ay 4 4 , Wa tite" ‘ i Y wy he A ats fi CORR Cnn hs “eisai : h 7 Pare nee enn Pay Pitty f) 4 i i rah athe anne NN rh Nt citaaeh ae Una ht ees stan a Neveen ‘ " ees ‘A SRS ne Hien whevteth , Saitatbtataey rR AN RH ta sae ns i i AHS Naa PIP ‘ che ors 1 ath ' i a) ' ah bf Fe te A NG Stee Seen Riot ant rafaldteagey ngs DO NTR DOT On ; 7 Di “ Wane Ranh ae or y " ., ots 9 Os Wi Ba: ne Virb Nis DORKS h * , eel set wine Ward t HG Niitanso cohen alga aca i if Win, on ane PUGH ULAR a Rn a PY FeO Nare he tne Oe iet : eee eye i eilgpee mite BORGO UIE URL aA a anata a i MCAS : relent ACN YOM RT TEU TEN Mk Eo TF r Hult Kt ay ATL bate sN, y 5 as 'y » D Ob ' 5 ; Ce A PO t ie ale, PMT One EL DCR er ats Rtv WES ie a en key ahd tet Ta SRT Leas ty tba) fia’ Sie ty Cae Nt tebe sabe at ote eter) “Aes Foe be ahh Utara Walaa se PAGS nant silt eb os had cH ese r OD uta ee Mis SRM RS ibe ae ean eit ats eR ai i ory tit ie tats Wihhiirhiattae a Cu aieat “ ; an i emery aroha diet Be Lt a Pe Sip a 4 Mater Th eneiit a teahna DEP RRHTSae hii Tea eaiat tata aati sears ergy unt : Comer a ‘ ; Waived th i Pyare eG FV de Pea bb rear sh i teeraefed aaah Wl ode rae We eva ba eae Ys Se NE t TOL HN ENCE] Tha ale Aes ener 20 bie, Vita aa asia’) Re EN ie rae E a Vue Petts Fy saunas ti ee Wit) ie ras 4 faa car port auar tow eih Vara Ub early dee be COCs an tis bribes 3 Whe ‘ Rote ith TRA re i Mesa wat hed ih 0 STOUR er earn oy eas Nees nt iets ey Y ao rk at eaR asa wh a 1 ak wags ear yh ti Hoenn nit fl We gg tka Carnn aN Cia ‘; Rew) " Bi; ret cule, fh THE SCIENTIFIC PROCEEDINGS ROYAL DUBLIN SOCIETY. Ney Series. VOLUME XIV. DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY LEINSTER HOUSE, DUBLIN. WILLIAMS & NORGATH, 14 HENRIETTA STREET, COVENT GARDEN, LONDON, W.C. 1913-19195. THE Society desires it to be understood that it 1s not answerable for any opinion, representation of facts, or train of reasoning that may appear in this Volume of its Proceedings. The Authors of the several Memoirs are alone responsible for their contents. Dusuin : PrintEp at THE University Press ry PonsonBy AND Girns. 576 ©. IS ( 563 ) INDEX TO VOLUME XIV. Action of Pectase (BATL), 349. Ascent of Sap, Quantitative Examination of the Klements of the Wood of Trees in Relation to the supposed I’unction of the cells (Drxon and Miss E. S. Marsuatn), 388. Atkins (W. R. G.). Oxydases and their Inhibitors in Plant Tissues, 144. ~ Oxydases and their Inhibitors in Plant ‘Tissues. Part [].—lhe Flowers and Leaves of Iris, 157. Oxydases and their Inhibitors in Plant Tissues. Part Il]: The Localiza- tion of Oxydases and Catalase in some ‘Marine Alge, 199. —w— Oxydases and their Inhibitors in Plant Tissues. Part 1V.—The Flowers of Iris, 317. Atkins (W. R G.) and G. 0. SHurrarp. Pigments of Fruits in relation to some Genetic xperiments on Cupsicum annuum, 328, Ball (Nigel). Action of Pectase, 349. Borboride and Ephydride in the Haliday Collection, Dublin, Notes on the Speci- mens of (CoLLIN), 235. Bothrodendron kiltorkense, Haught. Sp.: its Stigmaria and Cone (Jonnson), 211. Brown (William). Fatigue of Nickel and Tron Wires when subjected to the In- fluence of Alternating Magnetic Fields of Frequency 50 per second, 336. Note on the Change of Length in Nickel Wire due to small Longitudinal Loads and Low Alternating Magnetic Fields, 297. SCIENT. PROC. R.D.S., VOL. XIV., INDEX. Brown (William). Subsidence of Tor- sional Oscillations and latigue of Nickel Wires when subjected to the In- fluence of Alternating Magnetic Fields of Frequencies up to 250 per second, 621. — Subsidence of Torsional Oscilla- tions of Iron Wires and Alloys when subjected to the Influence of Alternating Magnetic Fields of Frequency 50 per second, 393. Brown (W.) and J. Surrg. Subsidence of Torsional Oscillations in Nickel Wires when subjected to the Influence of Alternating Magnetic Fields, 215. Buoyancy of the Seeds of some Britannic Plants. (PRarewr), 13. Butler (J. Bayley) and John M. SHexman. Preliminary Account of a New Oeda nometer for Measuring the Expansive Force of Single Seeds, or Similar Small Bodies, when wetted, 462. Cancerous Growths, Search for Thorium in (Jony), 345. Carpenter (George H.) and Thomas R. Hewitr. The Reproductive Organs and the Newly Hatched Larva of the Warble- fly (Hypoderma), 268. Change of Length in Nickel Wire due to Small Longitudinal Loads and Low Alternating Magnetic Fields (Brown), 297. Changes in Soils brought about by Heat- ing (Miss A. Witson), 513. Changes produced in the Sap by the Heat- ing of Branches (Drxon), 224. 4x 564 Index. Collin (J. E.). Notes on the Specimens of Borboride and some Ephydride in the Haliday Collection at the National Museum, Dublin, 235. Deep-sea Deposits, Investigation of the (Joly), 256. Dixon (Henry H.). Changes produced in the Sap by the Heating of Branches, 224. ——— Note on the Spread of Morbid Changes through Plants from Branches killed by Heat, 207. —— On the Tensile Strength of Sap, 229, Dixon (Henry H.) and W. R. G. ATKINS. Extraction of Zymase by means of Liquid Air. (Preliminary Note), 1. Osmotic Pressures in Plant- Organs. II[1.—The Osmotic Pressure and Electrical Conductivity of Yeast, Beer, and Wort, 9. Osmotic Pressures in Plants. IV.—On the Constituents and Concen- tration of the Sap in the Conducting Tracts, and on the Circulation of Carbo- hydrates in Plants, 374. Dixon (Henry H.) and Miss E, S. Marsuaty. Quantitative Examination of the Elements of the Wood of Trees in Relation to the Supposed Function of the Cells in the Ascent of Sap, 258. Osmotic Pressures in Plants. V.—Seasonal Variations in the Concen- tration of the Cell-Sap of Some Deciduous and Evergreen Trees, 445. Doyle (Joseph). Researches in Experi- mental Morphology. I.—On the Change of the Petiole into a Stem by means of Grafting, 408. Effect of a Low Potential Electric Current on Photographie Plates (G11), 74. Extraction ot Zymase by means of Liquid Air. (Preliminary Note.) Drxon and Arkins), 1. Example of the Multiple Coupling of Mendelian Factors (WIzson), 369. Fatigue of Nickel and Iron Wires when subjected to the Influence of Alternating Magnetic Fields of Frequency 450 per second (Brown), 336. Faunal Zones of the Rush-Skerries Car- boniferous Section, Co. Dublin (SmyrxH), 536. Frit-fly, Larva and Puparium of the (Hewirr), 313. Fruits, Pigments of, in Relation to some Genetic Experiments on Capsicum annuum (ATKINS and SHWRRARD), 328. Further Observations on Phytophthora erythroseptica Pethyb., and on the Disease produced by it in the Potato Plant (PETHYBRIDGE), 179. Gill (Rev. H. V.). Effect of a Low Poten- tial Electric Current on Photographic Plates, 74. Ginkgophyllum (Jounson), 169. Grafting, Change of the Petiole into a Stem by means of (Dore), 405. kultorkense sp. nov. Haigh (W. D.). Method for the Estima- tion of Hygroscopic Moisture in Soils, 529. Hartley (W.J.). Violet Colouring -Matter and its production by a certain Bac- terium, 63. Hewitt (Thomas k.). Larva and Puparium of the Frit-fly, 313. Hygroscopic Moisture in Soils, A Method for the Estimation of (Haren), 529. Investigation of the Deep-sea Deposits (JoLy), 256. Johnson (T.). Lothrodendron kiltorkense, Haught. Sp.: its Stigmaria and Cone, 211. ——— Ginkgophylium kiltorkense sp. nov., 169. Joly (J.). Investigation of the Deep-sea Deposits, 256. ——— Local Application of Radium in Therapeutics, 290. —-—— Kadio-Therapy: Its Scientific Basis and its Teaching (Jory), 421. ——— Search for Thorium in Cancerous Growths (Joxy), 345. Knowles (Matilda C.). The Maritime and Marine Lichens of Howth, 79. Index. 565 Larva and Puparium of the Frit-fly (Hewirr), 313. Lichens of Howth, Maritime and Marine (Matilda C. Know ss), 79. Local Application of Kadium in Thera- peutics (Joy), 290. Maritime and Marine Lichens of Howth (Matilda C. KNowrss), 79. Mendelian Problems (WILson), 302, 369, 481. Method for the Estimation of Hygroscopic Moisture in Soils (HateH), 529. Morbid Changes, spread of, through Plants, from Branches killed by Heat (Drxon), 207. Morphology, some Researches in Experi- mental (Dorun), 405. Nickel and Iron Wires, Fatigue of, when subjected to the Influence of Alternating Magnetic Fields (Brown), 336. Nickel and Iron Wires, Subsidence of Tor- sional Oscillations in, when subjected to the Influence of alternating Magnetic Fields (Brown), 215, 393, 521. Nickel Wire, change of length in, due to small Longitudinal Loads and Low alter- nating Magnetic Fields (BRown), 297. Oedanometer, Preliminary Account of a New, for Measuring the Expansive Force of Single Seeds, or Similar Small lodies, when wetted (BurLER and SHERIDAN), 462. Osmotic Pressures in Plant-Organs. I11.—The Osmotic Pressure and Elec- trical Conductivity of Yeast, Beer, and Wort (Dixon and Arxtns), 9. Osmotic Pressures in Plants. IV.—On the Constituents and Concentration of the Sap in the Conducting Tracts, and on the Cireulation of Carbohydrates in Plants (Dixon and AvrKins), 374. V.—Seasonal Variations in the Con- centration of the Cell-Sap of some De- ciduous and Evergreen Trees (1xon and ATKINS), 445. Oxydases and their Inhibitors in Plant Tissues (ATKINS), 144. Part I1.—The Flowers and Leaves ef [ris (ATKINS), 157. Oxydases and their Inhibitors in Plant Tissues, Part I11: The Localization of Oxydases and Catalase in some Marine Algze (ATKINS), 199. ——— Part IV.—tUhe Flowers of Iris (Arkins), 317. Pectase, Action of (BALL), 349. Pethybridge (George H.). Further Ob- servations on Phytophthora erythrosep- tica Pethyb., and on the Disease produced by it in the Potato Plant, 179. Photographic Plates, Itffect of a Low Potential Electric Current on (GILL), 74. Phytophthora erythrosepticu, Further Observations on (PiTHYBRIDGE), 179. Pigments of Fruits in Relation to some Genetic Experiments on Capsicum annuum (ATKINS and SHERRARD), 328. Plant Tissues, Oxydases and their Inhi- bitors in (ATKINS), 144, 157, 199, 317. Polygamous Mendelian Factors (JAMES Witson), 302. Praeger (R. Lloyd). Buoyancy of the Seeds of some Britannic Plants, 13. Preliminary Account of a New Oeda- nometer for Measuring the Expansive Force of single Seeds, or similar small Bodies, when wetted (Burner and SHERIDAN), 462. Quantitative Examination of the Elements of the Wood of Trees in Relation to the Supposed Function of the Cells in the Ascent of Sap (Drxon and Miss E. 8. MaRsHaL), 358. Radio-Therapy: Its Scientific Basis and its Teaching (Jozy), 491. Radium in Therapeutics (Jony), 290. Reproductive Organs and Newly Hatched Larva of the Warble-Fly (Hypoderma) (CARPENTER and Hewirr), 268. Researches in Experimental Morphology. I.—On the Change of the Petiole into a Stem by means of Grafting (DoyLE), 405. Rush - Skerries Carboniferous Section, Faunal Zones of the (SMyTH), 989. Sap, changes produced in, by the Heating of Branches (Drxon), 224. Sap, Tensile Strength of (Drxon), 229. 566 Index. Search for Thorium in Cancerous Growths (Jozy), 345. Seeds, A New Oedanometer for Measuring the Mxpansive Force of Single Seeds when wetted (Burner and SaERIDAN), 462. Seeds of some Britannic Plants, Buoyancy of the (PxaxeER), 13. Simplified Solutions of certain Mendelian Problems in which Factors have In- separable Effects (James Wixson), 481. Smyth (Louis B.). On the Faunal Zones of the Rush-Skerries Carboniferous Section, Co. Dublin, 538. Soils, Changes in, brought about by Heating (Miss A. Witson), 513. Specimens of Borboride and some Ephy- dride in the Haliday Collection at the National Museum, Dublin (Coli), 239. Spread of Morbid Changes through Plants from Branches killed by Heat (Drxon), 207. Subsidence of Torsional Oscillations and the Fatigue of Nickel Wires when sub- jected to the Influence of Alternating Magnetic Fields of Frequencies up to 250 per second (Brown), 521. Subsidence of Torsional (scillations in Nickel Wires when subjected to the Influence of Alternating Magnetic Fields (Brown and SmirH), 215. Subsidence of Torsional Oscillations of Iron Wires and Alloys when subjected to the Influence of Alternating Magnetie Fields of Frequency 50 persecond (Brown), 393. Tensile Strength of Sap (Dixon), 229. Thorium in Cancerous Growths, Search for (Jory), 345. Violet Colouring-Matter and its production by a certain Bacterium (Hartiey), 63. Warble-Fly (Hypodermu), Reproductive and Newly Hatched Larva of the (CARPENTER and HEwIrT), 268. Wilson (James). Example of the Multiple Coupling of Mendelian lactors, 369. Polygamous Mendelian Factors, 302. Simplified Solutions of certain Mendelian Problems in which Factors have Inseparable Effects (James Wit- son), 481. Wilson (Miss A.). Changes in Soils brought about by Heating, 513. Wood of Trees, Quantitative Mxamination of, in Relation to the supposed Function of the Cells in the Ascent of Sap (Dixon and Miss E. S. MarsHat1), 358. Zymase, Extraction of, by means of Liquid Air (Drxon and Arxkins), 1. END OF VOLUME XIV. CONTENTS. VOL. XIV. No. I.—The Extraction of Zymase by means of Liquid Air. (Preliminary Note.) By Henry H. Dixon, so.p., r.z.s.; and W. R. G. Arxins, M.A., $0.B., A.I.c. (May, 1913.) Il.—Osmotic Pressures in Plant-Organs. III.—The Osmotic Pressure and Hlectrical Conductivity of Yeast, Beer, and Wort. By Henry H. Drxon, so.p., r.z.s.; and W. R. G. ATKINS, M.A., SC.B., ato. (May, 1913.) I1I.—On the Buoyancy of the Seeds of some Britannic Plants. By R. Luoyp Prazcer. (May, 1913.) IV.—On a Violet Colouring-Matter and its production by a certain Bacterium. By W. J. Harruny, p.a. (July, 1913.) V.—The Effect of a Low Potential Electrie Current on Photographic Plates. By Rev. H. V. Guu, s.z., B.a. (Plates I. and II.) (July, 1913.) ViI.—The Maritime and Marine Lichens of Howth. By Marmopa C. Kwnowxies. (Plates I[].-IX. and Map.) (August, 1913.) VII.—Oxydases and their Inhibitors in Plant Tissues. By W. R. G. Arxins, sc.B., A..c. (August, 1913.) : 0 VIII.—Oxydases and their Inhibitors in Plant Tissues. Part I].—The Flowers and Leaves of Iris. By W. R. G. Arxins, sc.B., A.I.C. (January, 1914.) . IX.—Gumkgophyllum kiltorkense sp. nov. By T. Jounson, D.Sc, F.L.S. (Plates X-XII.) (February, 1914.) X.—Further Observations on Phytophthora erythroseptica Pethyb., and on the Disease produced by it in the Potato Plant. By Groren H. Peraysrings, pu.p., B.so. (Plate XIII.) (January, 1914.) XI.—Oxydases and their Inhibitors in Plant Tissues. Part III: The Localization of Oxydases and Catalase in some Marine Alge. By W. R. G. Arxins, so.B., a.t.c. (January, 1914.) PAGE 13 63 74 79 144 157 169 179 199 lv Contents. No. XII.—Note on the Spread of Morbid Changes through Plants from Branches killed by Heat. By Henry H. Drxon, sc.p., F.Rs. (February, 1914.) XIII.—Bothrodendron kiltorkense, Haught. Sp.: its Stigmaria and Cone. By T. Jonson, p.sc., r.u.s. (Plates XIV-XVIII.) (February, 1914.) : XIV.—The Subsidence of Torsional Oscillations in Nickel Wires when subjected to the Influence of alternating Magnetic Fields. By W. Brown, s.sc., and J. Smrrn, u.a. (February, 1914.) XV.—Changes produced in the Sap by the Heating of Branches. By Henry H. Dixon, sc.p., r.r.s. (March, 1914.) XV1.—On the Tensile Strength of Sap. By Henry H. Dixon, so.p., F.R.s. (March, 1914.) XVII.—Notes on the Specimens of Borboride and some Hphydrid@ in the Haliday Collection at the National Museum, Dublin. By J. E. Coun, F.z.8., F.E.s. (April, 1914.) XVIII.—On the Investigation of the Deep-sea Deposits. By J. Joly, sc.v., F.R.S. (Plates XIX, XX). (April, 1914.) XIX.—The Reproductive Organs and the Newly Hatched Larva of the Warble-Fly (Hypoderma). By Gurorcn H. Carpenter, B.sc., M.R.1.4., and THomas R. Hewirt, a.R.c.sc.1. (Plates XXI-XXVI.) (April, 1914.) XX.—On the Local Application of Radium in Therapeutics. By J. Jouy, so.D., F.R.s. (May, 1914.) XXI.—Note on the Change of Length in Nickel Wire due to Small Longitudinal Loads and Low Alternating Magnetic Fields. By Wituiam Brown, s.sc. (May, 1914.) XXII.—Polygamous Mendelian Factors. By Jams Witson, m.a., B.SC. (June, 1914.) XXIII.—The Larva and Puparium of the Frit-fly. By Tuomas R. Hewrrv, a.R.c.sc.1. (Plate XXVII.) (June, 1914.) XXIV.—Oxidases and their Inhibitors in Plant Tissues. Part IV.—The Flowers of Ins. By W. R. G. Arxus, so.p., F.1.c. (January, 1915.) XXV.—The Pigments of Fruits in relation to some Genetic Experiments on Capsicum Annuwum. By W.R. G. Arnis, sc.d., F.I.c., and G. O. Suerrarp, a.R.c.sc.1. (January, 1915.) PAGE 211 215 224 229 235 256 268 290 297 302 313 317 328 Contents. No. XXVI.—The Fatigue of Nickel and Iron Wires when subjected to the Influence of Alternating Magnetic Fields of Frequency 50 per second. By Wituiam Brown, z.sc. (January, 1915.) é : é : : ; é XXVII.—Search for Thorium in Cancerous Growths. By J. Jony, sc.p., F.R.S. (January, 1915.) XXVIII.—On the Action of Pectase. By Nicer G. Batu. (January, 1915.) XXIX.—A Quantitative Examination of the Elements of the Wood of Trees in Relation to the Supposed Function of the Cells in the Ascent of Sap. By Henry H. Dixon, sc.p., r.z.s., and Miss EH. 8. Marswaty, B.a. (January, 1915.) XXX.—An Example of the Multiple Coupling of Mendelian Factors. By James Witson, M.a., B.sc. (January, 1915.) XXXI.—Osmotic Pressures in Plants. IV.—On the Constituents and Concentration of the Sap in the Conducting Tracts, and on the Circulation of Carbohydrates in Plants. By Henry H. Drxon, sc.p. (DUBL.), F.R.s.; and W. R. G. Arxins, sc.p. (puBL.), F.1.c. (February, 1915.) XXXII.—The Subsidence of Torsional Oscillations of Iron Wires and Alloys when subjected to the Influence of Alternating Magnetic Fields of Frequency 50 per second. By W. Brown, 8.sc. (March, 1915.) XXXIII.—Some Researches in Experimental Morphology. I.—On the Change of the Petiole into a Stem by means of Grafting. By Josrpn Doyen, B.a., m.sc. (Plates XXVIJI-XXXIV.) (March, 1915.) XXXIV.—Osmotic Pressures in Plants. V.—Seasonal Variations in the Concentration of the Cell-Sap of some Deciduous and Evergreen Trees. By Henry H. Dixon, sc.p. (DUBL.), F.R.S. ; and W. R. G. Arxins, sc.p. (puBL.), F.t.c. (March, 1915.) XXXYV.—A Preliminary Account of a New Oedanometer for Measuring the Expansive Force of Single Seeds, or Similar Small Bodies, when wetted. By J. Bayney Burner, M.a., M.B. ; and Joun M. Sueriman, 8.a., m.sc. (March, 1915.) . XXXVI.—Simplified Solutions of certain Mendelian Problems in which Factors have Inseparable Effects. By Jams Witson, ™.a., B.sc. (April, 1915.) XXXVII.—Radio-Therapy: Its Scientific Basis and its Teaching. By J. Joy, sc.p., F.R.S. (April, 1915.) b 358 369 374 393 405 445 462 481 491 v1 ' Contents. No. XXXVIII.—Changes in Soils brought about by Heating. By Miss A. Witson, B.a. (May, 1915.) : XXXIX.—The Subsidence of Torsional Oscillations and the Fatigue of Nickel Wires when subjected to the influence of Alternating Magnetic Fields of Frequencies up to 250 per second. By Wittiam Brown, s.sc. (June, 1915.) : XL.—A Method for the Estimation of Hygroscopic Moisture in Soils. By W. D. Haren, z.sc., a.n.c.sc.1. (July, 1915.) XLI.—On the Faunal’ Zones of the Rush-Skerries Carboniferous Section, Co. Dublin. By Louis B. Smyru, 8.a., B.sc. (Plates XXXV-XXXVII.) (August, 1915.) PAGE 513 521 529 535 THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. WolewI VS CNIS) eNOGhs te plas Tope 2 MAY, 1913. THE EXTRACTION OF ZYMASE BY MEANS OF LIQUID AIR. (Pretiminary Nore.) BY HENRY iL DIXON, SDD), IW R.S., UNIVERSITY PROFESSOR OF BOTANY, TRINITY COLLEGE, DUBLIN ; AND W. R. G. ATKINS, M.A., Sc.B., A.L.C., ASSISTANT TO THE PROFESSOR OF BOTANY,- TRINITY COLLEGE, DUBLIN. .;_. -> [Authors alone are responsible for all opinions expressed in their Communications. | DUBLIN: — PUBLISHED BY THE ROYAL DUBLIN SOCIETY, LEINSTER HOUSE, DUBLIN. : WILLIAMS AND NORGATE, 14, HENRJETYTA STREET, COVENT GARDEN, LONDON, W.C. 1913. Price Sixpence. Roval Dublin Society. Oe FOUNDED, A.D. 1731. INCORPORATED, 1749. EVENING SCIENTIFIC } MEETINGS. Tur Scientific Meetings! of the Society are held alternately at 4.30 p.m. and 8 p.m. on the third Tuesday of every month of the Session (November to June). Authors desiring to read Papers before the Society are requested +0 forward their Communications to the Registrar of the Royal Dublin Society at least ten Jays prior to each Meeting, as no Paper can be set down for reading until examined and approved by the Science ‘Committee. The copyright of Papers read becomes the property of the Society, and such as are considered suitable for the purpose will be printed with the least possible delay. Authors are requested to hand in their MS. and necessary Illustrations in a complete form, and ready for transmission to the Editor. THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. 1 THE EXTRACTION OF ZYMASE BY MEANS OF LIQUID AIR. (Pretiminary Nore.) By HENRY H. DIXON, 8c.D., F.R.S., University Professor of Botany, Trinity College, Dublin ; AND W. R. G. ATKINS, M.A.,S8cB., A.1.C., Assistant to the Professor of Botany, Trinity College, Dublin. {Read Apri 15. Published May 23, 1913.] Recentiy we found it possible to obtain the sap from various plant-organs without change in concentration, by pressure after the organ was immersed for a few minutes in liquid air (Dixon and Atkins, 1), It seems that the exposure to the intense cold renders the protoplasm permeable, and the pressure forces out the solution from the vacuoles unchanged. This suggested the probability that similar exposure of the yeast-cell would render its protoplasm permeable, and that the zymase and other endo-enzymes would then be free to escape. Experiment has confirmed this surmise.' Our experiments up to the present have been made with ‘liquid yeast,” supplied to us from Guinness’s Brewery, through the kindness of Mr. A. McMullen. This is the top yeast skimmed off the vat after the 1Tt is remarkable that Pasteur failed to extract zymase by freezing yeast (Harden, 3). Probably the temperature he employed was not below the eutectic point of the cell-solutes. That this point may have to be exceeded to kill a cell has been shown by Maximow (8). SOIENT, PROC. R,D.S., VOL. XIV., NO. I. B 2 Scientific Proceedings, Royal Dublin Society. fermentation of the wort is almost complete. From this the beer is removed by centrifuging, or by pressing through a fine linen cloth. The yeast, then a plastic mass, is made up into cylinders 10-15 cm. long, and 1:5 cm. diameter, and wrapped in paper. In this form it is lowered by means of a thread into a Dewar flask containing liquid air.’ It is left immersed for ten or fifteen minutes till the cessation of active ebullition of the air indicates that the mass has fallen to the temperature of the liquid air. The cylinder is then withdrawn from the flask, the paper is removed from its lower end, and it is transferred to the tube of the centrifuge. As it thaws, the yeast runs down out of its paper covering into the tube. It is remarkable that the yeast, which before the application of liquid air was a sticky, plastic mass, has now, after exposure to the intense cold, become quite fluid. This change of consistency is observed even when condensation of atmospheric moisture on the cold and thawing mass is precluded. Centrifuging for ten minutes, at 9000 revolutions per minute, causes the yeast-cells to sink in this fluid mass, and to leave a faintly opalescent brown liquid above. The volume of this liquid is about 80 per cent. of the volume of the plastic yeast frozen, and represents the juice or sap of the treated yeast- cells. This liquid has powerful fermentative properties, and contains zymase. In one of the first experiments carried out in this manner, we took 160 c.c. of pressed yeast, froze, thawed, and centrifuged it in the manner described, thus obtaining 60 c.c. yeast sap. To 50 cc. of this, 20 grammes cane-sugar was added, and the mixture was introduced into an Erlenmeyer flask in a thermostat at about 33°C. The flask was connected by means of a rubber tube leading out of the thermostat to two gas-burettes connected in series. The CO, evolved displaced mercury from the first burette into the second. When reading the volume, the mercury in the two was adjusted so as to stand at the same level. This arrangement, which was found quite convenient, was adopted in all the experiments. Before each reading the fermenting fluid was thoroughly shaken. EXPERIMENT 1, Time. Volume of CO2 hr. min. in ¢.¢c. 24 25 : d ; 32:0. 26 40 ; : : 36°5. No further evolution of gas. 1 As in our previous work, we are indebted to Professor W. H. Thompson for the liquid air used in these experiments. Drxon ano Atkins—Lxtraction of Zymase by Means of Liqud Air. 3 No antiseptic was added in this experiment, but it is evident that the high sugar concentration checks bacterial action. A similar experiment gave the following figures, the same quantities being used, with the addition of about 0°5 ¢.c. of toluene :— EXPERIMEN’ 2. Time. Volume of OOz in c.c. 6 hours, : ; 39°2. 18 hours, : : . 65:2. No further evolution of gas. In this experiment the liquid at air-temperature was saturated with CO.,, so that some of the gas evolved and caught in the burette was CO, driven off by the initial rise of temperature due to the transference into the thermostat at 31°C. In another experiment with similar quantities, to which toluene was also added, the liquid was not saturated with CO., and the following figures were obtained :— EXprErimMeEnt 3. Time. Volume of COz hr. min. in’ ¢:c. 0 40, : ; ; 8:6. il &, : : : 1D. OOM Wee) Hits a 00-01 No further evolution of yas. In this experiment some of the same sample of sap was used as in the previous experiment (No. 2). In the meantime (14 hours) the sap was standing at ordinary room-temperature, and was presumably losing some of its fermentative efficiency. Notwithstanding this, it exhibited a very fair activity. It was also noticed that while standing no evolution of CO, took place. This indicates that the sap obtained by the liquid-air method is practically free from glycogen or other fermentable carbohydrates. The absence of fermentation from the supernatant liquid is in marked contrast to the behaviour of the solid sediment. When the liquid is poured off, the sediment froths actively, and in this respect behaves like the thawed frozen yeast before centrifuging. Presumably the glycogen retained within the cells is hydrolysed by the action of glycogenase which now has access to it, giving fermentable sugars. The zymase present is thus provided with a substrate. B 2 & Scientific Proceedings, Royal Dublin Society. It is of interest to compare the activity of the fluid extracted by means of the liquid air in the manner described with that extracted from yeast-cells by other methods. In 1912 Lebedeff (4) described a method of extracting zymase from yeast by simple maceration. His method consists essentially in drying the yeast at 30°, and in macerating it for two hours at 35°C. with three times its weight of water, or for a longer period at a lower temperature. ‘To compare the two methods the following experiment was made :—the beer was pressed off some “liquid yeast ” and two samples of the solid yeast (4 and Beach about 100 g.) were made. A was dried at 30°C. for twenty-four hours, and weighed 25 g. The temperature was kept for three days at 35°C., and the yeast lost 0:4 g. To the dried solid 75 ¢.c. of water and a little toluene were added, and it was left to macerate for two hours at 35°C. It was then centrifuged and yielded 41 cc. of liquid. 30 ¢.c. of this was put in the conical flask | with 12g. sugar and a little toluene. The production of CO, is given below :— A (18) B (12) By Maceration. By Liquid Ar. Time Volume of Time Volume of hr. min. COz2 hr. min. COz 0 10 : : : 0°8 0 50 : : ; 87 6 40 : : : 13°53 ES. : : : 11:0 54 25 : 3 : 25'8 3 25 ; : : 19:0 9 40 : : : 30'0 In column & are given the volumes of CO, produced by 30 c.c. of yeast- sap extracted by means of liquid air under similar conditions. The 100 g. of the solid yeast in this case yielded a little over 32¢.c. sap. Calculation from the foregoing data shows that each gramme of fresh yeast afforded a total fermentation-volume of 0°35 c.c. CO, by Lebedeff’s method, and 0°37 ¢.c. by liquid-air extraction. From this comparison it appears that the fluid extracted from the sample of yeast by means of liquid air is quite as active as that obtained by the maceration method. This experience was confirmed by another experiment where the mace- ration was effected at 20°-25°C. and a larger volume of water added, viz. :— to 21 g. of dried yeast 100 c.c. of water was added and maceration proceeded for twenty-one hours. As before, 30 c.c. of the fluid with 12 g. of sugar and a Dixon anv Arxkins—LEetraction of Zymase by Means of Liquid Air. 5 little toluene was used. Under B and C the activity of the same sample of yeast extracted by liquid air is given. A(8) B(6) C (5) By Maceration. By Liquid Air. By Liquid Ar. Time. Volume of | Time. Volume of | Time. Volume of hr. min. COz. hr. min. CO, | hr. min. COz. Q 25 : : 40, i 8) 5 ; 8:0 0 30 : : 3:4 MAb) 4 ; 8'6 Bo ® 4 a ASG 040 . : 8:6 8) Ils : 9°8 AES cS 3845 . 1d4 28) @ 4 ay alae AGS) . §20:°0 |10 45 . Rol) 18 40. . 3848 Correction for dilution shows a total evolution of CO, amounting to 0:33ec, 038eac., 0'34cec. per gramme of undried yeast in A, B, and C respectively. In this case, allowing for the dilution of the liquid obtained by maceration, its activity is again practically identical with that obtained by the liquid air method. Some of the same yeast furnished a comparison of the method described by Giglioli (2); 100 g. of the solid yeast was mixed with 5 cc. of chloroform. The mass became semi-fluid and frothed so vigorously that some 2 c.c. of the fluid was lost. After six hours’ standing 100c.c. of the fluid was centrifuged, and yielded 36 c.c. liquid, including chloroform. To 50 c.c. of this 12 g. of sugar was added, and it was set to ferment. Its activity, which was great at first, rapidly decayed. Experiment 4. Time. Volume of hr, min. COz. i @ ; : 5 PAVE No further fermentation, This is equivalent to 0°22 e.c. of CO, per gramme of yeast. It is possible that maceration for a shorter period would yield a more active liquid, or perhaps the same result might be attained by using a smaller amount of chloroform. The generally low activity of the juice extracted by all these methods from the yeast at our disposal suggested that possibly the enzyme was impaired during the extraction. In the following experiment it was sought to render the zymase more stable by furnishing it with fermentable material immediately on its exit from the cells. With this object acccordingly, to 67 grammes of this solid yeast, while still frozen, was added a solution containing 23¢.c. of water, 18 g. of sugar, and a little toluene. Experience had showed that 67g. of yeast would yield about 23c.c. of yeast-juice ; 6 Scientific Proceedings, Royal Dublin Society. therefore, the juice was diluted with about its own volume of water ; 40 c.c. of the mixture was allowed to ferment. The volumes of CO, evolved are recorded under A. For comparison under B is recorded the evolution of CO, from 40¢.c. of a mixture made up of 20 cc. of yeast-juice extracted by the liquid-air method without a substrate, and 20 c.c. of water and 15 g. of sugar under similar conditions. A (9) B(i1) Time. Volume of Time. Volume of hr. min. COz. hr. min. CO2. 0 20 : : L 8:0 0 50 : ; i 10°8 1 15 : 5 : 12:2 2 § 3°6 4 50 : : : 23°6 Sen : 58 5 10 5 ; : 23°6 425 . : : 6:0 18 10 : 2 ; 26°6 10 45. ; 3 10°6 20 45 . ; : 27:0 12 20 : : : 11:0 No further evolution of gas. After correcting for volume-changes, owing to the addition of sugar, the above results correspond to an evolution of 0°57 ¢.c. for A and 0°19 cc. CO, for B per gramme of yeast. This comparison strongly supports the idea that the small activity of the yeast juice, and its rapid decay, are in part due to the action of a proteo- clastic enzyme, the action of which is partly inhibited by the combination of the enzyme with the sugar. How far the absence of suitable phosphate and co-enzyme are limiting factors must be examined later. In order to see if much zymase was retained in the sedimented yeast-cells after centrifuging, 50 g., the solid residue of Experiment 6, was mixed with 50 cc. of water, and extracted for twenty-four hours at room-temperature. The semi-fluid mixture on being centrifuged yielded 37 c.c. liquid. 30c.c. of this, with 12 g. of sugar and a small quantity of toluene, gave volumes of CO, as follows :— EXPERIMENT 7. Time. Volume of COz. hr. min. 0 10 : : : 5°9. 1 40 : ; sos 13 20 ; : 5 BOY. No further evolution of gas. Dixon anp Atxins—Eztraction of Zymase by Means of Liquid Air. 7 The above figures correspond to 0°57 cc. CO, per gramme of residue or 0:29 ec per gramme of fresh yeast, as against 0'38c.c. given by the juice from the fresh yeast. These figures clearly show that a large amount of zymase is retained by the. cells. It is also remarkable that the cells, after exposure to liquid air, are capable of taking up and retaining water, indicating that a condition of equilibrium is not yet attained, although the membranes are permeable. Culture experiments with the sediment showed that the exposure to the liquid air had killed the yeast. In the hopes of obtaining part of the zymase remaining behind in the cells we allowed a sample of frozen yeast to thaw in five times its weight of water, and to macerate for twenty-four hours at room-temperature. After centrifuging, 30 c.cs. of the supernatant liquid, with 12 ¢. sugar, were set to ferment under the usual conditions. EXPERimMent 10. Time. Volume of CO2. hr. min. 0 10 : : 3 48. 0 50 : : : S56. 1 45 : 3 5 L2G, 3. 0 : : > ALAR. 4 35 ‘ : 13°0. No further evolution of gas. From this table it is clear that the actual amount of zymase extracted may be much increased by dilution and maceration, as the yield was 2:2 c.c. of CO, per gramme of yeast. Of course the concentration of the enzyme is greatly reduced. It appears then that the liquid-air method is as efficient as Lebedeft’s method. It has the advantage of being very rapid. It requires only 30-40 minutes to prepare the zymase-containing fluid from the solid yeast. Also the time for changes taking place in the enzyme is reduced to a minimum. The ease of the extraction of zymase by liquid air suggests its application to the extraction of other endo-cellular bodies from bacteria, &c. This point one of us is at present investigating along with Dr. A. Stokes. Finally, another possible use of this method may here be suggested. It is generally held that sterilized food-stuffs are less assimilable owing to the 8 Scientific Proceedings, Royal Dublin Society. destruction of the enzymes of the tissues. By our experiments it has been shown that, by means of liquid air, sap containing enzymes may be extracted from cells without serious alteration. This sap, frozen immediately after extraction, might be evaporated to dryness as ice under reduced pressure, as described by L. F. Shakell (5), and the resulting powder stored and added to the food as desired, to replace the enzymes lost by sterilization. BIBLIOGRAPHY. 1. Drxon, H. H., and Arkriys, W. R. G.: Osmotic Pressures in Plants, I.—Methods of Extracting Sap from Plant Organs. Scient. Proc. Roy. Dubl. Soe., vol. xiii (N.S.), 1913, p. 422. 2. Giertom1, J.: Della probabile funzione degli olii essenziali e di altri prodotti volatili delle piante, quale causa di movimento dei succhi nei tessuti viventi. Rendic. Acc. Lincei, vol. xx, 2° sem. 1911, p. 349. 8. Harpen, A.: Alcoholic Fermentation. Longmans, Green, & Co., London, OTs lo: 4, Lepeperr, A.: Extraction de la Zymase par simple Macération. Ann. VInst. Pasteur, tom. xxxvi, 1912, p. 8. 5. Maximow, N. A.: Chemische Schutzmittel der Pflanzen gegen Erfrieren. Ber. der Deut. Bot. Gesellschaft. 1912, Bd. 80, Heft. 2, s, 52. 6. Suaxett, L. F.: An Improved Method of Desiccation, with some applications to Biological Problems. American Journal of Physiology, vol. xxiv, 1909, p. 326. THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. Vol. XIV. (N.8.), No. 2. MAY, 1913. OSMOTIC PRESSURES IN PLANT-ORGANS. I11.—TwHe Osmotic Pressure AnD EvectricaL ConbDUCcTIVITY or YEAST, Beer, AND Wort. BY HENRY H. DIXON, Sc.D., F.R.S., UNIVERSITY PROFESSOR OF BOTANY, TRINITY COLLEGE, DUBLIN ; AND W. R. G. ATKINS, M.A., Sc.B., A.LC., ASSISTANT TO THE PROFESSOR OF BOTANY, TRINITY COLLEGE, DUBLIN. [Authors alone are responsible for all opinions expressed in their Communications. | DUBLIN: PUBLISHED BY THE ROYAL DUBUIN SOCIETY, LEINSTER HOUSE, DUBLIN. WILLIAMS AND NORGATE, 14, HENRIETTA STREET, COVENT GARDEN, LONDON, W.C. 1913. ise son i ee ES Price Sixpence. PAI: | NOV 242 +44" >\ NS ae Pes Roval Dublin Society, ee FOUNDED, A.D. 1731. INCORPORATED, 1749. EVENING SCIENTIFIC MEETINGS. Tue Scientific Meetings of the Society are held alternately at 4.30 j.m. and 8 p.m. on the third Tuesday of every month of the Session (November to June). Authors desiring to read Papers before the Society are requested +0 forward their Communications to the Registrar of the Royal Dublin Society at least ten Jays prior to each Meeting, as no Paper can be set down for reading until examined and approved by the Science Committee. The copyright of Papers read becomes the property of the Society, and such as are considered suitable for the purpose will be printed with the least possible delay. Authors are requested to hand in their MS. and necessary Illustrations in a complete form, and ready for transmission to the Iditor. JH OSMOTIC PRESSURES IN PLANT-ORGANS. IIl.—Tue Osmortc PressurE and Execrrica Conpnucriviry oF Yeast, Beer, and Wort. By HENRY H. DIXON, Sc.D., F.RS., University Professor of Botany, Trinity College, Dublin ; AND W. R. G. ATKINS, M.A., Sc.B., A.LC., Assistant to the Professor of Botany, Trinity College, Dublin. [Read Aprin 145. Published May 24, 1913.] In view of the rapid metabolism of the yeast-cell as regards carbohydrates a study of the osmotic equilibrium between it and the solution which it ferments seemed to be of interest. It has recently been demonstrated by Paine (5) that alcohol penetrates the yeast cell readily, a state of equilibrium being soon reached in which the ratio of alcohol in the cell to that outside is a constant, deviating only slightly from 0°85, Salts, on the other hand, penetrate to a small extent, the ratio of the internal and external concentrations being no more than 0:1-0:25, except in the case of poisonous substances. Indeed, it is an open question how much of this apparent absorption is really due to adsorption on the surface. To determine the osmotic pressure the method of thermo-electric eryoscopy (1) was employed. The unaltered yeast-juice was obtained by freezing the dry material in liquid air and centrifuging the resulting fluid mass as described in detail in our account of zymase extraction (3). The electrical conductivity of the juice, beer, and wort was also determined, to give an idea of the relative proportions of electrolytes and non-electrolytes concerned in the production of osmotic pressures. The apparatus was the usual one, which we employed in previous work (2). All specific conductivity measurements were carried out at 0°, and are recorded as reciprocals of the resistance in ohms, not in Siemens’ units. SCIENT. PROC., R.D.S., VOL. XIV., NO. II. Cc 10 Scientific Proceedings, Royal Dublin Society. Through the kindness of Mr. A. McMullen of the Guinness Research Laboratory, we were supplied with both pressed yeast and that skimmed from the vats with adhering beer. The beer was removed by centrifuging or by pressing through a linen cloth by hand. In Table I are recorded the results thus obtained, A being the depression of freezing-point, P the osmotic pressure in atmospheres calculated from A, and ¢ the specific electrical conductivity at 0°. Tanne I. Ton Liquid, A P C x 108 582 | Sap of washed Bakers’ Yeast, : 1-064 | 12°80 780 583 », pressed Brewers’ Yeast, - | 4:082 49°10 596 593 eae i : . | 3870 | 40:53 671 598 | ene 5 PS . | 4600. | 55:34 607 585 | Wort, ; : aif seni 14-16 149 594 Re : 4 : : 1:247 15:00 150 597 | No. 594 fermented 7 days in ona | | vessel in Laboratory, 3 | 1545 18°58 207 From the above figures it may be seen that, both in osmotic pressure and electrical conductivity, pressed yeast gives values which are much higher than those of wort. Baker’s yeast, however, gives a low osmotic pressure, but a high conductivity even after washing. The figures afforded by the sap of yeast and by the surrounding nutritive fluid may be seen in Table II, p. 11. On comparing the results given by beer with those of wort it is at once apparent that while the electrical conductivity remains much the same, the osmotic pressure becomes approximately three times as great during fermenta- tion, when interrupted at the usual stage in the commercial process. Very complete fermentation, however, judging from the single experiment we performed, occasions a fall in osmotic pressure after the initial rise, and is accompanied by a marked increase in the conductivity (see Table I, No. 597). It is, however, possible that the conditions of this fermentation were abnormal, and there was probably considerable loss of liquid by evaporation. The above-mentioned experiment is substantiated by No. 609, which is the beer of No. 606 allowed to stand at air-temperature in a closed vessel with a little yeast. It will be noted that there isa fall in pressure, but a slight rise in conductivity. Dixon anp Atxins—Osmotic Pressures in Plant-Organs. 11 Turning now to the yeast in Nos. 595, 598, 612, the osmotic pressure of the juice is much higher than that of the beer, corresponding in two cases to a difference in freezing-point of about 0°5°. In these cases the yeast was separated from the beer by centrifuging to remove adherent liquid as completely as possible, and was then frozen. ‘This process occupies some Tasie IT. ee Liquid. A B Cox 108 595 Sap of Yeast, : a ¢ 3°907° | 47-00 518 598 a aa : y ‘ 3:815° | 45°88 558 607 a », Which was kept separated from beer for 6 hours before | freezing, : : o 3°367° 40°51 608 610 Sap of Yeast separated from beer kept 24 hours before freezing, . 37243 39°00 742 611 Sap of Yeast (same sample as in 610) suspended 24 hours in running water, . 0 9 3°166 88°09 653 612 Sap of Yeast, : 0 6 3°730 44°85 562 592 Beer of No. 595, _ | 3-407 41°10 123 596 », of No. 598, . : . 3°655 43-96 125 606 », of No. 607, 2 : 5 37417 41:10 132 609 No. 606 kept 6 days, : 6 2°996 35°22 145 615 No. 606 kept 7 days, 5 si oe = 146 608 Beer of No. 610, . 9 . | 38460 41-62 146 614 No. 608 kept 24 hours, : | _ = 146 613 Beer of No. 612, . 3 : 3°188 38°34 147 time. In No. 612, where it was effected as rapidly as possible, less than one hour elapsed between the separation and the freezing in liquid air. In this case the divergence between the osmotic pressure of the yeast and of the beer was the greatest observed. In Nos. 607 and 610 yeast was allowed to stand for six hours and twenty-four hours respectively after separation before freezing. The results here show a diminution in pressure, owing most probably to respiratory changes, so that it has fallen slightly below that of the beer from which it was removed. From Nos. 610 and 611 it appears that this decrease in osmotic pressure takes place whether the yeast is kept dry or suspended in water. This rapid falling off shows very likely the normal rate of consumption of carbohydrate with the resulting increase in conductivity. 12 Scientific Proceedings, Royal Dublin Society. Such a lessening of pressure is under ordinary circumstances made good by the diffusion inwards of sugar from the wort, hence this carbohydrate must be able to pass freely into the cell, while the alcohol produced passes out, maintaining a constant ratio, as shown by Paine (/oc. cit.). A well-marked but relatively small extra fall in pressure was observed in No. 611, where the yeast, after separation from the beer, was suspended in a linen cloth in a large vessel of water with a delivery tap and overflow. The small degree of permeability of the yeast as regards electrolytes is clearly brought out by the conductivity of the juice being from four to five times that of the beer. Even allowing for fluctuations from sample to sample there is a well-marked rise in conductivity in yeast after its separation. While this may be due in part to decreasing viscosity of the sap owing to sugars having been used up, yet, quantitatively considered, this explanation seems insufficient, and Nos. 610 and 611 make it more probable that such a: result is partly due to the retention of an acid produced in fermentation, which in the normal course would diffuse very slowly outwards. Succinic acid, for instance, and its more highly ionised ammonium salt have been shown by Ehrlich (4) to arise during fermentation from glutamic acid. To avoid the possibility of error in the comparison of yeast-juice and beer owing to the expulsion of gases by freezing the former solid, measurements were made of both freezing-point and conductivity of beer as separated from yeast and after freezing solid. No appreciable difference was observed between the two sets of figures. BIbLioGRAPHY. L. Drxson, H. H., ann Arxtns, W. R. G.: On Osmotic Pressure in Plants: and on a Thermo-Hlectric method of determining Freezing-points. Scient. Proc. Roy. Dubl. Soc., vol. xii (N.S.), 1910, 275. 2. ——— Osmotic Pressures in Plants [I1.—Cryoscopice and Conduc- tivity Measurements on some Vegetable Saps. Scient. Proc. Roy. Dubl. Soc., vol. xiii (N.S.), 19138, p. 434. 3. ——— ——— The Extraction of Zymase by Means of Liquid Air. Scient. Proc. Roy. Dubl. Soce., vol. xiv (N.S.), 1913, p. 1. 4. Hnruicu, F.: Ueber die Entstehung der Bernsteinsiure bei der alko- holischen Girung. Biochem. Zeitschr., 1909, Bd. xviii, s. 391. 5. Painz, 8S. G.: The Permeability of the Yeast-Cell. Proc. Roy. Soc., Ser. B., vol. lxxxiv, 1911, p. 289. THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. Vol. XIV. (N.8.), No. 3. MAY, 1913. ON THE BUOYANCY OF THE SEEDS OF SOME BRITANNIC PLANTS. BY R. LLOYD PRAEGER. [Authors alone are responsible for all opinions expressed in their Communications. } DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY, LEINSTER HOUSE, DUBLIN. WILLIAMS AND NORGATH, 14, HENRIETTA STREET, COVENT GARDEN, LONDON, W.C. 1913. Tey(al MSIE oN ie “0, Price Two Shillings. MT eee eens NoV 22 i918 Ings 5 \ Roval Mublin Society. FOUNDED, A.D. 1731. INCORPORATED, 1749. See EVENING SCIENTIFIC} MEETINGS. Tur Scientific Meetings of the Society are held alternately at 4.30 pm. and 8 p.m. on the third Tuesday of every month of the Session (November to June). Authors desiring to read Papers before the Society are requested to forward their Communications to the Registrar of the Royal Dublin Society at least ten Jays prior to each Meeting, as no Paper can be set down for reading until examined and approved by the Science Committee. The copyright of Papers read becomes the property of the Society, and such as are considered suitable for the purpose will be printed with the least possible delay. Authors are requested to hand in their MS. and necessary Illustrations in a complete form, and ready for transmission to the Editor. eam] ITI. ON THE BUOYANCY OF THE SEEDS OF SOME BRITANNIC - PLANTS. By R. LLOYD PRAEGER. [Read Aprin 15. Published May 31, 1913.] In the present paper the term “seed” is used in its original and familiar sense, namely, that which is sown; in other words, the natural unit of dispersal. This may consist of a seed proper, or of one or more seeds enclosed in a dry or fleshy envelope, varying greatly in different species as regards size and shape. The capacity of seeds for remaining afloat in water is one which has a very important bearing on the subject of the dispersal and distribution of plants. Seeds which can float for weeks or months, or even in certain circumstances for a few days, may become widely spread by the agency of rivers and of lakes. If, in addition, they are capable of resisting the injurious effects of salt water, the power of floating becomes more important, conferring on the species possessing such seeds the possibility of dissemination across stretches of sea of greater or less extent. HISTORICAL SUMMARY. The importance of the floating power of seeds in relation to the geographical distribution of plants has been long recognized. The large and buoyant seeds and seed-vessels which strew the shores of tropical islands, with their suggestion of rapid and easy colonization by the aid of sea- currents, have been familiar to botanical travellers since the days of the earlier voyagers. So long ago as 1695, Sir Hans Sloane drew attention to foreign seeds thrown up by the sea on the shores of Scotland and Ireland’ ; these were the seeds of tropical plants, brought by the Gulf Stream from the West Indies. Darwin was the first to show that but a small proportion of flowering plants have seeds which float, although a large variety of seeds are not injured by even prolonged immersion in sea-water. He also found that by thoroughly drying certain seeds and seed-vessels, their floating power was materially 1 Phil. Trans., xix., pp. 398-400. 1696. SCIENT. PROC. R.D.S., VOL. XIV., NO. II. = G 14 Scientific Proceedings, Royal Dublin Society. increased; the same result was obtained in a few instances by drying fruiting branches of certain species, though such cases were exceptional. His conclusion is that, allowing for dried seeds and branches, about one-tenth of a flora might be taken as capable of transport across a considerable stretch of sea, and of subsequently germinating.’ Other early observations on the subject are well summed up by Martins,’ who himself performed a valuable series of experiments on seeds placed in sea-water. He selected 98 kinds of seeds, giving preference to large seeds with a thick coat, and to those of littoral plants. His results showed that the majority of these seeds floated on sea-water, about one-third sinking at once; also that one-third of the total were capable of germination after six weeks’ immersion, and one-eleventh after three months’ immersion. He concludes that the transport of seeds by currents plays an insignificant part in the dispersal of species between countries separated by sea. In 1873 Thuret® published the results of several seasons’ experiments on the same subject. He used seeds of 251 species, belonging to seventy-seven different orders. He demonstrated that the conclusion of Martins, that the seeds capable of floating in sea-water were twice as numerous as those incapable of the same, was incorrect as a generalization. Thuret attributed the error to want of thorough wetting of the seeds experimented on; but in a foot-note to the paper, Alphonse de Candolle points out that Martins, as has been stated above, selected seeds of high presumptive buoyaney—large seeds with thick coats, and seeds of littoral plants. Thuret’s detailed list shows that more than half of his 251 species sank at once; most of the remainder had sunk at the end of one or two days; only a very few floated fora week or more. ‘his result has been amply confirmed by subsequent observers. But just as Martins selected plants which gave a buoyancy percentage too high for general application, so Thuret erred on the other side. His list included very few littoral species, which, as a group, are now known to possess an especially high index of seed-buoyancy, and in consequence the 2 per cent. or so, which may be deduced from his tables as representing the seed- buoyancy of his plants,is too low to give an average figure for the seed- buoyancy of a flora. Many detailed observations followed on the dispersal of seeds by water, those of Scandinavian and Danish botanists, Kolpin Ravn‘ and Sernandex® for instance, being especially valuable. As regards our native flora, the 1 Origin of Species, ed. 6, pp. 506-509. ? Bull. Soc. Bot. de France, iy, p. 324. 1857. 8 Bibl. Univ. et Revue Suisse. Arch. des Sciences Phys. et Nat., N.P., xlvii, 179-194. 1873. 4 F. Korein Ravn: Om Flydeeynen hos Froene af vore Vand- og Sump-planter. Bot. Tids- skvift, xix. 1894. 5 R. SERNANDER : Den Skandinaviska Vegetationens Spridningsbiologie. Upsala and Berlin, 1901. Pranerr—The Buoyancy of the Seeds of some Britannic Plants. 15 most important series of observations are those of Guppy, who, in his exhaustive work on seed-dispersal in the Tropics,! furnishes much informa- tion relative to our native plants as well, including a buoyancy-table for 273 species. Those portions of his book which deal with the British flora constitute the main source of information relative to the buoyancy of the seeds of our native plants. His conclusion is that the seeds of 90 per cent. of the British flora sink either at once or within a few days, leaving 10 per cent. which alone possess buoyancy sufficient to render them capable of transference across any but a very narrow stretch of water. It will be noticed that this figure is identical with that arrived at by Darwin just half a century earlier, as representing the proportion of a flora capable of crossing, by means of currents, a considerable stretch of sea. His study of the buoyancy of Fijian and Hawaiian seeds led Guppy to adopt the same percentage as representing the seed-buoyancy of the flora of those regions. THE PRESENT EXPERIMENTS. The experiments of which the results are given below were undertaken in order to extend our knowledge of the buoyancy of seeds of plants which inhabit the British Islands, especially with a view of obtaining information useful in the study of the immigration and dispersal of our native flora. Until Guppy’s time, no special attention had been given to our native plants as regards their seed-buoyancy. Guppy, as stated above, tested the seeds of some 278 of these ; and he added to his table results for about 60 additional species, the seed-buoyancy of which could be obtained from the writings of Darwin, Martins, Thuret, Kolpin Ravn, and Sernander. In the present list, results are given for 786 species. ‘he number of species in Guppy’s list which were not tested by me is 114. Adding these figures, we have now buoyancy-results for just 900 species—a number which, though falling far short of the total for the British Isles, still represents a proportion sufficiently large to permit of a generalization regarding the whole flora. While Martins and Guppy experimented mainly with seeds .known or believed to have a high average of buoyancy, and thus obtained slightly abnormal results, I endeavoured to have all kinds of seeds equally represented in my experiments, whether the nature of the seeds themselves, the phylogenetic relationships of the plants which bore them, or their habitats, be taken into account. Since power of dispersal is to be measured by its maximum in the case of any species, special care was taken to test the seeds, so far as was possible, in the condition of maximum efficiency which may occur in nature. 1H.B.Guppy. Observations of a Naturalist in the Pacific . . . vol. ii: Plant-Dispersal. 1906. o 2 16 Scientific Proceedings, Royal Dublin Society. Thoroughly dry seed was used in preference to seed just taken from a fresh, moist seed-vessel ; though the latter is the condition in which the majority of seeds commence their dispersal-adventures, the former condition must frequently occur in nature. Seed gathered fresh and stored : in a dry room for some months was used in preference to any other. Fleshy fruits were tested in a thoroughly dried as well as in a fresh condition. Drying has often an important effect in the case of fleshy fruits, while in the case of hard seeds its effect is usually inappreciable. The experiments of Guppy’ showed that between fresh and salt water a very slight difference exists as regards their effect on the buoyancy of seeds. After a number of tests to satisfy myself of this, I fell back on the more easily obtainable medium, and used fresh water throughout the experiments, resorting to salt water occasionally as a check. There is hardly an exception to the rule that seeds which sink in the one medium sink also in the other. The only effect of the salt water is to slightly increase the period of flotation ; and since, as stated above, care was taken to obtain a maximum period by using dried seed (and also, as appears below, by taking the period of the most efficient seed of each batch as representing its buoyancy-period), I believe my figures are already quite as high as we have any right to accept as a buoyancy-index even for sea-water. The seeds, twenty to a hundred in number, whenever so great a number was available, were first cursorily examined for soundness, and then thoroughly shaken up-with water in test-tubes, care being taken to remove adherent air-bubbles. The minority which did not sink were kept, and examined and shaken up twice a day, and transferred to fresh water occasionally until all the seeds—excepting occasionally a few whose soundness there was reason to doubt—had sunk. This maximum period was then entered opposite the name of the species in a copy of the “ London Catalogue.” Thus, for those seeds which did not all sink within a minute or so, 12 hours is the unit of time, and signifies anything up to 12 hours ; and so on for greater periods. The maximum efficiency is thus not alone entered, but in many cases somewhat exaggerated; however, the exaggeration is unimportant except for short periods, and even then has little significance, as seeds of short flotation-periods are ineffective for oversea dispersal. After a flotation-period of a month or so, the seeds were examined and shaken up only once a day, and after about three months only once a week. In the case of a considerable number of species, the dispersal-unit may be either the whole fruit or part of it. In the majority of cases it is the seed itself. In many others it isa dry indehiscent fruit. In cases like the 1 loc. cit., p. 89. Prancer—The Buoyancy of the Seeds of some Britannic Plants. 17 species of Raphanus, it may be a portion of the fruit, with a seed enclosed. In the case of fleshy fruits, several conditions of dispersal are possible. A fresh berry may fall directly into a stream; or it may fall and get dried, and subsequently become immersed; or it may be eaten by a bird, and the wet seeds dropped into water, or dropped on a dry place and carried into a stream after dessication. So far as material served, buoyancy was tested under several or all of these conditions. Where material was obtainable, two or even three batches of seed of one species from different sources were tested. Sometimes the results obtained from different batches of seed were uniform; occasionally, they differed widely. To this point I shall return presently. Where more than one figure is given in the table opposite the name of a species, whether in the same column or in different columns, it represents the flotation-periods of the most buoyant seeds of different batches. EXPLANATION OF THE TABLE. In order that the varying buoyancy of the seeds of different species may be more readily discerned, the results obtained are arranged in five columns in the table which follows:—The cross in the first column shows the species whose seeds sink at once; the second column gives (in hours) periods up to one day; the third gives (in days) periods up to one week ; the fourth (in weeks) up to one month; the fifth gives (in months) periods over one month, up to 15 months, when observations ceased. The seeds which were still floating at the conclusion of the months’ observations are shown thus— 15 +. In a sixth column are added flotation-periods as given by Guppy. Guppy’s tabulated results are less detailed than my own, and a full comparison between the two cannot therefore be made. The form in which his observations are given, the symbols which he employs, and the symbols by which his results are shown in the sixth column of my table, are as follows :— Guppy’s symbol. Symbol in following list. Float for less than one week, : (blank) i » 1-4 weeks ? + 1-4 w. ,, 1-6 months, : ++ 1-6 m. Seno m i as, : vi ++ 6-12 m. » over 12 ,, : xii ++ 12 +m. Variable in floating power, ‘ var. var. ‘Guppy’s symbols, it will be seen, are comparable only to those given in the fourth and fifth columns of my table; results corresponding to those of my first three columns being shown by a blank in his table. 18 Scientific Proceedings, Royal Dublin Society. TABLE OF SEED-BUOYANCY. Name. Seeds all sunk in less than Guppy’s Days (1 to 7). Hours (1 to 24). One Minute. Weeks (1 to 4). results. * Months. 0-7 days. RANUNCULACEAE. Clematis Vitalba L., Thalictrum alpinum ZL., minus Z., ‘majus Orantz, . Anemone nemorosa L., Adonis annua L., Ranunculus trichophyllus Chaix, heterophyllus Weber, Baudotii Godron, Lenormandi F. Sehuitz, sceleratus L., Flammula L., Lingua L., Ficaria Z., auricomus L., repens L., bulbosus Z. parviflorus L., arvensis L., Caltha palustris L., radicans 7. F. Forst, Trollius europaeus Z., Eranthis hyemalis Salisd., . Aquilegia vulgaris L., Delphinium Ajacis Z., Actaea spicata L. (fresh fruit), (dry fruit), BERBERIDACEAE. Berberis vulgaris L. (fresh fruit), 50 (dry fruit), 3 80 (seed), | 1 bo | | oO KOK EX | — 6-12m. var. * — 6-12 m. var. Prarcur—Vhe Buoyancy of the Seeds of some Britannic Plants. Name. NYMPHAEACEAE. ' Nymphaea lutea Z. (dry seeds), . — PAPAVERACEAE. Papaver Argemone L., hybridum Z., Rhoeas, L., dubium Z., somniferum Z., . Meconopsis cambrica Vig., Glaucium flavum Crantz, Chelidonium majus L., FUMARIACEAE. Corydalis lutea DC., claviculata DC., Fumaria Bastardi Bor, officinalis Z., CRUCIFERAE. Matthiola incana R. Br., sinuata R. Br., Cheiranthus Cheiri Z., Radicula Nasturtium-aquaticum. R&B. palustris Moench, Barbarea lyrata Asch., Arabis hirsuta Scop. Cardamine flexuosa With., hirsuta Z., Hesperis matronalis Z., Sisymbrium officinale Scop., Irio Z., Sophia Z., . Thalianum J. Gay, orientale L., 19 TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Guppy’s results. oe One Hours Days Weeks = Minute. | (1 to 24). | (1to7). | (1 to 4). Mord. | = Gaye. = ee 12 Ber * x, x = = = = = xy 3 — — — = = x = - = = : x = = = a * xX = — a — = x = — =< = — x ES pores ale. pata, * x Xx = = = = =i = 2 = a ay — 12 ss = ae _ be 12 = = = = = 18 4 = = — ist zat 2 Ss as tie < — — — — — x, X = = a = aR x 12 — = = - = 3 — 12 — = x 3 = = = ‘ . ie ie ic Be i >< — — — — — x —_ Basis tes =, * x = — — = = x == a as aes = x, X = ae = rae a x — — = — — x a * >< — — oo — = 20 TABLE OF SEED-BUOYANCY—continued. Name. Seeds ali sunk in less than Scientific Proceedings, Royal Dublin Society. One Minute. Hours (1 to 24). Days (1 to 7). Weeks (1 to 4). | Months. Guppy’s results. Be, 0-7 days. Alliaria alliacea R. § B., Erysimum cheiranthoides Z., Camelina sativa Crantz, Brassica Napus L., Rutabaga DC., campestris L., Sinapis nigra L., arvensis L., alba Z., Diplotaxis muralis DC., Alyssum alyssoides L., Draba incana L., muralis L., verna L., Cochlearia officinalis L., danica L., anglica L., Thlaspi arvense L., alpestre L., Teesdalia nudicaulis R. Br., Lepidium Draba Z., . campestre &. Br. heterophyllum Benth., ruderale Z., sativum U. 0 perfoliatum Z., Capsella Bursa-pastoris Med., Subularia aquatica L., Coronopus didymus Si. Isatis tinctoria L., Cakile maritima Scop. (seed), Crambe maritima Z. (dry fruit), So (seed), x eS x S Citi iy, Gres aay 8 mlb. Gin tp Gay NED Ga ay, Gia ini Gate ae), aly. Gee, ese DRESS x x Prarger—The Buoyancy of the Seeds of some Britannic Plants. 21 TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Guppy’s Name. | HeSvIA sits and, ara ae 5. Months. ||| 0-7 days: Raphanus Raphanistrum L. 5 = = 5 = 4 (dry fruit). Ltd m0 (seed), : x | = = ne as j maritimus Sm. (dry fruit), = | = ae 33 a eek 0D (seed), ; « = = a = RESEDACEAE. Reseda alba L., 5 3 : — $ == _ = | = lutea Z., . F 5 ‘ x = = = ee | ie Luteola Z., . a 2 x — = | ms ee * CISTACEAE. Helianthemum Chamaecistus Wil, x = * Moxistinn Pay « ef 9¢ es a esa rks is VIOLACEAE. | Viola palustris Z., . ‘ % — | = 24 ce bat * odorata Z., 6 : 7 = = 1 == we et hirta Z., . C 0 : = 12 = = _ cs Riviniana Reich., b ‘ = 12 pas = ue sad canina Z., . 9 4 5 = 12 3 — — * arvensis Mwrr., . 0 0 = 12 = = = ies lutea Huds., : a a= = 13 pa fee ne Curtisii Forster, . 5 : = 18 poe a ent sty PoLYGALACEAE. Polygala vulgaris L., 0 ail ee SK — = — = * serpyllacea Weihe, . : x — = = = =e CARYOPHYLLACEAE. Dianthus deltoides L., : : x — = | = = as plumarius Z., 5 5 x — = = — a Caryophyllus Z., 3 ; x = = = = = Saponaria Vaccaria L., P 5 x — = = = pa officinalis Z., . : : x — = = = ee Silene latifolia R.g B., . : x — — — — * maritima With., : é x = = = = * anglica L., 5 5 21) ER OK — = = = es noctiflora Z., . ; Pe lt St = — = = = SCIENT. PROC., R.D.S., VOL. XIV., NO. Ill. D 22 Scientific Proceedings, Royal Dublin Society. TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Guppy’s a ) Hour D Weeks = Minute ell (asiorea) a (al to7). | (1to4). | Months. || 0-7 days. Silene acaulis L., x, X = = = — — Armeria L., x = = = = — Lychnis Viscaria Z., . x _— _— — — = alba Will., x, &X = = = = Elosecuculi Ibex, x _ _— — — = dioica L., x — — = — * Githago Scop., x = — _ _ = Sagina procumbens L., XG — — _— — * apetala Ard., SEEN — — = = a maritima G. Don. Ges — — = = ies subulata Presi, x — — = = Je nodosa Fenzl., x — _ = = ae Honkenya peploides Hhr., . — — 2 —_— _— 124m. Minuartia verna Hiern, x — _ = = Js tenuifolia Hiern, x = = == a ae Arenaria trinervia L., 35K — = — = poe serpyllifolia Z., x — — = = ae ciliata L., x — — = a yeas norvegica Gunn., . x — — = = — Stellaria media V%i1., x — — = = * palustris Retz., x — — _— a= — graminea L., x — — = = * Cerastium viscosum L., x — — = = es vulgatum Z., x — — = _ * semidecandrum L., x — — — = =e tetrandrum Curt., Sen NK — — = — = arvense L., . x — — =e = = Alsine rubra Crantz, . x — — = at * rupicola Hiern, ae. 4 — — = = ie media Crantz, x — a = a = marginata Reich., x = = = jets * * Spergula arvensis Z., Pranerr—The Buoyancy of the Seeds of some Britannic Plants. 25 TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Gunpyis Name. BEEN Minate ann aaa et SGA || WY CEE PoRTULACEAE. Montia fontana Z., x = = = = * ELATINACEAE. Elatine Hydropiper L., x — = = = * MALvaceEae. | Malva sylvestris L., _— — 13 — = * moschata L., — — 24 — pees | a rotundifolia Z., — 12 = a = | * Althaea officinalis Z., x = = — 2 | eat Lavatera arborea Z., . — 12 134 — — = HYPERICACEAE. Hypericum Androsaemum L., . x = = ee gue alts calycinum L., — 12 — == = — elatum Ait., —— = 1 = = | we quadrangulum Z., — = ] = os * perforatum Z., = 12 — = aa | * maculatum Orantz, x de =e pie say) Goll hae humifusum Z., x = oe as ae = linariifolium Vehl., x = — = = = hirsutum L., aS — = os os = pulchrum Z., x — — = = = elodes Z., — 12 ae aa <8 * GERANIACEAE. | Geranium sylyaticum Z., x = = = = ges pratense ., x = = = = | = sanguineum Z., . x Ox = = = = | = pyrenaicum Burm. fil., x = — = = es molle Z., en Se = == = =e a rotundifolium Z., KK — = = == a pusillum Z., x = = = oe = dissectum L., Seeds all sunk in less than Guppy’s Name. rea 128, GEE | eA Cc | sects | owiaa Gnaphalium uliginosum L., : x — = = as = sylvaticum L., . : : — 12 = ES = = Achillea Millefolium Z., . 3 — 12 1 ae = * Ptarmica L., 6 b : — — il = ps a Anthemis arvensis L., 6 0 — = ng pas = at Cotula Z., . 6 6 4 — = 2,2 = = a Matricaria inodora Z., a é — 12 ae = oe * discoidea DC., . ° : — 12 3 _—-: = & Parthenium L., Z $ — 12 ones as aah ar Chrysanthemum segetum L., . — 12 1} — — * Artemisia Absinthium Z., x = ears avic =a) * vulgaris Z., 4 — ok ee as * maritima L., : F : — = a 1 us a Tanacetum vulgare L., 9 A os 2 vals = aa aus Doronicum plantagineum Z., — 12 = = = = Senecio vulgaris Z., . 2 : — = 5E = = * sylvaticus Z., . F : — 18 = iat = pean viscosus L., 4 9 ; — a 1} = {= ee squalidus L., 0 6 a — = 2 ae uel = erucifolius Z., . 5 ; = 12 3 = os = Jacobaea L., ‘ é 3 _ 18 ete ae iy aus aquaticus Huds., 9 : — | — 1 == = * Bidens cernua L., : 0 : == | as ee 3 wee 6-12 m. tripartita L., : 0 : = | =s 5 = =e 6-12 m. Carlina vulgaris Z., . 0 ‘ = = 2 ahs | po pics Arctium majus Bernh., . : x om af = = = minus Bernh., 5 Sell RS CeUNK <= ae se = oes intermedium Lange, . 3 x = om = — — Newbouldii 47. Benn., 3 x = = = = — Centaurea nigra Z., . 5 ° — 12 pans = = — Cyanus L., 9 , . x os a5 a ees = Scabiosa L., ‘ ‘ : = = 2 = — — Onopordon Acanthium Z., . : = a oy ee peal Bs Prarger—The Buoyancy of the Seeds of some Britannic Plants. 33 TABLE OF SEED-BUOYANCY —continued. Seeds all sunk in less than Guppy’s Name. : ] resales, panes ioe fas, eR. NG ERS ||| AUS ea Carduus nutans L. é 5 = = 4 ze, ae * (without pappus), crispus Z. (without pappus) — 1} _ = = ee lanceolatus Z., = _ 3h ee re * pratensis Huds., . = == 4 14 Es BEL: Silybum Marianum Gaertn., — 18 = = — — Lapsana communis L., x = = ae = * Cichorum Intybus Z., = 1 2 ee ae Be Thrincia nudicaulis Britien, == — 12 ahs ae an Leontodon autumnalis L., . = = 1 pa = * Tragopogon pratensis L., = 12 pa = = * Picris hieracioides Z. (without x = = SE = = Helminthia echioides Cun. ce) = 12 1 _ 15 + 2 Lactuca Serriola Z., = 1z = = oe — virosa L., = 18 3 sade pees = muralis Gaertn., —_ 2 = = = = Taraxacum officinale Weber, = = 4 = == < Sonchus oleraceus L., = = ae pa = * asper Hill, — = 3 AES one ae arvensis L., = Ze 4 = = = Crepis capillaris Wally. (without x = = — — * biennis L., ease) = _— 1,13 —_— = = paludosa Moench, = 2 ae = = — Hieracium Pilosella Z., = 18 _ = — <= aurantiacum L., = = 6 = — = anglicum F7., ea = 2 — = — vulgatum F*., = 2 D) = = _— boreale Fr., = = 14, 2 = ues = CAMPANULACEAE. Lobelia Dortmanna L., x = = = — if Jasione montana L., x = = — —_— = Campanula glomerata L., . — 12 = — _— — latifolia Z., x = = _— = = 34 Scientifie Proceedings, Royal Dublin Society. TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Guppy’s results. * Name. One Hours Days Weeks Minute. | (1 to 24). | (107). | (1 to4). | Months. |) 0-7 days. Campanula rapunculoides Z., . x = = a eed ate rotundifolia Z., . — —_ 1 pa pt) ns ERICACEAE. Arbutus Unedo J. (fresh fruit). . x 39 (dry fruit), . x = oe ee oe ae aH (seed), x Arctostaphylos Uva-ursi Spreng. (dry fruit) | | | | | Calluna vulgaris Hvw/, Erica Tetralix L., << | | | | | cinerea L., mediterranea L., 0 : -= iy oe — = — = vagans L., . 5 5 — = 3h po es = Daboecia cantabrica Rk. § B., . — 1 — = == — Azalea procumbens L., ‘ - — 12 pee a Se pa Pyrola minor L., eto R : = — 24 — nas we PRIMULACEAE. Primula veris Z., 5 5 5 = 1 es wes wa pes elatior Jacq., 5 3 ‘ x = a = —_ == scotica Hook., 0 5 < — = aus pee pul Cicendia filiformis Delarbre, x = = ie = eS Gentiana Amarella L., — 1 — = = ae campestris L., x — — ee ith. te) verna L., x — — a — we POLEMONIACEAE. Polemoninm coeruleum Z., x _ — = aoe ae CoNnVoLVULACEAR. Convolvulus arvensis Z., — 12 — ee ee * Cuseuta Trifolii Bad., x _— — = == pa BoRAGINACEAE. Cynoglossum officinale Z., x = se Anchusa sempervirens L., a 12 — — = a Lycopsis arvensis L., a 12 —_— — — * Symphytum officinale Z., — — 23 — — Echium vulgare Z., — 2 _— = = oe Lithospermum officinale L., x — — = = * Amsinckia lycopsoides Lehm., _ 12 = — = — Myosotis seorpiodes Z., — 12 iy post = x caespitosa F. Schultz, = — 43 — = = arvensis Hili, = — 1 = = * SOLANACEAE. Solanum nigrum ZL. (fresh fruit), x, X — = _ — ) 2 Py) (dry seed), x = = ae a Duleamara ZL. (fresh fruit), x<5.-e4 — — — — * ” (dry seed), x == — tke aly ness Atropa Belladonna L. (fresh fruit), a _— 1, —_— — — 0 (dry seed), x a ao as Tapa ae Hyoscyamus niger Z., x — 13 = — = Datura Stramonium L., x 12 = — ee 36 Scientifie Proceedings, Royal Dublin Society. TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Gueevae Nance 3 results: teens ia) (en). esc Months. || 0-7 days. OROBANCHACEAE, Orobanche major L., . = 3 = _ — — rubra Smith, = 12 2h _— — — caryophyllacea Smith, = _- 4 _ — — minor Smith, = — 14, 23 — — — Picridis F. Schuitz, — — 25 -- _— — Hederae Duby, — 1 3 = ie eS Lathraea Squamaria Z., on OK — — — = = ScROPHULARIACEAR. Verbascum Thapsus Z., x at — = = ae Lychnitis Z., x = — = es ee nigrum L., — 12 — — = ea Erinus alpinus L., x = = — _— aa Digitalis purpurea L., x — = — = a Antirrhinum majus L., x — — == = = Linaria Cymbalaria Z., — 12 geo = = * Elatine M://, x 3 J eat as ees spuria Mill., x = = ak = = minor Desf., = 1, 12 a2 a aie pie repens Mill., = 3 oe oe —_ = purpurea L., = 12 pois = eae 3 Scrophularia nodosa Z., x == = = =e * aquatica L., x — eae — = * umbrosa Dwm., on SK = = = = eae Limosella aquatica L., x as = = = = Melampyrum pratense Z., SG ak = = a = eH sylvaticum L., 4 = = = ome a Pedicularis palustris Z., = _ = Bs 1¢ 1-6 m sylvatica L., Sy Se — = — = pas Rhinanthus Crista-galli Z., — — — 2 — 6 +m. (var.) Lasiopera viscosa Hoffm., x = = = = ee Euphrasia officinalis Z., x = = — -- — salisburgensis Funck, . x = a= = — = Prareger—The Buoyancy of the Seeds of some Britannic Plants. 37 TABLE OF SEED-BUOYANCY—continued. Seeds all sunk in less than Guppyie = results. * One Hours Days Weeks a Minute. | (1 to 24). | (1 to 7). | (1 to 4). | Months. || 0-7 days. Odontites rubra Gilid., ‘ — 12, 12 — — = * Veronica scutellata Z., Chamaedrys Z., montana Z., x x x officinalis Z., A ‘ A x = = = mae one serpyllifolia Z., x arvensis L., x peregrina Z., x agrestis Z., . : 0 eX — — = _ * Buxbaumii Zen., a 3 x — — = = = hederifolia Z., . 5 a x — = == = ie LaBIaTAE. Mentha longifolia Huds. .. . x see = = oT He for) On BiH nie De | | | pubescens Wiild., 5 : — — gentilis Z., 3 0 0 — — i arvensis Z., 5 A 5 —_— = Pulegium Z., . : 5 x — ee | - on + em bo ae 8 Lycopus europaeus L., 3 ; = = Salvia Verbenaca L., : : x = — = = * pratensis L., a i 3 = a 6 ae as Lar Origanum vulgare Z., : 6 — _ 1 — — = Thymus Serpyllum L., 0 F x = = — — = Chamaedrys F7., 4 7 = 12 = — = wees Clinopodium Acinos 0. Kuntze | = — — 24 = = = (fruit), ” (seed), — 12 te nes ae sl vulgare Z., : : gill Bop = — = = a Melissa officinalis Z., . x Scutellaria minor Huds. . ; x = — — — — Prunella vulgaris L., x Nepeta hederacea Z’rev., x Lamium amplexicule Z., . 5 | Sp SK a = = =: pee molucellifolium F7., . 3 x = _ _— — — hybridum Vid/., : : x — — — — ae SCIENT. PROC. R.D.S., VOL. XIV., NO, Il. F 38 Scientific Proceedings, Royal Dublin Society. TABLE OF SEED-BUOYANCY—continued. Name. Seeds all sunk in less than One Minute. Hours. Days (1 to 24). | (1 to 7). Weeks (1 to 4). Months. Guppy’s results. * 0-7 days. Galeopsis Ladanum Z., Tetrahit Z., Stachys officinalis Franch., - sylvatica L., palustris L., arvensis L., Marrubium vulgare L., Teucrium Scorodonia Z., Ajuga Chamaepitys Schreb., VERBENACEAE. Verbena officinalis Z., PLUMBAGINACEAE. Statice Armeria Z., PLANTAGINACEAE. Plantago Coronopus Z., maritima Z., lanceolata L., media L., major L., ILLECEBRACEAE. Corrigiola littoralis Z., CHENOPODIACEAE. Suaeda maritima Duwm., Salsola Kali Z. (seed), p (dry fruit), Chenopodium album Z., murale Z., hybridum Z., rubrum Z., Bonus-Henricus Z., Salicornia radicans Sm., Atriplex patula Z., x Xe OG eX | 1-4 w. 6-12 m. PrancER— The Buoyancy of the Seeds of some Britannie Plants. TABLE OF SBEED-BUOYANCY— continued. 39 Name. Seeds all sunk in less than One Minute. Hours (1 to 24). Days (1 to 7). Weeks (1 to 4). Months. Y Guppy’s results. 0-7 days. PoLYGONACEAE. Rumex conglomeratus Mur, sanguineus L., pulcher L., obtusifolius L., crispus Z., . Acetosa L., Acetosella L., Oxyria digyna Hill, Polygonum yiviparum ZL. (bulbils), lapathifolium Z., maculatum Babd., Persicaria Z., Hydropiper Z., minus Huds., aviculare Z., Roberti Lois. , Convolvulus Z., . Fagopyrum esculentum Moench, ELAEAGNACEAE. Hippophae Rhamnoides Z. (seeds), EMPETRACEAE. Empetrum nigrum L. (fresh fruit), an (dry fruit), <5 (seed), KuPHORBIACEAE. Buxus sempervivens L., Euphorbia Helioscopia Z., . stricta Z., hiberna Z., Esula Z., Paralias L., portlandica L., 124m. F2 40 TABLE OF SEED-BUOYANCY—continued. Scientific Proceedings, Royal Dublin Society. Name. Seeds all sunk in less than One Minute. Weeks (1 to 4). Hours (1 to 24). Days (1 to 7). Euphorbia Peplus Z., exigua L., . Lathyrus Z., Mercurialis perennis Z., annua Z., CALUITRICHACEAE. Callitriche autumnalis Z., . UrtTICACEAE. Parietaria ramiflora Moench, Urtica urens Z., Humulus Lupulus Z., ULMACEAE. Ulmus campestris Z. (dry fruit), . AMENTACEAE. Salix pentandra L., repens Z., . reticulata L., Myrica Gale L., Betula verrucosa Hhrh., alba L., ConIFERAe. Taxus baccata L. (fresh fruit), 55 (seed), Juniperus communis ZL. (dry fruit), Pinus sylvestris L., TyPHACEAE. Typha latifolia Z., angustifolia Z., Sparganium erectum Z., minimum F’., ARACEAE, Arum maculatum Z. (seed), x Months. Guppy’s results. * 0-7 days. Prarcer—The Buoyancy of the Seeds of some Britannic Plants. 4j TABLE OF SEED-BUOYANCY—continwed. Name. Seeds all sunk in less than One | Minute. Hours (1 to 24). Days (1 to 7). Weeks (1 to 4). Months. Guppy’s results. 0-7 days. NATIADACEAE. Potamogeton polygonifolius Powrr.. coloratus Hornem., alpinus Bailb., pusillus Z., interruptus it., filiformis Pers., Ruppia rostellata Hoch, Triglochin maritimum JZ., . palustre Z., ALISMACEAE. Alisma Plantago Z., Sagittaria sagittifolia L. (fresh fruit- head), 95 (dry seed), . ORCHIDACEAE. Orchis maculata Z., incarnata L., Gymnadenia conopsea Brown, albida Rich., Neotinea intacta Leich., Ophrys apifera Huds., Neottia Nidus-avis Rich., . . Epipactis longifolia AJlioni, Cephalanthera longifolia Fritsch, Tracer. Sisyrinchium angustifolium Mi//., californicum dit., Tris Pseudacorus Z., Romulea Columnae 8. § 1., AMARYLLIDACEAE. Leucojum aestivum Z., = = w (oS Ll ee bw wo He ne te oe for) 42 Scientific Proceedings, Royal Dublin Society. TABLE OF SEKD-BUOYANCY—continued. Seeds all sunk in less than “Grrprs Name. l Beats. sittin, Goa, fies 4). as B, Months. || 057 days: LILIACEAE. Asparagus officinalis Z. (seeds), . x — = a= — cs Paris quadrifolia Z., x _— = = — Bass Conyallaria majalis Z. (fresh fruit), x - — = = ae ah (dry seed), x — = = = ass Polygonatum multiflorum A//. (fresh fruit), x = = = see sath op (dry seed) . < = a a = esi Scilla verna Huds., x = te — ze a Allium Babingtonii Borr., . 5 = 12 = = — as vineale Z. (bulbils), . : x _ = — — ae carinatum ZL. (bulbils), 0 —_— — 1 — = eS ursinum ZL. 5 8 9 — ] = = = ae Colchicum autumnale Z., . , sep SK — = a= ae ete Tofieldia palustris Huds.,. : —_ — 2 = ee a Narthecium ossifragum Huds., . _ 12 — _— — i JUNCACEAR. Juncus acutus Z., x = 1} = = ae effusus Z., x = = = wet * inflexus L., 6 : : x = _ = — * balticus Wiild., x = = = = as capitatus Weigel, x = = = —_ | = articulatus Z., . : ‘ SX — = — =e | * acutiflorus Hhrh., 0 : x — = = = ise squarrosus Z., . A 5 x = = ai ie * Gerardi Lois., . x — = = =e mie bufonius L., ° : E || x 7 | x 0-7 Atropa Belladonna, il; —_— | x = Hippophae Rhamnoides, . : _ = | x = Empetrum nigrum, 9 é x 7 7 — Taxus baccata, x x x | 0-7 Juniperus communis, ‘ ; — Pil, DES} | — — Arum maculatum, . x — | x 0-7 Convallaria majalis, c : x = | x = Polygonatum multifiorum, x x | x is It will be seen that while the majority of these fleshy fruits sink at once, their buoyancy is usually increased, sometimes very largely, by drying. Taking the seventeen plants in which the buoyancy of both fresh and dried fruit was observed, we find that the result of drying is to increase the buoyancy from an average of 2°3 days to an average of 12:9 days. While the fresh fruit of only four of these seventeen plants was buoyant, the dried fruit of all but five of them floated for some time. In the case of Berbers vulgaris and of Rhamnus Frangula, the effect of drying was to diminish the buoyancy. When dried fruits, such as rose-hips, are placed in fresh water, and air is not excluded, fermentation often sets in, and the fruit, either before or after sinking, becomes inflated with gases, and floats buoyantly until disintegration sets in ; what the result of this is on the vitality of the seeds was not tested. The seeds of a large majority have no buoyancy, even when dried. All but twelve out of the thirty-six sank at once, and of these twelve only lew Aquifolium, Cornus suecica, and Empetrum nigrum floated for a week or ten days. VARIABILITY OF BUOYANCY IN SEEDS OF THE SAME SPECIES. In any batch of seed—eyen in a group of seeds taken from the same seed- vessel—a considerable variation in buoyancy exists. In the case of those that sink at once, the lightest seeds will take twice, or three times, or even four times as long to reach the bottom as the heaviest seeds will. Similarly, in those which float, the most buoyant seeds will sometimes float up to four times as long as the least buoyant. On the whole, to obtain the average PRAEGER—The Buoyancy of the Seeds of some Britannic Plants. 59 buoyancy of the seeds given in my list, one might perhaps divide my figures by three. But while this variability exists among the individual seeds, it was found that if any batch of seed be divided, its sections behave very uniformly as regards maximum and minimum buoyancy, showing that the test employed is a satisfactory one. At the same time, batches of seed collected in different places at different times occasionally displayed, when compared, a difference in their buoyancy far exceeding the difference observed within any one batch. While some of the discrepancies between Guppy’s results and my own, as shown in the table, are possibly explicable by different conditions of experiment, the same cannot apply to different batches tested by myself under similar conditions. The most striking cases of variability of buoyancy, taken from the table, are listed below :— Ranunculus sceleratus—38} days. (Guppy, 6-12 months.) R. repens—3} days. (Guppy, 6-12 months.) Radicula palustris—3 hours, 12 days. Raphanus Raphanistrum (dry fruit)—5 days, 4 months. Comarum palustre—2 months, 15+ months. (Guppy, 12+ months.) Haloscias scoticum—54 days, 24 months. Bidens cernua—3 weeks. (Guppy, 6-12 months.) Helminthia echioides—12 hours, 1 day, 15+ months. (Guppy, 0-7 days.) Rhinanthus Crista-Gali—2 weeks. (Guppy, 6+ months.) Lycopus europaeus—24 days, 15+ months. (Guppy, 12+ months.) Mentha pubescens—64 days. (Guppy, 6+ months.) Atriplex patula—sinks at once. (Guppy, 6+ months.) Euphorbia Paralias—4 days. (Guppy, 1-6 months.) Potamogeton polygonifolius—13 day. (Guppy, 6-12 months.) Sagittaria sagittifolia—1 week. (Guppy, 6+ months.) Tris Pseud-acorus—33 weeks. (Guppy, 12+ months.) Sparganium erectum—1 week, 15+ months. (Guppy, 12+ months.) Epipactis longifolia—1 month, 15+ months. ' Blysmus rufus—1 week. (Guppy, 1-6 months.) Carex paniculata—4 weeks. (Guppy, 12+ months.) C. elata—2 months, 9 months, C. panicea—2 days, 15+ months. C. paradoza—s days, 15+ months. C, vesicaria—10 days, 42 days. 60 Scientific Proceedings, Royal Dublin Society. Iam not prepared to account for these cases of variability, nor to say how many of the discrepancies will be reduced or ruled out by further experiments on the species in question. Some of them may be due to immature or unsound seed (though trouble was taken to eliminate this source of error). But, as recognized by Guppy, considerable variability does exist in certain species. To determine its limits and its causes, the experiments on the variable species would have to be considerably extended. The fact that Guppy’s buoyancy periods are usually greater than mine suggests that the difference may be due to his (presumably) using salt water, while my tests were mostly made in fresh water. But several of my batches, tested in salt water, gave results differing but slightly from the fresh-water results. BUOYANCY OF FRUITING BRANCHES. It is evident that, even if the seeds of a species sink at once, wide dispersal may still be effected if branches or crowns with fruit attached possess a considerable power of floating. This was pointed out long ago by Darwin. Accidents of one sort or another—storms, the subsidence of over- hanging banks, the trampling of animals—occasionally precipitate plants or portions of them into rivers. ‘he buoyancy of branches or fruiting crowns, both fresh and after thorough drying, was tested in the case of a few plants of different habit, with the result shown below. In the table (in which the numerals represent days) the buoyancy of the seeds, and of fresh and dry fruit where a succulent fruit occurred, is added for comparison wherever the information was available. 61 PraneeR—The Buoyancy of the Seeds of some Britannic Plants. Brancu. Srrp.! Fruit. Fresh. Dry. — Fresh. Dry. Hypericum elatum, 4 + 1 — = Tlex Aquifolium, 14 4 103 2 — Sarothamnus scoparius, 1 1 0 — — Alchemilla alpina, . 3 25 23 — = Dryas octopetala, 3 4 = 1 _— Rosa spinosissima, . 1 43 0 45 — canina, il 4 3 0 = eglanteria, 12 14 5 — — Crataegus Oxyacantha, 5 6 0 14 21 Sedum Telephium, . 7 63 2 _ = Saxifraga umbrosa, 40 3 0 — = Geum, . é 1 1 0 — — Viscum album, 0 0 0 0 z Artemisia maritima, 4 4 9 — = Achillea Millefolium, 3 4 1 =_ = Daboecia cantabrica, 2 4 ae = = Erica mediterranea, 135 63 ie = = vagans, 6 ay 34 = = ciliaris, 5 4 _— = =a Tetralix, . 3 4 0 = = Mackaii, . 3h 4 — = = Calluna vulgaris, 5 4 0 = ar Arbutus Unedo, 0 1 0 0 Limonium binervesum, 3 2 — = = Ligustrum vulgare, | 1 3 0 0 | = Solanum Dulcamara, 1 ie 0 0 = Antirrhinum majus, 15 10 0 = = Euphorbia Peplus, . | 2 dy 0 = a Taxus baccata, | 2 4 0 0 — It will be seen that among these 29 plants, which include repre- sentatives of 15 different Natural Orders, and also plants of very different growth—herbs, shrubs, and trees—the effect of using branches } Or dry indehiscent fruit. SCIENT. PROC. R.D.S., VOL. XIV., NO. II. 62 Scientific Proceedings, Royal Dublin Society. instead of seeds as the dispersal-unit is to increase materially the buoyancy ; while the seeds of 14 of the 29 plants sink at once (probably more than 14, as information is not forthcoming with reference to four of the species), in the case of branches absence of buoyancy occurs in only 2 species when fresh, and 1 species when dry, and the average buoyancy of the branches, whether fresh or dried, is considerably higher than that of the seeds. So that this exceptional means of dispersal tends towards a wider distribution by water. As regards a second point—the buoyancy of dried branches as compared with fresh ones—it is seen that the effect of drying is usually (in 14 cases) to inerease to quite a slight extent their power of floating. In many (10) other cases drying actually diminishes buoyancy, sometimes to a great extent. ‘Two remarkable instances of this kind are displayed by Sazifraga umbrosa and Erica mediterranea. In the case of S. umbrosa I tested several varieties of the species. While some sank in from 14 to 6 days when fresh, two others—a native and a garden form respectively—remained afloat for periods of 25 and 40 days. The same specimens thoroughly dried sank in a few days. As regards Erica mediterranea, its buoyancy depends largely (as in the case of other heaths) on air imprisoned in the withered corollas. Probably under natural conditions of dispersal, where the branches were being tossed about in a river or in the sea, the air would be expelled from or dissolved out of the corollas more rapidly than under the comparatively tranquil conditions of an experimental tank. Even leaving out of account these two exceptional species (whose inclusion would make the average buoyancy of the fresh branches considerably greater than that of the dried branches), we still find that the average buoyancy of the remainder is but very slightly increased by drying, the average time of floating of the fresh branches being 3:9 days, and of the dried branches 4-2 days. It will be noted that this result is much less favourable to the idea of increase of dispersal-efliciency by drying than that obtained by Darwin from a similar series of experiments, and quoted in the ‘“ Origin of Species,” chapter xii. Darwin does not givea list of the plants he experimented upon; and inmy own case the number of species tested is too small to permit of any generalization. ON Zan © jy te THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. Vol. XIV. (N.S.), No. 4. JULY, 1918. ON A VIOLET COLOURING-MATTER AND ITS PRODUCTION BY A CERTAIN BACTERIUM. BY W. J. HARTLEY, B.A. [ COMMUNICATED BY SIR WALTER N. HARTLEY, F.R.S. | [Authors alone are responsible for all opinions expressed in their Communications. } DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY, LEINSTER HOUSE, DUBLIN. WILLIAMS AND NORGATE, 14, HENRJETTA STREET, COVENT GARDEN, LONDON, W.C. 1913. Aesonian IMStituge J on \ /S Price Sixpence. Roval Bublin Society. ee a FOUNDED, A.D. 1731. INCORPORATED, 1749. ~~ EVENING SCIENTIFIC MEETINGS. Tuer Scientific Meetings of the Society are held alternately at 4.30 pm. and 8 p.m. on the third Tuesday of every month of the Session (November to June). Authors desiring to read Papers before the Society are requested to forward their Communications to the Registrar of the Royal Dublin Society at least ten Jays prior to each Meeting, as no Paper can be set down for reading until examined and approved by the Science Committee. The copyright of Papers read becomes the property of the Society, and such as are considered suitable for the purpose will be printed with the least possible delay. Authors are requested to hand in their MS. and necessary Illustrations in a complete form, and ready for transmission to the Editor. fies IVE ON A VIOLET COLOURING-MATTER AND ITS PRODUCTION BY A CERTAIN BACTERIUM. By W. J. HARTLEY, B.A. [ COMMUNICATED BY SIR WALTER N. HARTLEY, F.R.S. | (Read May 20; Published Juny 11, 1913.] In the course of an examination of the waters used in certain Irish creameries a sample was examined in which a chromogenic bacterium of a bright violet colour was found. The sample was delivered at the Royal College of Science, Dublin, on April 17th, 1912, from a creamery in County Wexford. On the same day 0:1 and 1:0 c.c. were plated out in gelatine in the usual manner, and incubated in the dark at 20°C.; on April 23rd it was noticed that two colonies had a distinctly blue appearance, and sub-cultures were made from one of them. The cultural characters were found to be variable. For instance, gelatine was sometimes liquefied in seven, sometimes in fourteen, and sometimes not in twenty-one days. The thermal death-point after exposure to moist heat for one minute is apparently between 50° and 55°C. Sub-cultures from a culture previously heated to 50°C. produce little colour and liquefy rapidly; otherwise lique- faction rarely or never precedes colour-production. Colour-production varies curiously. Agar colonies show colour in concentric rings. Agar streak-cultures usually produce colour on the margin, spreading inwards and intensifying till the tenth day. Sometimes colour is not produced for twenty-one days, and liquefaction may then vecur. Colour was not produced unless more water were present than was sufficient for the growth of the organism. The addition of sterile water to a well-grown, colourless, partly desiccated culture seventy-two days old, was followed by colour and liquefaction in forty-eight hours. Experiments to find whether the colour is excreted or contained in the organism were inconclusive. With the exception of the statement of Macé,’ 1 Macé, Traité de Bactériologie, 1897, pp. 849-858, SCIENT. PROC. R.D.S., VOL, XIV., NO. IV, K 64 Scientifie Proceedings, Royal Dublin Society. that B. violaceus produces spores, the cultural characteristics of this organism, owing to their variation, agree with his description of both B. violaceus and B. tanthinus. In order to test the effect of media on colour-production, an inorganic food-basis solution was made up as follows :— 0:5 grm. NaCl. 10 erm. KH,PO,. 05 grm. MegSQ,. Trace of CaCl.. 0:008 MegCO,. Distilled water to 1 litre. This solution was divided into five parts, to each of which was added. 1-5 per cent. of agar-agar as follows :— No. 1. Inorganic food-basis with agar. », 2. Same as No. 1, with two per cent. lactose. 9) 9. mn a ,, two per cent. starch. mp “5 5 ,, two per cent. urea. Be a » 5, two per cent. peptone. Slope cultures of the bacillus were made on all these media and incubated at 20°C. Slight growth occurred on Nos. 1 and 4; better growth on Nos. 2 and 3; and good growth and colour were found on No. 5 (the peptone) in about five or six days. Cultures were made in a 0:29 per cent. potassium nitrate solution free from nitrites; and after five days’ incubation the medium was found to contain nitrites, showing the reduction of nitrates by the bacillus. Preparation and Separation of the Pigment. Slices of potato were sterilized in Petri dishes, and inoculated by quickly pouring over them an emulsion of bacteria. This emulsion was obtained by pouring about 10 ce. of sterile water into a well-coloured culture of the bacillus on an agar slope. After four or five days’ incubation at 20°, the potatoes appeared to be covered with a violet dew or “ shagreenlike” growth; and on the eighth, ninth, or tenth day the growth appeared more blue and slimy, the slime being due in part to the partial decomposition of the potato. The growth was then lightly scraped off the potato with a spatula and placed in a ‘Sohxlet thimble.” The colour was extracted by distilling absolute alcohol on to the growth until no more colour came over with the alcohol in the siphon tube, ‘The solution was then placed ina boiling tube and allowed Hartiey—On « Violet Colouring-Matter, &¢. 65 to stand for two or three days, and afterwards decanted or pipetted off, leaving about 10 oc. of solution. This last part sometimes contained a deposit of dead bacteria and other matter which had siphoned over. A part of the clear violet solution was now tested for starch, a possible impurity from the potato, with a negative result. ‘he solution was then evaporated down to dryness, partly on a water-bath and partly in vacuo ; when dry it was a dark blue, almost black in mass, amorphous solid. It dissolved readily in cold alcohol, giving a violet solution, and in ether a purple solution, as also with chloroform. A volume of 1:5 c.c. was placed in each of the ten tubes, and tested with the following reagents :— To No. 1 was added 0°5 c.c. of Normal KOH. The colour changed to blue, to green, and then to yellow. To No. 2 was added 0:5 ¢.c. Na,CO; Normal. The colour changed to a dark blue. To No. 3 was added 0:1 c.c. ‘‘ Concentrated” H,SO,. The colour changed to green. To No. 4 was added 0°83 cc. ‘ Concentrated ” H,SO,. The colour changed to yellow. To No. 5 was added 0:2 cc. HNO; “ Concentrated.” The colour changed to yellow. To No. 6 were added 2 drops of strong Ammonia. The solution was immediately bleached ; the addition of acetic acid failed to restore any colour. With dilute Ammonia it turned green before bleaching. To No. 7 was added adrop of bromine water. Colour instantly destroyed. To No. 8 was added 0:5 cc. H,O, An opalescent blue, possibly due to partial precipitation of the colouring matter by water. To No. 9 was added 0°5 c.c. SnCl,, Gives a colourless solution on standing. To No. 10 was added 0°5 c.c. ether. Gives a purple tinge to the alcoholic solution. The pigment will act as an indicator to acids if sufficient alkali be present to turn the violet solution blue. The addition of acids turns it green, as, for example, weak hydrochloric acid. If an ethereal chloroform or alcohol solution be evaporated from a test-tube, the dissolved pigment will precipitate on the glass and show the same colour as the solution from which it pre- cipitated. Some 20 c.c. of the alcoholic solution were poured through a column of precipitated chalk, in the hope that if two pigments were present they would separate, but this did not occur. In order to test the dyeing properties of the colouring-matter, some 20 c.c, of the alcoholic solution (containing 0:02 grms. solid) were placed in a K 2 66 Scientific Proceedings, Royal Dublin Society. flask connected with a reflux condenser. Some pieces of linen, wool, silk, and cotton were washed with soap and water, and placed in running water over night, when small dry portions were added to the solution and boiled for two hours. On removal it was found that neither the wool, silk, nor cotton was changed in colour; but the linen when laid on white paper was faintly blue. This test with silk- and wool-fibres serves to distinguish the colour from that of a solution of aniline violet. The colour reactions with acids and alkalis are also different. Some 5:0 cc. of an alcoholic solution containing 0-005 grm. of solid were placed in an air-tight glass weighing-bottle. This was placed in a window for twenty-four days, during which time it was not exposed to more than twelve hours’ direct sunlight, and at the end of the period the solution was almost colourless; only a faint trace of red remained. The Absorption Spectrum of the Colouring-Matter. A portion of the first alcoholic solution was evaporated partly on a water- bath and partly i vacuo, and repeatedly weighed till constant, the weight of the colouring-matter being 0:022 grm. A preliminary examination was made with a miscrospectroscope by Zeiss, conveniently fitted with a scale of wave-lengths. A. glass tube, 27 m.m. long by 10 mm. internal diameter, was cemented vertically to a thin glass microscope-slide, and in this the solution was placed. Thicknesses of solution greater than 10 mm. showed transmission of the blue, indigo, and a portion of the violet rays, or from a little beyond the solar line F to a point half way between G and H. There was total absorption of the red rays from A to beyond &; but a narrow band of bright red light with its centre about C’ was transmitted. Small thicknesses showed transmission of the bright red rays from A 670 to A 640, and absorption from about A 640 to 490, the rays beyond F being transmitted. A more precise examination of the same solution was made with one of Hilger’s fixed deviation wave-length spectroscopes, illumination being by sunlight directed on to the slit by a heliostat. No rays were transmitted through a thickness of 25mm.; through smaller thicknesses, the measurements resembled those obtained with the Zeiss instrument and, stated generally, the rays less refrangible than A 6700 were absorbed ; the bright red rays from about A 6670 to about A 6240 were fully transmitted. The rays from 6100 to near #’(A 4900) were absorbed; but a feeble transmission near the green 4' 4? group to beyond F was seen, with a complete transmission from A 4900 to’ 4090. The variations in the sunlight on the Harriey—On a Violet Colouring-Matter, &c. 67 few occasions when it was available made it difficult to measure accurately ; and therefore it was decided to rely on the photographs of the absorption- spectra, which were taken in the following manner :-— A weighed quantity of the dried pigment, 0°022 grm., was dissolved in 5cc. of “absolute” alcohol and successively diluted to 10, 15, 20, 40, 80, and 160 cc. (see Curve). (The solid was not entirely dissolved by 5c.c. of cold alcohol, but was completely dissolved by 10 c.c.) The spectrum of the alcohol was photographed through the same thickness (5mm.). It transmitted all the rays to A 2495 strongly, and feebly to 2196. The source of light was the continuous rays and metallic lines emitted by a condensed spark passing between electrodes, one of which was composed of an alloy of cadmium, 15 per cent. tin, 85 per cent.; the other cadmium, 15 per cent. lead, 85 per cent. The cell was of glass with quartz ends, giving a layer of liquid 5mm. thick. The instrument was a quartz spectrograph, photographing lines, from 47500 to X 2145 in focus on one plate, and extending to a length of more than 100 mm. The plates were Wratten and Wainwright’s panchromatic spectrum plates. The rays from the spark were condensed by a large quartz lens on the cell, which was placed so that a sharp image of the spark was focussed on the slit of the instrument, the exposure for each photograph being one minute. [Diagram anv ABLES. 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