March 13, 1919] 



NATURE 



39 



propagated by cuttings, is much planted in the streets 

 of towns in Europe and the United States, where it 

 surpasses all other trees in resistance to evil condi- 

 tions of soil and atmosphere. It has all the characters 

 of a first cross, its leaves and fruits being intermediate 

 between the two wild species, P. orientalis and P. 

 occidentalis, while its vigour is remarkable. It more- 

 over produces, when its seeds are sown, a mixed and 

 diverse crop of seedlings, in which arc variously com- 

 bined the characters distinctive of the two parent 

 species. The London plane probably originated as a 

 chance seedling in the Oxford Botanic Garden some 

 time before 1670. Specimens of its foliage, preserved 

 in the Sloane Herbarium at Oxford, were collected by 

 Bobart about that date, and bear the label Platamis 

 media, showing that it was then recognised as a hybrid 

 between the Oriental and Occidental planes. This date 

 agrees with the recorded age of the largest London 

 plane known, a magnificent tree at Ely, no ft. in 

 height and 23 ft. in girth. Certain cultivated varieties, 

 as P. pyramidalis, P. hispanica, etc., appear to have 

 originated at a later date as chance seedlings of 

 P. acerifolia. as is shown by their histoi-y and a careful 

 study of their botanical characters.' A complete 

 description of the fruit and leaves of all the species 

 of the genus and of the hybrids is given. The lobing 

 of the leaves, an important character, is measured bv 

 a new method. — J. A. McClelland and P. J. Nolan": 

 The nature of the ions produced by phosphorus. 

 Previous work by the authors and J. J. Nolan has 

 shown the existence of groups of ions of different 

 mobilities produced by spraying water or by bubbling 

 air through mercury or alcohol. The present work 

 shows that similar groups of ions are present in air 

 which has passed over phosphorus. The mobilities 

 range from 022 cm. per sec. to 0000053 cm. per sec. 

 in a field of i volt per cm. Drying the air before 

 passing it over the phosphorus brings the more mobile 

 groups into prominence. Three groups of ions of 

 lower mobilities than the atmospheric large ion were 

 observed. The conclusion as to the nature of the 

 phosphorus ions is that they are composed mainly of 

 water. 



Paris. 

 .Academy of Sciences, February 24.— M. L^on Guignard 

 in the chair.— C. Richet, p' Brodin, and Fr. Saint- 

 Girons : Some haematic phenomena in anaphylaxy 

 and anlianaphylaxy. Three new facts are brought 

 out by experiments on dogs. In anaphylaxy the blood 

 is profoundly modified by the appearance of nucleated 

 red corpuscles, by an increase in concentration, and 

 by the disappearance of the polynuclear cells. — A. 

 Blondel : Application of the theory of the two re- 

 actions to the calculation of the forced oscillations 

 of synchronised alternators. — M. Balland : Military 

 soups. — M. Daniel Berthelot was elected a member of 

 the section of physics in succession to the late E. H. 

 Amagat.— A. Denjoy : A property of functions with 

 complex variables. — M. Risser : Formulae representa- 

 tive of trajectories.— M. Mesnager : Maximum values 

 of the tension near the lower face of a square plate 

 supporting a single load concentrated at its centre.— 

 E. Faure : The gyroscopic force of liquids. — A. 

 V^ronnet : The central temperature of the sun. — A. 

 Sanfourche : The oxidation cycle of nitric oxide in 

 presence of water. The oxidation of nitric oxide in 

 presence of water gives nitrous anhydride, and not 

 nitrogen peroxide, as the intermediate product. — E. 

 Liger : The o- and fl-ox)dihydrocinchonines and their 

 rdle in the production of certain isomers of cinchonine. 

 — F. Grandjean : Some new examples of the calcula- 

 tion of the extraordinary rays for certain structures 

 of anisotropic liquids. — J. Renaud : Difficulties met 

 with in the study of storms as a result of the uncer- 

 NO. 2576, VOL. 103] 



tainty of the time of the observations. The change 

 over from Greenwich time to summer time causes 

 difficulty with self-recording instruments, and in 

 several cases it is not clear from the records whether 

 the chart was changed on the date of the change of 

 time.— L. Joleaud : The migrations of the genera 

 Hystrix, Lepus, Anchitherium, and Mastodon at the 

 Neogene epoch. — Em. Bourquelot and H. Hdriisey : 

 Application of the biological method to the study of 

 the leaves of Hakea laurina. The extraction of a 

 glucoside (arbutin) and quebrachite. By the succes- 

 sive action of invertin and emulsin, these leaves were 

 proved to contain cane-sugar, quebrachite, and two 

 hydrolysable glucosides, one of which, arbutin, was 

 identified. — G. Petit : Remarks on the morphology of 

 the phrenic centre of mammals.— P. Armand-Del'ille : 

 Considerations relating to the unicist conception of 

 the haematozoa of benign and malignant tertiary fever. 

 —MM. Boqnet and L. Nigre : Infection, sensibilisa- 

 tion, and immunity in epizootic lymphangitis of the 

 Solipeds. — E. Belot : The economical organisation of 

 commercial motor transports in a large town. 



BOOKS RECEIVED. 



Essentials of Volumetric Analysis. An Introduction 

 to the Subject. Adapted to the Needs of Students of 

 Pharmaceutical Chemistry. By Prof. Henry W. 

 Schimpf. Third edition, rewritten and enlarged. 

 Pp. xiv + 366. (New York: John Wiley and Sons, 

 Inc. ; London : Chapman and Hall, Ltd., 1917.) 75. 

 net. 



Integral Calculus. By Prof. H. B. Phillips. Pp. 

 V+194. (New York: John Wiley and Sons, Inc.; 

 London : Chapman and Hall, Ltd., 1917.) 6a-. net. 



Elements of General Science. By Prof. Otis Wil- 

 liam Caldwell and W. L. Eikenberry. Revised edi- 

 tion. Pp. xii + 404. (London: Ginn and Co., 1918.) 

 5s. 6d. net. 



.Agricultural Laboratory Exercises and Home Pro- 

 jects Adapted to Secondary Schools. By Henry J. 

 Waters and Prof. Joseph D. EUiff. Pp. vi + 218. 

 (London : Ginn and Co., 1919.) 45. 6d. net. 



A Century of Science in America. VVith Special 

 Reference to the American Journal of Science, 1818- 

 19 18. By Edward Salisbury, Dana, and others. Pp. 

 458. (New Haven : Yale University Press ; London : 

 Oxford Universitv Press, 1918.) 17s. net. 



Militarv Geologv and Topography. A Presentation 

 of Certain Phases' of Geology, Geography, and Topo- 

 graphv for Military Purposes. Edited by Herbert E. 

 Gregory. Prepared and issued under the auspices of 

 the Division of Geology and Geography, National 

 Research Council. Pp. xv+281. (New Haven: Yale 

 University Press ; London : Oxford University Press, 

 1Q18.) 55. 6d. net. 



.\ Practical Handbook of British Birds. Edited by 

 H. F. Witherby. In eighteen parts. Part i. Pp. 

 xvi+644-2 plates. (London: Witherby and Co., 

 19 19.) 4s. net oer part. 



Introductory "Meteorology. Prepared and issued 

 under the auspices of the Division of Geology and 

 Geography, National Research Council. Pp. xii + 

 150. (New Haven : Yale University Press, 1918.) 

 4s. 6d. net. 



The Year-Book of the Scientific and Learned 

 Societies of Great Britain and Ireland. Thirtv-fifth 

 annual issue. Pp. vii + 333. (London : Charles Griffin 

 and Co., Ltd., 1918.) gs. net. 



The Science of Labour and Its Organisation. By 

 Dr. Josefa lotevko. Pp. viii+Kjq. (London: George 

 Routledge and Sons. Ltd., 1919-) 3*- ^- "«*• 



La Gen^se de la Science des Cristaux. Par H^lfene 



