as habitat-forms of one species, the differences in structure being attributed to the influence of water. In this as in many other recently published papers it is satisfactory to find that authors are now paying more attention than formerly to the significance of structural features as indices of climate and habitat. Mr. Sahni's critical morphological study of the branching of the leaf-trace in certain Carboniferous genera of ferns114 throws light on some previously misunderstood anatomical features and illustrates the value of the application of broad philosophical generalizations based on intensive study of allied forms. Miss Holden's account of the anatomy of two Paleozoic Cardaitalean stems from India;15 placed in the genus Dadoxylon, supply welcome information on the structure of plants belonging to the Glossopteris flora: the occurrence of well marked rings of growth in the wood of both species is a fact of special interest from the point of view of the climatic conditions under which the plants of the southern flora flourished. A report of a British Association Committee published in 1917 summarizes opinions on the vexed question of the classification1o of the older rocks of Gondwana land in which plants of the Glossopteris flora are preserved. Researches of both scientific and economic interest into the composition and mode of origin of coal have in recent years attracted the attention of several workers. The most important piece of work of this kind is that by Dr. Stopes and Dr. Wheeler,17 a happy combination of expert botanical and chemical knowledge. The authors begin by defining ordinary coal as a compact, stratified mass of mummified plants free from all save a very low percentage of other matter," that is practically a deposit of plants alone. It is rightly claimed that too little attention has hitherto been paid to research following logical deductions from our knowledge of the chemical 66 14 Ibid., Vol. XXXII., p. 369, 1918. 15 Annals of Botany, Vol. XXXI., p. 315, 1917. 16 British Assoc. Report, 1917, p. 106. 17 Monograph on the Constitution of Coal. Dpt. Scientific and Industrial Research, London, 1918. composition of plants. The authors deal with modes of accumulation of coal-forming vegetable material action of the solvents on coal, the effect of heat, distillation at different temperatures, microscopic evidence bearing on the constitution of coal derived both from the coal itself and from the petrified tissues preserved in the calcareous nodules of certain coal seams. A very useful bibliography is appended. Mr. Lomax18 has continued his microscopical analysis of coal seams and discusses the part played by different plants and parts of plants in the composition of coal. Similarly Mr. Hickling,19 who writes on the micropetrology of coal, reviews previous work and gives the results of original observations; he attributes differences in coal rather to the result of varying degrees or varying modes of alteration than to differences in the nature of the original constituents. 3. Mesozoic Plants.-Dr. Arber's memoir, published shortly before his death, on the older Mesozoic floras of New Zealand,20 is a particularly welcome contribution to our knowledge of the little known botanical history of that country. He deals with TriassicRhætic, Jurassic and Cretaceous plants. The author shows that no Palæozoic flora has so far been discovered: the absence of any undoubted examples of the common southern hemisphere genus Glossopteris leads him to express the view that New Zealand did not form part of that extensive continent known as Gondwana land in the Permo-Carboniferous period. An account is given of a remarkable petrified forest at Waikawa, Southland, consisting chiefly of some conifers and wellpreserved osmundaceous stems. Dr. Arber's work clears up many obscure points and corrects erroneous statements by previous authors. Important contributions have been made to our knowledge of Jurassic plants, notably the description of a new genus, Williamsoniella, 18 Trans. Instit. Mining Engineers, Vol. L., Pt. I., p. 127, 1915. 19 Ibid., Vol. LIII., Pt. III., p. 137, 1917. 20 New Zealand Geol. Survey, Paleontological Bulletin No. 6, Wellington, 1917. of Cycadophyta by Mr. Hamshaw Thomas21 (now Captain Thomas) founded on material collected by him at Gristhorpe bay on the Yorkshire coast. This genus possessed fertile shoots bearing small ovules and interseminal scales crowded on a pyriform axis and surrounded at the base by a whorl of microsporophylls each bearing 5-6 synangia. The bisexual shoots were almost certainly borne in the forks of a slender dichotomously branched stem like that of Wielandiella, and there are good grounds for regarding the supposed fern leaves known as Tacniopteris vittata as the foliage of this Bennettitalean plant. Mr. Thomas's discovery22 of a bed of mummified plant remains in the Lower Estuarine series at Roseberry Topping, Yorkshire, enabled him to investigate minutely the epidermal characters of the problematical genus Thinnfeldia; he believes that the fragments of leaves and twigs of which the deposit is mainly composed were borne on trees, an interesting suggestion at variance with previous views on the nature of the genus. This author also describes a Yorkshire specimen of Williamsonia23 in the Paris Museum which is probably the male flower of Williamsonia gigas. Miss Holden's account of a new type of coniferous stem, Metacedroxylon24 from the Corallian of Sutherland, Scotland, adds another to an already long list of Mesozoic types exhibiting a mixture of Abietineous anatomical characters. An examination by the same author25 of impressions of Wealden fronds previously referred to the genus Cycadites and believed to be closely allied to the recent Cycas shows that they should be transferred to Pseudocycas. A paper by Mr. Clement Reid and Mr. Grove26 on Characes from the Purbeck of Dorset gives a preliminary account of their researches into the fossil representatives 21 Phil. Trans. R. Soc., Vol. 207, Series B, p. 113, 1915. 22 The Naturalist, January 1, 1915, p. 7. 23 Proc. Cambridge Phil. Soc., Vol. XVIII., Pt. III., p. 105, 1915. 24 New Phytologist, Vol. XIV., p. 205, 1915. 26 Proc. R. Soc., Series B, Vol. 89, p. 252, 1916. of this neglected family; they describe a new genus, Clavator, characterized by club-like nodes on the stem and by other characters. Dr. Marie Stopes has instituted a new genus, Planoxylon,27 for a Cretaceous New Zealand coniferous stem combining Abietineous and Araucarian features; she suggests that this generalized type points to the existence in the southern hemisphere of an extinct group of conifers of unexpectedly Abietineous affinities. The same author28 describes the structure of the first specimens of roots of Bennettites so far discovered. Several papers by Dr. Ellis29 deal with fossil fungi and include descriptions based on characters of doubtful value of some supposed new species from Jurassic and Cretaceous rocks; the author also discusses the rôle of microorganisms in the formation of ironstones. 4. Tertiary and Pleistocene Plants.-Mr. Dutt's careful account of Pityostrobus macrocephalus,30 believed to be allied to Pinus excelsa, from the Lower Eocene of the London Basin is an interesting morphological contribution and reveals the occurrence of unusual features in this well-preserved Abietineous cone which have been overlooked by previous authors. Papers by Mr. Clement Reid31 and by Professor Marr and Miss Gardner32 extend our knowledge of the Arctic Pleistocene flora of England and of the conditions under which the plants grew. In his "Notes on Calamopitys "33 Dr. Scott deals with the same fulness and critical insight with the known species of this Lower Carboniferous genus, a type showing certain affinities to Lyginopteris and Heterangium. We have unfortunately no knowledge of its reproductive organs. The paper contains 27 Annals of Botany, Vol. XXX., p. 111, 1916. 28 Ibid., Vol. XXXI., p. 257, 1917. 29 Proc. R. Soc. Edinburgh, Vol. XXXV., Pt. I., p. 110, 1915; Knowledge, Vol. XXXIX., p. 73, 1916; Geol. Mag., Vol. IV., p. 102, 1917. 30 Annals of Botany, Vol. XXX., p. 529, 1916. 31 Quar. Jour. Geol. Soc., Vol. LXXI., p. 155, 1917. 32 Geol. Mag., Vol. III., p. 339, 1916. 33 Jour. Linn. Soc., Vol. XLIV., p. 205, 1918. SPECIAL ARTICLES THE BLACK CHAFF OF WHEAT THE continued prevalence of black chaff of wheat in the United States makes it desirable to have a Latin-scientific name for the bacterial organism causing it. This organism resembles Bacterium translucens (see Journal of Agricultural Research, Vol. XI., p. 625, 1917), cause of the bacterial blight of barley. In cross inoculations on the leaves of seedling plants the barley organism on wheat has proved either non-infectious or has produced small non-typical lesions. On the other hand, inoculation experiments have shown that the wheat organism is practically as pathogenic on barley as it is on wheat and the lesions so produced on barley are indistinguishable from those produced by the barley organism itself. There also appear to be minor cultural differences. It is suggested, therefore, that for the present, at least, the wheat organism be distinguished as Bacterium translucens var. undulosum with, in general, the characteristics already given for the species: Var, undulosum nov. var., cause of the black chaff disease of wheat, produces yellow or translucent stripes on leaves, water-soaked or black stripes on culms, and longitudinal, more or less sunken, dark stripes or spots on the glumes. In moist weather the bacteria often ooze to the surface of the diseased spots or stripes as tiny beads or drops, drying yellowish. From sections of diseased leaves or glumes mounted in water they ooze in enormous numbers (like smoke out of a chimney) making the fluid cloudy. This organism attacks also the kernels, especially at the base causing them to be shrunken and honeycombed with bacterial pockets, but even when the kernels are not attacked their surface is liable to be infected from the diseased glumes. When the disease appears early and is severe the heads are dwarfed. Surface colonies on thin-sown agar plates are circular, pale yellow, smooth (like polished glass) and structureless on the surface, usually homogeneous also by direct transmitted light, but by oblique transmitted light (half-light) the interior is seen to be full of minute waves or interblending striations which persist, and which are best seen with a hand lens. It can be distinguished easily and quickly from accompanying non-parasitic yellow forms by this character alone. Slime copious and very pale yellow on potato agar; on whey agar very copious and bright chrome yellow-slime on this medium deeper yellow and less fluid than that of the barley organism. Infections have been obtained repeatedly on wheat leaves and glumes. The disease is transmitted to young seedlings by way of the wheat kernels. It occurs in all the wheat states of the Middle West. For earlier notes consult SCIENCE, N. S., Vol. XLIV., No. 1134, p. 432, 1916, the Journal of Agricultural Research, Vol. X., No. 1, 1917, and the Plant Disease Bulletin (issued by The Plant Disease Survey, Bureau of Plant Industry, U. S. Department of Agriculture), Vol. I., No. 2, 1917, and Vol. II., No. 6, 1918. ERWIN F. SMITH, L. R. JONES, C. S. REDDY THE BUFFALO MEETING OF THE The rapid determination of titanium in titaniferous iron ores: JOHN WADDELL. The ore is fused in a silver, copper or iron crucible with sodium peroxide, for about ten minutes. The crucible with the fused mass is brought into a beaker with water, and the disintegrated material dissolved in sulphuric acid. Tartaric acid is added to keep the titanium in solution. Sulphuretted hydrogen is passed through the solution. If a copper or silver crucible has been used, the precipitated sulphide is filtered off, and to the filtrate, ammonia is added and more sulphuretted hydrogen is passed. To the filtrate from the iron sulphide, sulphuric acid is added and the solution is boiled to drive off the sulphuretted hydrogen and to coagulate the sulphur. After filtration, the solution can be made up to a given volume, and an aliquot portion taken for comparison of the color produced by addition of hydrogen peroxide, with that of a standard titanium solution. Or, the titanium may be precipitated with cupferron, and the precipitate burned and weighed as titanium oxide. A standard magnetite of the Bureau of Standards containing 0.99 per cent. TiO2 was analyzed, and the results were within a few hundredths of a per cent. of that given. Concordant results were also obtained with an ore containing between thirteen and fourteen per cent. of TiO2. Fusion of the ore with borax in a platinum crucible also gave satisfactory results, the disintegration of the fused mass being however not so rapid as when sodium peroxide was used. substance from the ordinary molecular condition of the elements. On an efficiency basis this amounts to about 250 grams of nitric acid per kilowatt hour. This possible yield compares fav orably with the 134 grams obtainable from the union of oxygen and nitrogen at 4,200° A. in the purely thermal process. In practise a combination of the thermal and electrical process is used. Similarly in the formation of ozone the limiting yield is about 510 grams per kilowatt hour as compared with 80-90 grams, the best results actually obtained with an efficiency of 15-17 per cent. The calculation of the efficiency of the silent discharge process for nitrogen fixation: F. O. ANDEREGG. Oxygen combines with nitrogen in the silent discharge. The discharge evidently changes the comparatively inert molecule into a more active condition which is probably atomic. The energy required for this activation is all that is necessary for the fixation of nitrogen. The splitting up of the molecules is probably the result of electrons, which have acquired a suitable velocity by falling through a minimum potential gradient colliding with the oxygen or nitrogen molecules. To calculate this energy of activation of oxygen use may be made of the fact that ultra-violet light of a wave-length shorter than 190 uu is completely absorbed by oxygen with ozone being formed. This corresponds to a potential gradient of about 6.4 volts using the quantum theory. Then to activate one mol of oxygen requires about 146 large calories. For nitrogen the wave-lengths have not been similarly determined but the recent work of Davis and Goucher1 makes the value of 9 volts seem to be a likely one. This corresponds to 207 calories per mol. At ordinary temperatures in the silent discharge the nitric oxide first formed is oxidized not merely to tetroxide but, because of the excess of ozone, to pentoxide, requiring one more active oxygen for this step. The complete reaction for the formation of nitric acid anhydride is then 2N(207) + 20 (−146) + 02 + 0(− 73) = N2O.(+1.4) + 427.4 calories. The numbers in brackets represent the values in large calories required for the formation of the 1 Phys. Rev., 13, 1-5, 1919. PH The viscosity of casein solution-I., the effect of HARPER F. ZOLLER. The study of the viscosity of casein in alkaline solutions was taken up with the ultimate object of determining its chance relationship to the adhesiveness of such solutions. Viscosity curves of Hammarsten and Dairy Division caseins dissolved in sodium hydroxide show a maximum viscosity in the region of 9.0 PH. The slope of the curve is very precipitous on either side of the maximum. The hydrogen-ion concentration was measured both colorimetrically and electrometrically; the Clark electrode-vessel being employed for the latter determinations. A great significance is attached to the flattening of the viscosity curves immediately following the decline from the maximum. This is intimately correlated with the alkaline hydrolysis and evolution of ammonia in this zone. Solutions of casein in ammonia do not exhibit the precipitous decline from the maximum viscosity, although the maximum is in the same narrow region of PH. The observations of Sakur, Pauli, Chick and Martin and Robertson were reviewed. Periodic vibrations in gels: J. M. JOHLIN. Boiling point of liquids: F. P. SOEBEL. Basing his deductions on the assumption that at the boiling point of a liquid the vibratory energy of individual molecular constituents of the liquid and of its vapor must be equal, the author finds that the absolute temperature To of the boiling point of an absolutely pure liquid is expressible as Similar agreement is found for other vapors by inserting the correct valve for constant as long as no psolymerisation in the liquid takes place. (1) Molecular state of water vapor; (2) Vapor pressure depression equation for dilute aqueous solutions: JAMES KENDALL. Size and behavior of suspended smoke particles: R. E. WILSON. Influence exerted by antagonistic electrolytes on the electrical resistance and permeability of emulsin membranes: G. H. A. CLOWES. The exact determination of molecular weights by the boiling point method: E. M. Washburn. Solubility of strontium nitrate in anhydrous alcohol in alcohol containing small per cent. of water: C. W. FOULK. (1) Influence of the age of ferric arsenate on its peptization; (2) Syneresis of silicic acids gels: H. N. HOLMES. A study of the lowering of vapor pressure of water produced by absorbed KCI: B. F. LOVELACE, J. C. W. FRAZER, V. B. SEASE. A study of the lowering of vapor pressure of water produced by absorbed mannite: J. C. W. FRASER, B. F. LOVELACE, T. H. ROGERS. The volume and surface of the pores in charcoal and the compression of adsorbed substances: W. D. HARKINS and D. T. EWING. An electromagnetic and valence hypothesis of heterogeneous equilibrium in adsorption: W. D. HARKINS. DIVISION OF WATER, SEWERAGE AND SANITATION Robert Spurr Weston, Chairman W. W. Skinner, Secretary Determination of bromid in mineral waters and brines: W. W. SKINNER and W. F. BAUGHMAN. Colorimetric methods for the determination of bromin give satisfactory results only when small quantities of bromin are to be determined. The method proposed for the determination of bromids in the presence of chlorids is the oxidation of the bromids and removal of the liberated bromid by steam distillation or by aspiration. The method depends upon the use of chromic acid for oxidation of the bromid. Chromic acid in concentrated solution liberates bromin from bromids quantitatively at room temperature and the bromin may be removed by aspiration. It liberates only a trace of chlorin from chlorids, forming probably chromic chlorid which remains in solution. When chromic acid acts on a solution of chlorids and bromids, some chlor-bromid is formed which is removed with the bromin by aspiration. The liberated bromin and the chlorin in the first aspiration is collected in a solution of sodium sulphite and sodium carbonate, which is evaporated to dryness and again submitted to the treatment with chromic acid and aspirated the second time. The double aspiration gives very accurate results. Certain war gases and health: CHARLES BASKERVILLE. Evidence has been collected from all the chlorine producing plants and many works and arsenals where chlorine was used. Preponderating evidence favors the conclusion that chlorine exerts a preventative influence against influenza. The evidence is not conclusive, however, as contrary data were obtained from some plants. The contradictions may possibly be harmonized on the basis of concentration, the more dilute up to limits the more effective. Small amounts of bromine in the air appear to prevent influenza completely. |