September 17, 1915] 



SCIENCE 



383 



The Electron Theory of Matter. By 0. W. 

 EiCHARDSON, Wheatstone Professor of 

 Physics at Kings College, London. Pp. vi 

 ■+612. Cambridge Univ. Press. 1914. 



This is in many ways a very remarkable 

 book. Its scope is broader than tbat of any 

 book on Electron Theory which has yet ap- 

 peared, and it has the unique merit of not fol- 

 lowing even remotely the outline of J. J. 

 Thomson's epoch-making work in this field. 

 The author himself has exhibited within the 

 past fifteen years, an unusual combination of 

 theoretical and experimental fertility, and the 

 present volume represents his digest, from the 

 beginning, of the whole field of electromag- 

 netic theory from both the theoretical and the 

 experimental side. It exhibits profundity of 

 scholarship, breadth of knowledge, enormous 

 industry and a commendable fairness and rea- 

 sonableness of temper. 



The first 216 pages contain mainly the 

 author's own treatment of nearly all of the 

 most important of the classical theorems of 

 electromagnetism such as the various potential 

 theorems and those growing out of the Max- 

 well equations. From this point on is found a 

 very exhaustive and original treatment of 

 practically all of the newer developments of 

 physics the scope of which can best be seen 

 from the chapter headings. There are eighty 

 pages on the electrodynamics of a moving 

 charge, including a full discussion of the 

 Abraham and Lorenz theorems ; sixty pages on 

 relativity; thirty-five on radiation and tem- 

 perature with Wien's and Planck's contribu- 

 tions ; forty on the theory of magnetism with a 

 full review of Weiss' work; seventy-five pages 

 on the electron theory of metallic conduction, 

 thermo electromotive force, and thermoionics ; 

 thirty-five pages on " Types of Eadiation " 

 corpuscular and ethereal, including recent 

 X-ray theory ; thirty-five pages on spectroscopic 

 phenomena ; forty on the structure of the atom 

 with Thomson rather overdone and Nicholson 

 and Bohr somewhat slighted; and sixteen on 

 gravitation. 



Altogether it is a book of large and perma- 

 nent value and another testimony to the 

 breadth and fecundity of British science. 



E. A. MiLLIKAN 



Kyeeson Physical Laboratory, 

 University op Chicago 



SPECIAL ABTICLES 



A SYSTEM OF RECORDING TYPES OF MATING IN EX- 

 PERIMENTAL BREEDING OPERATIONS^ 



All Mendelian experimentation with bisex- 

 ual forms implies a system of mating which in 

 practical work is called line breeding. One 

 starts any Mendelian experiment with two 

 kinds of organisms which are crossed with each 

 other to produce the Fj generation. Then the 

 Fj individuals are either mated inter se or 

 back-crossed to the parent forms. The F^ in- 

 dividuals may be mated in a variety of ways 

 inter se and with the parents or grandparents. 



Many of those engaged in Mendelian work 



P generation 



Diagram I 

 BPRd' X Houdan 9 



Fi generation Ficf X Fi 9 from reciprocal cross 

 Fj generation Fat? XBPR9 



Fs generation Fsd^M 



Diagram II 

 P generation Houdan cf X BPR 9 



Fi generation Fid' 



X Houdan 9 



Fs generation Fjcf X Fi 9 from reciprocal cross 



Fs generation Fs 9 iV 



must have experienced the same difficulty that 

 the writer has in recording experimental re- 

 sults, namely, that of expressing adequately 

 and completely, and at the same time briefly 

 and simply the general nature or type of the 

 1 Papers from the Biological Laboratory of the 

 Maine Agricultural Experiment Station, No. 88. 



