centred mainly about the probable nature of this apparent 



fruit. 



Prof. A. C. Seward, F.R.S., gave an account of the 

 structure of a petrified Williamsonia collected by Hugh 

 Millar in north-east Scotland, and figured by him in " The 

 Testimony of the Rocks." The specimen, of which 

 sections have been cut by permission of the director of the 

 Royal Scottish Museum, Edinburgh, consists of a central 

 conical axis bearing immature interseminal scales and 

 seeds, the whole being enclosed by linear bracts bearing 

 numerous unicellular hairs. The structure of the plant 

 will be fully described in a forthcoming paper. In com- 

 menting on this paper in the discussion. Dr. Scott re- 

 marked that we know nothing at present about the young 

 stages of the ovules in any Bennettitales. 



From the examination of serial sections through entire 

 boulders of calciferous sandstone from Pettvcur, Miss T. 

 Lockhart was led to results which confirm' Dr. Gordon's 

 view that petrifaction of the plant remains in these boulders 

 occurred in thermal pools. 



Cytological Papers, cS-c. 



(Jytological papers, &c., were taken on Friday afternoon. 



■|"he first paper was one contributed by Dr. A. A. 

 Lawson, on nuclear osmosis as a factor in mitosis. 

 The results obtained by the author are at variance in 

 several respects with those of previous observers. He 

 finds that the nuclear membrane does not break down and 

 disappear, but persists as a permeable plasmatic membrane. 

 During mitosis, the nuclear sap diffuses through this mem- 

 brane, which consequently closes in around the chromo- 

 somes, the nuclear cavity becoming much reduced. The 

 author further maintains that the spindle threads are 

 merely a drawing out of the cytoplasmic reticulum bv the 

 receding membrane. They thus represent lines of tension 

 m the cytoplasm. They neither invade the nuclear cavity 

 nor aid in drawing the daughter chromosomes to the poles 

 of the spindle. 



Dr. H. C. I. Eraser next gave a paper on the longi- 

 tudinal fission of the meiotic chromosomes in Vicia Faha. 

 ihis paper was a continuation of one communicated at 

 the Sheffield meeting. The chromosomes undergo longi- 

 tudinal fission during the telophase of the last archesporial 

 division. The V-shaped chromosomes undergo a second 

 longitudinal fission at the poles of the heterotypc spindle. 

 Both fissions are recognisable until the chromosomes pass 

 on to the homotype spindle. The second fission disappears 

 during metaphase, but is again visible when the chromo- 

 somes come into contact at the poles. 



NO. 2193, VOL. 88] 



Mr. T. G. B. Osborn gave an account of the life-cycle 

 and affinities of the Plasmodiophoraceae. A cvtological 

 investigation of the life-history of Spongospora su'bterranea 

 showed a very close similarity to that described for certain 

 genera of the Plasmodiophoraceae by Maire and Tison. 

 The chief difference was that in Spongospora a fusion of 

 nuclei in pairs occurred after the akaryote condition. 



Mr. A. S. Home followed with a paper on somatic 

 nuclear division in Spongospora Solani, in which a peculiar 

 form of karyokinesis was described as occurring during the 

 early stages of the life-history. 



The proceedings on Friday were terminated bv a paper 

 from Mr. A. E. Lechmere, on some West African fungi. 

 Amongst others, a series of interesting forms were isolated 

 which apparently belong to a new genus of Pyrenomycetes. 

 Mr. ^echmere illustrated his paper bv photographs and 

 also living cultures. 



The Semi-popular Lecture 

 The semi-popular lecture this year was given bv Dr. 

 Francis Darwin, F.R.S., the subject being "The Balance- 

 sheet of a Plant." The lecture was exceedingly interest- 

 ing and full of apt illustration, and was much appreciated 

 by a crowded audience. Dr. Darwin explained that the 

 " balance-sheet " of the title referred to the water supplv 

 of the plant. The lecture cannot be fully noticed here, but 

 it may be mentioned that Dr. Darwin adduced some con- 

 vincing experiments of his own to show that Lloyd's con- 

 tention that transpiration is not regulated by movements 

 of the stomata is contrary to fact. 



Miscellaneous Papers. 



Wednesday morning was occupied by a series of miscel- 

 laneous papers and reports of committees. 



Mr. Mangham read a paper in which he gave the results 

 of further work on the translocation of sugars by sieve- 

 tubes. The investigation had been extended to Laminaria, 

 and crystalline osazones were found in the cortical cells,, 

 sieve-tubes and hyphae of two species of this genus, especi- 

 ally at the time of formation of the .new lamina in 

 L. digit at a. 



Prof. W. B. Bottomley dealt with the structure and 

 functions of the root-nodules of Myrica Gale. He con- 

 cluded that these nodules are concerned with the assimila- 

 tion of atmospheric nitrogen, as are those of Cycas, Alnus, 

 and other plants. 



Another paper by the same author described some experi- 

 ments on the effect of bacterioto.xins on the growth of 

 plants. An aqueous extract of manure was found to have 

 an injurious effect on the germination of seeds and on the 

 subsequent growth of the seedlings. The harmful effect 

 (which could be prevented by heating the extract) appeared 

 to be due to bacteriotoxins, probably of the nature of 

 toxalbumoses. 



Mr. A. S. Home suggested that the Cornaceae are poly- 

 phyletic. This hypothesis is the result of a comparative 

 study of the flower in the Cornaceae and allied orders. The 

 uniovular condition and other resemblances in the order are 

 regarded merely as cases of parallelism, the evolutionary 

 history being different in different cases. 



Sir Daniel Morris, F.R.S., directed attention to the- 

 recent and rapid spread of Oidium euonymi-japonicae in 

 southern England, and urged that steps should be taken to 

 prevent the mischief caused by this pest. 



Owing to the limited time available, and the absence of 

 the authors, the following papers were taken as read : — 

 the chromosomes of the hybrid Primula kewensis, by Miss 

 L. Digby ; and a note on the flora of Shetland, with some 

 reference to its ecology, by Mr. W. West. 



Reports of Committees. 

 Reports were presented by five research committees : — 

 (i) The experimental study of heredity. The following 

 summary of the report will indicate the scope of the work 

 carried on. The experiments on the inherilanre of double 

 flowers have been continued. In the case of stocks, the 

 results have now shown that this character is inherited in 

 accordance with definite, though somewhat complicated, 

 laws. Similar experiments have also been carried out on 

 several other genera, chiefly biennials (carnation, holly- 

 hock, &c.). These have now been carried to the third 



