552 



NATURE 



[October 6, 1904 



to one who has long tried to discover what preys on 

 these small succulent creatures. Those that are bigjj^er 

 of build prey upon the smaller, and a large infusorian 

 will swallow a small rotifer, but the fresh-water mussel 

 is a giant who devours great and small impartially. 



The paper on snails and slugs is good throughout, 

 and might with advantage have been extended beyond 

 the thirty pages allotted to it. The want of space is 

 due to the attempt to make the book useful to the 

 systematist and the collector, as well as to the observer 

 and student of the lives of animals. No less than 

 eleven pages are devoted to the definitions of the 

 different species of British land and fresh-water 

 gastropods, and, after all, they are too brief to be of 

 much use to the collector. Why, then, insert them at 

 all? In the same way no less than eight pages are 

 expended on the specific characters of dragonflies. 

 Where, as in the case of the British Amphibia, there 

 are but few species, the descriptions are fuller and 

 well suited to what I take to be the aim and purpose 

 of the book, viz. to help and encourage the genuine 

 student and observer as distinguished from the mere 

 collector. Altogether the book is an admirable one. 

 Though the waste of space which has been pointed out 

 is to be regretted, it does not interfere with the excel- 

 lence of the rest. The illustrations, fifty-four in 

 number, are good. F. W. H. 



Ol]R BOOK SHELF. 

 The Purification of Sewage. By S. Barwise, M.D., 

 B.Sc. Pp. xiv + 220. (London: Crosby' Lock- 

 wood and Son, 1904.) Price lox. 6d. net. 

 The author has in the present edition attempted to 

 brmg the information available upon this important 

 subject up to the present state of knowledge and 

 practice, and he has added to the former edition an 

 appendix in which the processes in common use for 

 the chemical examination of sewage and sewage 

 effluents are briefly described. The work bears 

 evidence that it has been written by one who is in 

 touch with the practical side of the recent methods 

 of sewage purification; the text also indicates con- 

 siderable acquaintance with the advances which have 

 been made in the treatment of sewage in various 

 centres of population in this country. 



The matters dealt with briefly 'but usefully in- 

 clude :— the nature, varieties, and chemical nature of 

 sewage ; pollution of rivers by sewage ; and the treat- 

 ment of sewage by land, by 'precipitation, and by the 

 "septic tank," followed by either the intermittent or 

 the percolating bacteria bed. These processes are 

 illustrated by good reproductions of photographs, and 

 by sectional and diagrammatic drawings. The 

 appendix on chemical processes of analysis is also 

 illustrated, but the directions are such as can only 

 be usefully followed by one who has received a train- 

 ing in chemical analysis. 



The book will undoubtedly be of use to those who 

 are responsible for directing and advising on the 

 treatment of sewage. The information furnished, 

 as a whole, is reasonably accurate and up-to-date, but 

 there are portions of the book in which the author 

 appears to show lack of information of published 

 results. Thus his statement on p. 125 of the relative 

 advantages of intermittent and percolating beds 

 leaves out of consideration the very potent aeration 

 of the intermittent bed by the process of gaseous 

 diffusion, since results published by the London 

 NO. 1823, VOL. 70] 



County Council show that even at the bottom of a 

 twelve-foot bed a fair proportion of oxygen was 

 present in the interstitial air; he also appears to 

 hold the opinion that such a bed has a serious 

 tendency to become choked, which is not noticed in 

 properly worked beds ; and he speaks of four feet 

 being " the maximum efficient depth " for such a 

 bed, when he should know that a 12-foot bed has 

 been worked with entirely satisfactory results. In 

 these and in other respects the intermittent bed 

 appears at an unfair disadvantage with the percolat- 

 ing bed. It should be understood that these two 

 methods of subjecting sewage to aerobic purification 

 are at present under trial, and as a verdict is still 

 scarcely obtainable, a cautious statement of their 

 relative merits is desirable. 

 Physiologic des Menschen. By Dr. Luigi Luciani. 



Ins Deutsche iibertragen und bearbeitet. By Dr. 



Baglioni and Dr. Winterstein. Erste und zweite 



Lieferungen. Pp. vii + 322. (Jena: Fischer, 1904.) 



Price 4 marks each. 

 This translation into German of Luciani 's te.\t-book 

 of physiology aims at occupying an intermediate posi- 

 tion between the student's text-book and the larger 

 handbooks, being more complete than the former and 

 less encyclopaedic than the latter. The translators 

 have brought the book up to date by additions 

 summarising more recent work. 



The present first two parts of the work, which is 

 expected to extend to twelve parts, deal with general 

 or cellular physioloev, the ohysiology of the blood and 

 circulation, and the physicochemical phenomena of 

 respiration. 



Very interesting and complete accounts are given 

 of the mechanism of the heart beat, and of the physi- 

 ology of the cardiac muscle and nerves, to our know- 

 ledge of which the author himself has added much. 

 The detailed description of practical methods has been 

 wisely printed in smaller type. 



Useful summaries of the chief sources of the liter- 

 ature of physiology are given at the close of each 

 section. 



A special feature of the work lies in the excellence 

 of the historical introductions to the sections dealt with. 

 The account of the discovery of the circulation is 

 e.xceptionally complete and interesting. 



So far as one can judge from the two parts already 

 published, the difficult task of the collection of facts 

 and their fusion into an interesting whole has been 

 carried out with admirable skill, and the text-book 

 promises to form a most useful and philosophic pre- 

 sentation of the chief facts of physiology. The author 

 and translators are to be congratulated on the produc- 

 tion of a work which is distinguished not only by its 

 mastery of detail, but by its eminently readable 

 character and attractive literary form. The appear- 

 ance of the later parts will be looked forward to with 

 much interest. 

 Kritische Nachtrdge zur Flora der Nordwestdeutschen 



Tiefebene. By Dr. F. Buchenau. Pp. vi + 74. 



(Leipzig : \V. Engelmann, 1904.) Price is. 6d. 

 The " Flora der Nordwestdeutschen Tiefebene " was 

 published in 1894, and was well received. Since that 

 time the author has personally, and with the help of 

 other botanists, collected a number of new localities 

 for plants enumerated in the flora, and new plants 

 have been discovered. As the publishers could not 

 at present undertake a second edition. Dr. Buchenau 

 has prepared this small pamphlet, which forms an 

 appendix. It contains a full numbered list of all the 

 species of the area, but diagnostic characters are given 

 only for new species or varieties, and the additions 

 and eliminations are tabulated at the end of the book. 



