156 SCIENCE PROGRESS 



This book gives accounts of various physico-chemical phenomena as apphed 

 to organisms, such as will not be found elsewhere. The chapter on " The 

 Colloidal State " will dehght all biologists, and should be read carefully by 

 senior students of both botany and zoology. 



In this edition the original book has been broken up into two parts, the 

 first herein reviewed, treating of the more chemical side of the subject ; 

 Part II, now in preparation, being devoted to more purely physiological 

 problems. 



This " Introduction " to the chemistry of Plant Products may be wel- 

 comed as a reliable statement of the present-day status of our knowledge of 

 vegetable physiological chemistry. T B G 



Soil Alkali : Its Origin, Nature, and Treatment. By F. S. Harris, Ph.D., 

 Director Utah Agricultural Experiment Station. [Pp. xvi + 258, 

 with 33 illustrations.] (New York : John Wiley & Sons ; London : 

 Chapman & Hall, 1920. Price 13s. 6d. net.) 



This book is intended for students, agricultural advisers, and the better 

 trained farmers, concerned with farming alkali lands. It attempts to discuss 

 the widely scattered literature on a subject of ever-increasing importance, and 

 bristling with urgent and unsolved problems. 



Of the total land of the earth, no less than half is under arid conditions 

 and is therefore liable to drought, and alkali, or both. European investigators 

 have paid little or no attention to the subject, since Europe is practically free 

 from soil alkali. But it is the only continent in this happy position. 



The increasing demand for food has necessitated an increase in the land 

 under cultivation, mainly in arid areas, and there the alkali problem, as the 

 author points out, is twofold. Contaminated land must be reclaimed, and 

 land free must be irrigated in such a way that alkali does not develop. A 

 proper understanding of the nature and origin of alkali is necessary before any 

 reliable advice can be given on its treatment. One of the main dangers is that 

 increased evaporation, due to irrigation, brings up soluble salts and concen- 

 trates them at the soil surface. Hence, drainage is as important as irrigation. 

 This is especially the case now that continuous irrigation is replacing the basin 

 method. The latter only permits one crop per year, but at the same time it 

 carries the deleterious salts downwards ; the newer method, although allowing 

 more crops, produces almost continuous evaporation and consequent accumu- 

 lation of salts. This can be prevented, to a certain extent, by proper culti- 

 vation of the land, and by using less irrigation water. The book would be 

 improved if the double value of reduced irrigation — both in the saving of water 

 and the better crop — were discussed more fully. Material for this discussion 

 already exists both in America and in the work of the Howards at Quetta, 

 India. 



The practical man will find the chapters dealing with native vegetation 

 as an indication of alkali, and suitable crops for alkali land, of considerable 

 interest and use. The chemist who has to analyse the soil for its alkali 

 content will also find the appropriate chapters of interest, but for an entirely 

 different reason. The author has described and compared the best known 

 methods, and a perusal of them will show the chaotic condition of this branch 

 of the subject. Under these circumstances the six whole pages of tables 

 dealing with the electric bridge method of determining total salts could well be 

 omitted. Tables are expensive to print, and the description given of the 

 instrument is hardly sufficient to warrant their inclusion. In addition, recent 

 work on conductivity of solutions throws considerable doubt on the accuracy 

 of the results hitherto obtained. It is to be hoped that future editions of the 

 book will contain, in place of the tables, a fuller discussion of Osterhout's 

 views on antagonism. 



