Januarv 30, 1908] 



NATURE 



311 



gas, not the faintest trace of helium was obtained. The 

 view is put forward that the effect is due to a secondary 

 decomposition of the glass under local heating during the 

 bombardment, and that it is not due to the discharge gases 

 being driven into the glass. 



Royal Microscopical Society, December 18, 1907.— 

 Mr. Conrad Beck, vice-president, in the chair. — Specimens 

 of luminous bacteria : J. E. Barnard. On the room being 

 darkened, the light given off by the bacteria was at once 

 apparent, and the contents of the flask when shaken be- 

 came very luminous. The light produced was nearly 

 monochromatic, lying between the lines F and G of the 

 spectrum. The whole energy of these bacteria seemed to 

 be utilised in producing light, no heat whatever being 

 detected. — Specimens of natural twin-crystals of selenite : 

 E. Large. Specimens were also exhibited under special 

 reflecting polariscopes ; under some of these were also 

 shown artistic subjects made from selenite, one representing 

 a vase of flowers, and another flowers and fruits, with 

 animals, such as parrots, chameleons, &c., which changed 

 colour when a film of mica below the design was rotated. 

 Mr. Large also exhibited a small double-image prism made 

 from a fragment of Iceland spar and mounted on the nose 

 of an objective, by means of which two images of a suit- 

 able object placed on the stage with a selenite plate were 

 obtained in complementary colours. — Gregory and \\'right's 

 microscope : E. M. Nelson. This microscope was de- 

 scribed and illustrated in an old and rare book published 

 by Gregory and Wright in 1786, and was called a " nevir 

 universal microscope, which has all the uses of the single, 

 compound, opaque and aquatic microscopes." The illus- 

 tration shows it to be very similar to one presented to the 

 society in 1899 by Dr. Dallinger, which was then thought 

 to have been made by Benj. Martin, but it now seems 

 likely that it was made by Gregory and Wright, who were 

 probably Martin's successors. — A correction for a spectro- 

 scope : E. M. Nelson. The paper described a device bjr 

 which the object-glass of the telescope may be automatic- 

 ally rotated so as always to receive the rays from any 

 part of the spectrum without obliquity. — Some African 

 rotifers : J. Murray. The paper described about twelve 

 species of Bdelloid rotifers from Old Calabar, Uganda, and 

 Madagascar, among which were one new species and two 

 new varieties. 



January 15. — Mr. E. J. Spitta in the chair. — .\ new 

 method of showing living bacteria by dark-ground 

 illumination : C. Beck. The apparatus consisted of a 

 modified parabolic illuminator, a Nernst lamp, and mono- 

 chromatic blue light filter. — Some microscopes of new 

 design made. by Messrs, Leitz : J. W. Ogiivy. The instru- 

 ments were fitted with Leitz 's fine adjustment, the 

 arrangement consisting of a worm wheel and heart-shaped 

 cam, which gives an alternate rise and fall of 3 mm. to 

 the body, of the microscope. Mr. Ogilvy said an important 

 feature in the arrangement was that, in the event of the 

 objective being brought into contact with the cover glass 

 when focussing, it simply rested upon the slide, no further 

 downward motion being imparted to the body even if the 

 observer continued to turn the milled head. The coarse 

 adjustment was also provided with a safety arrangement. 

 — The microscope as an aid to the study of biology in 

 entomology, with particular reference to the food of 

 insects : W. Wesche. 



Edinburgh. 



Royal Society, January 6. — Prof. Crum Brown, F.R.S. , 

 vice-president, in the chair. — The chairman read a pre- 

 liminary obituary notice of the late president, Lord Kelvin 

 (see p. 253). — The fossil Osmundaceae, part ii. : D. T. 

 Gwynne-Vaughan and R. Kidston, F.R.S. The present 

 part begins with a full account of the synonymy of scorral 

 fern stems of osmundaceous affinity from the Permian of 

 Russia. The internal structure of two of these, Zalesskya 

 gracilis and Z. diploxylon (the latter a new species), is 

 described in detail. They form a primitive genus of the 

 Osmundacea?, and are especially characterised by the 

 possession of a broad and perfectly continuous ring of 

 xylem, from which the leaf-traces depart in protostelic 

 manner. The xylem is nori-parenchymatous, and most of 

 the trachea; bear multiseriate pits. The proloxylems of the 

 leaf-traces are shortly decurrent into the stele of the stem 



NO. 1996, VOL. y'j'\ 



as mesarch strands dving out rapidly below. Two dis- 

 tinctly different regions are to be observed in the xylem, 

 a peripheral zone of normal tracheae and a central mass 

 of short and wide elements with reticulate markings. In 

 the living plant of Z. diploxylon the latter tissue occupied 

 the whole of the centre of the stele, which therefore 

 possessed a solid central mass of xylem. It follows that 

 the central ground-tissue of the recent Osmundaceje triust 

 be regarded as a true pith derived from the modified 

 central xvlem of such a stele. The phloem consists of 

 metaphlcem only, there being no protophloem or porous 

 lavers. 



P.ARIS. 



Acfdemy of Sciences, lanuaty 20. — M. Henri Becquerel. 

 in the chair. — The principal earthquake centres in France, 

 and on the svslem of seismic stations that should be 

 established : G. Bigourdan. Taking into account the 

 stations already existing or now being established, further 

 stations are suggested at Nice, Marseilles, Rennes, and 

 Lille. — Concerning a tooth discovered by MM. Maurice 

 de Rothschild and H. Neuville : Albert Gaudry. It is 

 concluded that this tusk, found near Addis-Abeba, belongs 

 to a large unknown .African mammal, now existing or 

 recently extinct. — Morphological variations, obtained artifi- 

 cially, "of the tubercle bacillus of man and mammals ; S. 

 Arloing. An account, accompanied by reproductions of 

 photographs, of the modifications produced in human and 

 bovine tubercle bacilli by prolonged cultivation at either 

 a high temperature (45°) or high pressure (2-5 atmo- 

 spheres). — A differential system of the second degree: L. 

 Schlesingrer. — The periodic solutions of certain functional 

 equations : Ernest Esclangon. — Methodical attempts at a 

 cellular aeroplane : H. Farman. A detailed account of 

 the steps bv which the author constructed his aijroplane 

 and learnt its use. — The efficiency of screws for propulsion 

 in the air : Louis Bregruet. — the study of radio-active 

 lead : B. Szilard. Radium D, E, and F have been 

 separated from radio-lead. The present paper is concerned 

 with the best methods of effecting this separation. — .\n 

 exceptional case of Zeeman's phenomenon : A. Dufour. 

 It is shown that there exists at least one source of light, 

 a flame in which calcium fluoride is volatilised, giving a 

 spectrum attributed to a compound and not to an element, 

 which, placed in a magnetic field, gives out circular vibra- 

 tions the sense of which agrees with the hypothesis of 

 the existence of positive electrons. — The calorimetric 

 method applied to the study of slow reactions : Jacques 

 Duclaux. A closed Dewar" tube is used as the calori- 

 metric vessel, the whole being placed in the water of a 

 thermostat. As showing the accuracy obtainable, an 

 example of the application of the method to tjie hydrolysis 

 of ethvl acetate by potash is given. — The synthesis of 

 ammonia : M. Woltereck. — The catalytic power of silica 

 and alumina : J. B. Senderens. The catalytic effect pro- 

 duced bv silica or alumina depends upon the state of 

 division and also upon the temperature to which these 

 substances have been raised. Thus precipitated silica, 

 dried by a gentle ignition, at 280° acts upon alcohol giving 

 99-5 per cent, of ethylene. The same silica, calcined for 

 one hour at a red heat, gives ethylene and 5-3 per cent, 

 of hvdrogen. .\fter six hours' ignition, the decomposition 

 takes place only at 390°, and the amount of hydrogen 

 increases to 17 per cent. Alumina behaves in a similar 

 manner. — Some compounds of terbium and dysprosium : 

 G. Urbain and G. Jantsch. Salts of these elements 

 having been recently isolated in a pure state by the 

 authors, they have studied the properties of some of their 

 compounds with the view of devising less tedious methods 

 of separation. The present note contains an account of 

 terbium peroxide, Tb,0- ; nitrate, Tb(NO,)„6H.O ; 

 sulphate, Tb,(S0J,,8H,0 ; and chloride, TbCl,,6H,0. 

 Dvsprosium does not form a peroxide, but the properties 

 of' the nitrate, Dv(NO,),,';H.,0 ; sulphate, Dy,(S0,,)„8H,0 : 

 and chloride, DyCl.,,6H,0, are described.— The heats of 

 solution of the alkali metals and the heats of formation 

 of their protoxides : E. Rengrade. On account of _ the 

 violence of the action of water upon these metals, especially 

 caesium and rubidium, the reaction was allowed to take 

 place in a modified Berthelot bomb. The results are very 

 concordant, and lower than those previously obtained by 

 other methods. — The estimation of sulphide of carbon in 



