30 



SCIENCE 



[N. S. Vol. XXXVIII. No. i 



6. The connection between the Beta and the 

 Gamma rays, the recent investigation of 

 which has raised new and interesting ques- 

 tions regarding the nature of electro-mag- 

 netic radiation itself. 



6. The elaborate study of the thorium and 

 actinium series of products, a study which has 

 been chiefly responsible for the extension of 

 the twenty radioactive products knovm in 

 1905, to the thirty-two known in 1913. 



7. The new evidence for and against the ac- 

 tivity of ordinar.y matter. 



8. The bearing of radioactivity upon the age 

 of the earth. 



The author's style is always direct and 

 simple and the present book, like its predeces- 

 sor, can be read by those not trained in severe 

 mathematical analysis. At the same time, the 

 work of compiling has been carefully and 

 thoroughly done, the references to the original 

 articles are complete, and the author has been 

 remarkably successful in dealing fully and 

 fairly with the work of other investigators and 

 in making a thorough and complete presenta- 

 tion of the facts and theories of radioactivity 

 as they stand in the year 1913. This book will 

 undoubtedly be the standard work on radioac- 

 tivity for the next five or six years at least. 



E. A. MiLLIKAN 



tjniveesity of chicago, 

 Kyerson Physical Laboratory, 

 June 2, 1913 



SCIENTIFIC JOURNALS AND ABTICLES 



The April number (volume 14, No. 2) of 

 the Transactions of the American Mathemat- 

 ical Society contains the following papers : 



J. L. Coolidge: "A study of the circle cross." 



W. W. Denton: "Projective dififerential geom- 

 etry of developable surfaces." 



K. P. Williams : ' ' The solutions of non-homo- 

 geneous linear difference equations and their 

 asymptotic form. ' ' 



A. B. Coble: "An application of finite geom- 

 etry to the characteristic theory of the odd and 

 even theta functions. ' ' 



W. F. Osgood and E. H. Taylor: "Gonformal 

 transformations on the boundaries of their regions 

 of definition." 



The May number (volume 19, number 8) 



of the Bulletin of the American Mathematical 

 Society contains: Report of the February 

 meeting of the Society, by F. N. Cole ; " Three 

 or more rational curves collinearly related," 

 by J. E. Howe ; " Second note on Fermat's 

 last theorem," by E. D. Carmichael ; " An ex- 

 tension of a theorem of Painleve," by E. H. 

 Taylor ; " Mathematical physics and integral 

 equations," by W. A. Hurwitz ; " Shorter 

 Notices " : Schulze's Teaching of Mathematics 

 in Secondary Schools, by J. L. Coolidge; 

 Hime's Anharmonic Coordinates, by J. V. 

 McKelvey; Beutel's Algebraische Kurven, 

 Zweiter Teil, by H. S. White; Scheffer's Lehr- 

 bueh der Mathematik fiir Studierende der 

 Naturwissenschaften und der Technik, by A. 

 E. Crathorne; Sainte-Lague's Notions de 

 Mathematiques, by E. C. Archibald; Weber 

 and Wellstein's Encyklopiidie der Elementar- 

 Mathematik, Band III., by J. B. Shaw; Whit- 

 taker's History of the Theories of the ^ther 

 and Electricity, Krause's Theorie der ellip- 

 tischen Funktionen and Mill's Introduction to 

 Thermodynamics, by E. B. Wilson; Annuaire 

 du Bureau des Longitudes pour I'An 1913, by 

 E. W. Brown; "Notes"; "New Publications." 

 The June number of the Bulletin contains: 

 Eeport of the spring meeting of the Chicago 

 Section, by H. E. Slaught ; " Concerning two 

 recent theorems on implicit functions," by L. 

 L. Dines ; " Concerning the property A of a 

 class of functions," by A. D. Pitcher; "The 

 asymptotic form of the function *(a;)," by K. 

 P. Williams ; " An erroneous application of 

 Bayes' theorem to the set of real numbers," 

 by E. L. Dodid; "Shorter Notices": Weber's 

 Partielle Differential-Gleichungen der mathe- 

 matischen Physik, Band II., and Foppl's The- 

 orie der Elektrizitat, Band I., by J. B. Shaw; 

 " Notes " ; " New Publications." 



SPECIAL ARTICLES 

 accessory chromosomes in the pig 

 Several points of interest were brought to 

 light in this study of the spermatogenesis of the 

 pig and the relation of the accessory chromo- 

 somes to sex. Unusually good material was 

 available for this investigation and it was 

 found that eighteen chromosomes occur in the 



