460 



NATURE 



[August 2, 19 17 



heart into its various chambers and the formation of 

 the valves of the iieart.— Prof, E. T. Whittaker : Com- 

 pound determinants. A general method of reducing 

 compound determinants to simple determinants.— Prof. 

 W. H. Metzler : Vanishing aggregates. This paper gave 

 a generalisation of a theorem due to Sir Thomas Muir. — 

 Dr. J. M. Thompson : A further contribution to our 

 knowledge of Platyzoma inicrophyllum, R. Br, An 

 analysis was given of the spore numbers in the various 

 sporangial types^ and it was shown that the small and 

 large sporangia and spores already described for Platy- 

 zoma are well-defined generic features. The typical 

 spore number for a small sporangium is 32, while that 

 for a large sporangium is 16. The facts available, 

 though insuflficient to show the true nature of the 

 various spore types, strengthen rather than weaken a 

 belief in the heterosporous nature of Platyzoma. The 

 plant is then probably an up-grade fern in which 

 segregation of the microsporangia and megasporangia 

 is not yet complete, and in which the megaspores do 

 not declare their female character until they are shed. 

 Should, however, the sporangial development and spore 

 germination prove the plant to be homosporous, its 

 anomalous structure and unique position among living 

 Pteridophytes will be accentuated. 



Paris. 



Academy of Sciences, July 2. — M. A. d'Arsonval in the 

 chair. — J. Boussinesq : The limiting equilibrium of a 

 sandy mass. — A. Gautier and P. Clausmann : A new 

 method of destruction of tissues for the estimation of 

 arsenic and other mineral matter. The method in 

 current use requires large quantities of nitric and 

 sulphuric acids of a high degree of purity ; the new 

 method now proposed is free from this disadvantage. 

 By drying and heating to 300° C. the material to be 

 examined is brought into a condition in which it can 

 be powdered, and this is mixed with 2 to 3 per cent, 

 of its weight of quicklime and a little water added. 

 The mixture is burnt off in the muffle at a low red- 

 heat. The ash is powdered, taken up with water, and 

 a few drops of sulphuric acid added, filtered and evapo- 

 rated until fumes of acid are given off. After dilution 

 this can be transferred to the Marsh apparatus and 

 the arsenic estimated in the usual manner. The whole 

 examination can be carried through in a day, as 

 against three days' work by the older method. The 

 results of tests proving the accuracy of the process 

 are given. — G. Gouy : The effects of molecular shock 

 on the spectra of gases. — M. Akimoff : Fourier-Bessel 

 transcendentals with several variables. — Ed. Chauvenet : 

 The acid sulphate of zirconyl. — F. Dienert and F. 

 Wandenbuike : The estimation of free chlorine in solu- 

 tions of hypochlorites. The addition of a large excess 

 of ammonium salt to the hypochlorite solution, fol- 

 lowed by potassium iodide, prevents the formation of 

 iodate and allows the direct estimation of chlorine in 

 alkaline solution by arsenious acid.^(The late) A. 

 Cochain : A new manner of understanding the de- 

 formation of the earth's crust.— R. Dubois : Remarks 

 on the recent researches of M. Newton Harvey on 

 biophotogenesis. — Mme. Marie Phisalix and F. Caius : 

 The poisonous properties of the parotidian secretion 

 in species of snakes belonging to the Boideae and the 

 Uropeltideae. — W. Kopaczewski : Researches on the 

 serum of Muraena Helena. The physiological action 

 of the serum. The normal serum possesses very 

 marked haemolytic properties ; these are lost after heat- 

 ing to 56° C. for fifteen minutes. The bacteriolytic 

 properties are not so marked. The serum was devoid 

 of agglutinating or precipitating properties. — F. 

 Mesnil and E. Roubaud : The sensibilitv of the chim- 

 panzee to human naludism.^ — H. Stassano : The 

 sterilisation of liquids in thin lavers bv heat. 



BOOKS RECEIVED. 



The Public School System in Relation to the 

 Coming Conflict for National Supremacy. By V. S. 

 Bryant. Pp. xviii + 78. (London : Longmans and 

 Co.) IS. 6d. net. 



Report of the Commissioner of Education for the 

 Year ended June 30, 19 16, 2 vols. (Washington : 

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Industry, Science, and Education. By Principal 

 E. H. Griffiths. Pp. 70. (Cardiff.: Roberts and Co.) 



IS. 



Index of Spectra. By Dr. W. M. Watts. Appen- 

 dix X. (London: W. Wesley and Son.) 



Memoirs of the Geological Survey. Scotland. The 

 Economic Geology of the Central- Coalfield of Scot- 

 land. Area viii.. East Kilbride and Quarter. By 

 R. G. Carruthers and C, H. Durham. Pp. 

 iv + 55 + map and table of vertical sections. (Edin- 

 burgh: H.M.S.O.) 2s. net. 



The Annual of the British School at Athens. 

 No. xxi. Sessions 1914-1915 ; 1915-1916. Pp. 

 viii + 238 + plates xv. (London: Macmillan and Co., 

 Ltd.) 215. net. 



Correction Tables for Thermodynamic Efficiency. 

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Heat Drop Tables : Absolute Pressure. Calculated 

 bv H. Moss, from the Formulae and Steam Tables of 

 PVof. H. L. Callendar. Pp. 63. (London : E. Arnold.) 

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Continuitv, or From Electrons to Infinitv. Bv Dr. 

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Chemistry in the Service of Man. By Prof. A. 

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CONTENTS. PAGE 



American and Antarctic Geology 441 



Radio-mechanics. ByJ. A. F 442 



The Action of Enzymes. By W. M. B 443 



Our Bookshelf . 443. 



Letters to the Editor: — 



The Radiation of the Stars.— J. H. Jeans, F.R.S. ; 



Prof. A. S. Eddington, F.R.S. . 444 



Forests and Rainfall. By Dr. Hugh Rot>ert Mill . 445 

 Indian Saltpetre. {Illustrated.) By Sir T. E. Thorpe, 



C.B., F.R.S. . 447 



The Promotion of Technical Optics 448 



The Aeroplane Bomber's Problem. By Prof, C. H. 



Lees, F.R.S 449^ 



Notes 45<> 



Our Astronomical Column :— 



Comet 1916^ (WoU) ... 454, 



Variable Proper Motion of S Cassiopeise ...... 4.>4 



The Needs of Astronomy . . 454 



The Transliteration of Russian. By Edward Foord 454 



Science in Education and Administration . . . 455 

 Radio-active Halos. {With Diagrams.') By Prof. J. 



Joly, F.R.S 45^ 



University and Educational Intelligence 45^' 



Societies and Academies 459 



Books Received 460 



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NO. 2492, VOL. 99] 



