382 



NATURE 



[May 19, 192 1 



upon the electrified pith ball appears to be independent 

 of the nature of its charj^e. — Dr. R. Kidston and Prof. 

 W. H. Lang : Old Red Sandstone plants, showing 

 structures from the Rhynie Chert Bed, Aberdeen- 

 shire. Part iv. : Restorations of the vascular crypto- 

 gams, and discussion of their bearing on the general 

 morphology of the Pteridophyta, and the origin 

 of the organisation of land plants. Restora- 

 tions of the four plants, Rhynia Givynne-Vaiighani, 

 R. major, Hornea Lignieri,, and Asteroxylon Mackiei, 

 are given. A few additional features, supplementary 

 to the descriptions in preceding papers of the series, 

 are described. The hemispherical projections of 

 Rhynia Gxvynne-V aughani are shown to have 

 originated underneath stomata. A comparison is 

 made between them and certain intamescences in 

 existing plants. Areas of necrosis and marked wound- 

 reactions of the tissues around them are described 

 for both species of Rhynia. The apex of a stem of 

 R. major is figured. The discussion summarises the 

 authors' views on the bearings of the facts described 

 in the Parts i.-iv. on problems in plant-morphology. 

 Part v. : The Thallophyta occurring in the jjeat-bed ; 

 the succession of the plants throughout a vertical 

 section of the bed, and the conditions of accumulation 

 and preservation of the deposit. The Thallophyta 

 found in the silicified peat are described. The most 

 abundant are fungi represented by hyphEe of the 

 mycelium, and vesicles or resting-spores borne on 

 this. With the exception of one specimen, the 

 hyphae were non-septate, and the. fungi are regarded 

 as belonging to the Phycomj'cetes. A number of 

 form-types are described ; the si:>ecies distinguished are 

 Palaeomyces Gordoni, P. Gordotii var. major, P. 

 asteroxyli, P. Horneae, P. vestita, P. Simpsorii, and 

 P. agglomeraia. The possibility of there being a 

 symbiotic (mycorrhizal) relation between certain fungi 

 and the vascular cryptogams is discussed ; there is 

 no conclusive evidence in favour of this. The majority 

 of the fungi in the Rhynie peat were certainly living 

 as saprophytes. Bacteria were doubtless present in 

 abundance, but are difficult to distinguish in the 

 granular matrix. A representative of the Schizophyta, 

 a filamentous organism with the small protoplasts pre. 

 served, is named Archaeothrix oscillatoriformls, and 

 compared with Beggiatoa and Oscillatoria among 

 existing plants. Scattered remains of an alga, the 

 vegetative structure of which presents a number ot 

 resemblances to existing Characeae, are described 

 under the name Algites (Palaconitella) cranii. Two 

 fragments belonging to an organism with the char- 

 acteristic structure of Nematophyton are described as 

 N. Taiti. The specimens show the structure of the 

 peripheral region, which in specimens previously de- 

 scribed has not been preserved. The succession of 

 the plants throughout a section of the Chert Bed as 

 exposed in situ is followed, and the conditions of 

 formation of the Rhynie deposit are discussed. On 

 grounds mainly of resemblances presented by Astero- 

 xvlon to Tharsophyton (Lycopodites) Milleri, the 

 Rhynie Chert Bed is' allocated to the Middle Old Red 

 Sandstone age. 



^ Paris. 

 Academy of Sciences, April 25. — M. Georges Lemoine 

 in the chair. — C. Guichard : Triply indeterminate 

 systems of right lines and their conjugates with 

 respect to a linear complex. — L. Cu^not : The different 

 modes of regeneration of the antennae in Carausius 

 morostis.—C. NicoUe and A. Cu6nod : New acquisi- 

 tions in the experimental study of trachoma. An 

 account of results obtained in experiments on apes 

 and rabbits. — I. Tarazona : Observation of the annular 

 eclipse of the sun on April 7, 192 1, at the astronomical 



NO. 2690, VOL. 107] 



observatory of the University of Valencia (Spain). 

 Comparison of the observed and calculated times of 

 contact. — P. Fox : Measurements of stellar parallax 

 at the Dearborn Observatory. The table giving the 

 parallax of twenty-four stars is based on photographic 

 observations with the 48-cm. equatorial.— A. Leduc : 

 The principle of equivalence and reversibility. — H. 

 Buisson and C. Fabry : The displacement of the solar 

 lines under the actiorr of the gravitational field. The 

 differences observed between the lines of the solar 

 spectrum and those of the arc in vacuum can be per- 

 fectly interpreted by the following hypotheses : the 

 pressure in the reversing layer is small, and con- 

 sequently the effect of the pressure can be neglected, 

 and the Einstein effect is the only cause of the dis- 

 placement of the lines of the solar spectrum. ^ — Mme. 

 P. Curie : The 7 radiation and the evolution of heat 

 from radium and mesothorium. The heat evolved is 

 measured by an ice calorimeter with a capillary tube, 

 one division of which corresponds to about 0-03 

 calorie. A method for the determination of the rela- 

 tive quantities of radium and mesothorium in a sealed 

 tube can be based on the calorimetric measurements, 

 and it may also be possible to determine the age of 

 the specimen by observations with time-intervals of 

 several months. — Mile. Irene Curie : The atomic 

 weight of chlorine in some minerals. Three minerals 

 were examined, a Canadian sodalite, a Norwegian 

 apatite containing chlorine, and a salt from Central 

 Africa. The hydrochloric acid prepared from these 

 minerals was converted into barium chloride, and 

 comparative experiments were made on the silver 

 chloride obtained from these and from ordinary pure 

 barium chloride. With the sodalite and the apatite 

 the differences observed were of the same order as 

 the experimental error ; in the case of the salt the 

 atomic weight found was 35-60. This difference was 

 proved not to be due to the presence of bromine or 

 iodine, and further experiments with this material 

 will be carried out. — ^M. Laporte : The measurement 

 of the mobility of gaseous ions by the toothed-wheel 

 method. The mobility of gaseous ions has been 

 measured by a method based on that used by Fizeau 

 for the determination of the velocity of light. Some 

 preliminary results are given. — G. Contremoulins : The 

 protection against X-rays of persons other than the 

 operator and patient. The effects of modern X-ray 

 tubes can be felt outside the operating-room, and in 

 thickly populated districts may be a source of danger. 

 Experiments are described bearing on the precautions 

 required to prevent the rays penetrating beyond the 

 operating-room.- — A. Dauvillier : The working of the 

 Lilienfeld tube. — C. Matignon : The principles of 

 some new methods applicable to the determination of 

 molecular weights. The utilisation of chemical 

 equilibria for the measurement of molecular 

 weights. — L. Guillet : The tempering of brasses 

 containing tin. — M. Pierrat : The solubility of 

 various potassium salts in mixtures of water and 

 alcohol. Alcoholic solutions of varying strength in 

 alcohol of the salts examined (potassium bitartrate, 

 perchlorate, chloroplatinate, fluosilicate, and cobalti- 

 nitrite) were prepared by prolonged shaking of the 

 salt with the mixture, the alcohol removed by evapora- 

 tion in a current of dry air, the liquid made up to its 

 original volume with water, and the concentration of 

 the salt determined by the electrolytic conductivity 

 method. Solubilities for each of the above salts are 

 given for six different concentrations of alcohol. — P. 

 Dumesnil : The acid ethyl diethylmalonate. — M. 

 Handoin : Contribution to the study of the globular 

 silica representing the flint clay to the south of the 

 Paris basin. — M. Delepine : The active racemic com- 



