498 SCIENCE PROGRESS 



By far the larger portion of the book describes the details of analysis, and 

 all the methods given appear to be sound and free from unnecessary complica- 

 tions. The exact details of manipulation used in different laboratories vary 

 so widely, however, that it would be impossible to find any experienced 

 chemist who would not prefer to replace some of the methods given by 

 others ; for example, in the colorimetric determination of manganese, the 

 description of separate weighing, solution, treatment with persulphate in the 

 presence of silver nitrate and subsequent comparison of the colour with a 

 known standard would undoubtedly have been an improvement on the 

 method given. The methods for the determination of aluminium, uranium, 

 and zirconium are dealt with in a complete manner, and the portion dealing 

 with the analysis of steel-making alloys should prove of value to all interested 

 in these important materials. 



The matter is well arranged, and the index enables definite determinations 

 to be referred to readily. The book may be strongly recommended to steel 

 works' chemists and to others who have to carry out, from time to time, 

 determinations contained within the scope of the work. 



C. O. Bannister. 



BOTAITY AND AGHICULTURE 



Heredity and Evolution in Plants. By C. Stuart Gager. [Pp. xv + 265, 

 with 113 Illustrations. (Philadelphia : P. Blakiston's Son & Co., 1920.) 



This interesting little book is one of the best elementary accounts of Heredity 

 and Evolution that we have read. Written in simple language, it succeeds 

 not only in conveying a great deal of information, but, what is the more 

 important, the probable significance of our knowledge with a due appreciation 

 of its limitations. 



The first two chapters, which describe the Life History of the Fern, are 

 adapted from the same author's Fundamentals of Botany, and serve as a 

 basis for the general principles dealt with in Chapter III. Alternation of 

 generations is used effectively to illustrate the importance of distinguishing 

 between the inherited characteristics and their visible expression. 



After considering the various theories put forward to explain evolution 

 by Lamarck, Darwin, De Vries and others, and the recent work on Mutations 

 and Mendelian inheritance, the author reviews the evidence from various 

 sources, and devotes two chapters to Palaeobotany and Geographical Distribu- 

 tion. The latter contains a very brief but adequate summary of modern views 

 regarding distribution, means of dispersal, and the age and area hypothesis. 

 The section on fossil plants treats of their distribution in space and time. 



In the final chapters the possible origin of some of the more important 

 groups is considered, and in summarising the divergent opinions any dog- 

 matic attitude is avoided by an immediate exposition of the " other views " 

 which are held. 



The subdivision of the subject matter into paragraphs averaging about 

 one and a half pages each, rather unduly breaks the continuity of the text, 

 but that the author has attained his professed object of providing reliable 

 and readable information of an elementary character most will, we think, 

 agree. 



E. J. S. 



Practical Plant Biochemistry. By M. W. Onslow. [Pp. iii + 178.] (Cam- 

 bridge : at the University Press, 1920. Price 15s. net.) 



Written with the object of filling the gap between Organic Chemistry and 

 Plant Physiology, the subject-matter of this M^ork is divided into ten chap- 

 ters, of which the first provides a short introductioa, ifi vfhich the chief 



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