REVIEWS 697 



we find no mention of the characteristic compound starch grains of several cereals, 

 or the distinctive laticiferous vessels of the official Chelidonium. 



Indeed one cannot but feel that the text does not do justice to the quality of 

 the admirable illustrations. E. J. SALISBURY. 



Soil Conditions and Plant Growth. Third Edition. By E. J. Russell, 

 D.Sc. (Lond.), F.R.S. [Pp. viii + 243, with 14 diagrams.] Monographs on 

 Biochemistry. (London : Longmans, Green & Co., 1917. Price 6s. 6d. net.) 



The publication of a third edition of this excellent survey of our present-day 

 knowledge of the soil in its relation to plant life is sufficient guarantee not only of 

 its proved usefulness but also of the growth of interest in the subject. Since the 

 first appearance of this work five years ago, numerous alterations and several 

 important additions have been made to the text, consequent upon the considerable 

 advances that recent years have witnessed in this field. 



A chapter treating of the micro-organisms of the soil in relation to plant growth 

 was added in 191 5, and the present edition includes a much-needed account of the 

 colloidal properties of the soil. This latter affords the author an opportunity of 

 dealing with adsorption, and so to fill what constituted a very obvious gap in the 

 earlier work. The subject of chemical reaction, especially in relation to soil 

 acidity, is here also dealt with, we venture to think too briefly, having regard to its 

 influence on vegetation and economic importance. 



Apart from minor alterations, the remaining seven chapters maintain much of 

 the form and scope of the original work, and deal respectively with : The History 

 of the Subject ; The Requirements of Plants ; The Composition of the Soil ; The 

 Carbon and Nitrogen Cycles in the Soil ; The Soil in Relation to Plant Growth ; 

 Soil Analysis and its Interpretation ; and The Biological Conditions in the Soil. 



It is a matter for regret that, in so comprehensive a volume, the author did not 

 make the last-named chapter the occasion for treating, however briefly, of the 

 biotic relations between plant and plant, since many of the edaphic factors are 

 often probably in the main indirectly operative through this agency. 



The Appendix on methods of Soil Analysis has been brought up to date by the 

 inclusion of Hutchinson and McLennan's method for determining the lime require- 

 ment of soils, and the Bibliography has also been extended by the addition of 

 references to recent papers. 



The subject-matter generally is treated of more from the chemical than the 

 biological standpoint, and here and there the latter aspect tends to become too 

 much subordinated. This it is that constitutes the chief weakness of the chapter 

 on " The Soil in Relation to Plant Growth." 



The book as a whole is, however, one that can be confidently recommended to 

 all students of plant life, and, indeed, is an almost indispensable item in the 

 equipment of the bookshelf, either of the agricultural student, the ecologist, or 

 the general biologist. For either of these Dr. Russell has provided an excellent 

 book of reference, containing a large amount of information in a condensed form, 

 a phase of usefulness that would be greatly enhanced by the provision of an 

 adequate index. E. J. Salisbury. 



British Grasses and their Employment in Agriculture. By S. F. Arm- 

 strong, F.L.S. [Pp. viii + 199, with 175 illustrations.] (Cambridge: at 

 the University Press, 191 7. Price 6s. net.) 



As the author states in his preface, this volume has been written primarily to 

 supply the needs of agricultural students. With the object of meeting the special 



