October 17, 1902.] 



SCIENCE. 



633 



ler ; ' On the circuits of plane curves,' by C. 



A. Scott ; ' Note on the real inflexions of plane 

 curves/ by C. A. Scott ; ' La theorie des 

 plaques elastiques planes,' by J. liadaniard; 

 ' Covariants of systems of linear differential 

 equations and applications to the theory of 

 ruled surfaces,' by E. J. Wilozynski ; ' On the 

 rank, order and class of algebraic minimum 

 curves,' by A. S. Gale ; ' On superosculating 

 quadric surfaces,' by H. Masclike; 'Algebraic 

 transformations of a complex variable realized 

 by linkages,' by A. Emch ; ' On the determina- 

 tion of the distance between two points in 

 space of m dimensions,' by H. F. Blichfeldt; 

 'A definition of abstract groups,' by E. H. 

 Moore ; notes and errata : volumes 1, 2, 3. 



The opening (October) number of volume 

 9 of the Bulletin of the American Mathemat- 

 ical Society contains : ' Some instructive exam- 

 ples ill the calculus of variations,' by Oskar 

 Bolza ; ' On the sufficient conditions in the cal- 

 culus of variations,' by E. R. Hedrick ; ' Some 

 recent books on mechanics,' by E. B. Wilson; 

 ' On a new edition of Stolz's Allgemeine Arith- 

 metik, with an account of Peano's definition 

 of number,' by E. V. Huntington; 'Lazarus 

 Fuchs,' by E. J. Wilczynski ; ' Notes ' ; ' New 

 Publications.' The November Bulletin con- 

 tains : ' The Ninth Summer Meeting of the 

 American Mathematical Society,' by Edward 

 Kasner ; ' The Meeting of Section A of the 

 American Association for the Advancement 

 of Science, Pittsburgh, Pa., June 28 to July 

 3, 1902,' by E. S. Crawley; 'Second report 

 on recent progress in the theory of groups of 

 finite order,' by G. A. Miller; 'Shorter No- 

 tices'; 'Notes'; 'New Publications.' 



The September number of the Botanical 

 Gazette contains the following papers : Dr. E. 



B. Copeland begins an historical and critical 

 discussion of 'The Else of the Transpiration 

 Stream,' based upon an extended series of ex- 

 periments that he carried on at the Hull 

 Botanical Laboratory. The paper will be no- 

 ticed more fully upon its completion. Harley 

 P. Chamder publishes a revision of Nemophila, 

 a genus which has occasioned considerable 

 difference of opinion among Calif ornian botan- 

 ists. The author defines eighteen species and 



varieties, giving full discussion of critical 

 points, synonymy, and citation of collections. 

 Mr. W. C. Worsdell gives an account of his 

 views concerning ' The Evolution of the Vascu- 

 lar Tissue of Plants,' beginning with the solid 

 stele, which he thinks was derived from some 

 bryophytic ancestry, and which is displayed 

 among the most primitive ferns, and also in 

 the juvenile stages of all ferns. The various 

 stages ill the evolution of the vascular tissue 

 from this condition the author describes and 

 illustrates. Professor Conway MacMillan sug- 

 gests a classification of seeds in accordance 

 with modern ideas of their structure and func- 

 tion. He gives general, structural, and genetic 

 classifications. D. G. Fairchild describes 

 Mimosa pudica as a weed in Ceylon, and re- 

 produces a photograph of a large patch of it 

 between Peradeniya and Colombo. 



SHORTER ARTICLES. 



ON THE STRUCTURE OF THE NUCLEUS. 



1. Hitherto the only irrefragable evidence 

 showing that condensation is promoted by 

 ionization, or in other words that negative 

 ions are somewhat more active as condensation 

 nuclei than positive ions, is the brilliant ex- 

 periment devised by C. T. E. "Wilson.* 

 Nuclei are here produced by the X-rays in 

 communicating condensation chambers, on the 

 two sides of a vertical earthed metal plate, 

 which receives electrical current normally on 

 one side, through the ionized air, saturated with 

 water vapor, and transmits the current in the 

 same way and through the same medium on 

 the other side. Necessarily there was an ex- 

 cess of negative ions on one side of the plate 

 and an excess of positive ions on the other 

 side. It was found, on producing condensation 

 by exhaustion simultaneously on both sides 

 under like conditions, that the fogs subsided 

 on the positive side many times as rapidly as 

 they did on the negative side, or that the 

 negative ions are in correspondingly greater 

 number. The effect is increasingly marked 

 for smaller supersaturations. 



2. On extending my work with shaken 

 nuclei to solutions of non-conductors in non- 

 conductors, such as naphthalene and of paraf- 



♦ Phil. Trans. Lond., Vol. 193, pp. 289-308, 1899. 



