48 THE JOURNAL OF BOTANY 



gressive branch of investigation, one is at first surprised that 

 the present volume, the general arrangement of which remains 

 much the same as in the first edition, has grown only by about 

 200 pages. However, a second glance shows that the author 

 has now prepared what is practically a new book rather than a 

 new edition. The explanation, apart from the author's unrivalled 

 power of discrimination and compression, is simple. When 

 Czapek's book first appeared, it was the most extensive work on 

 biochemistry, but in the meantime there have been published 

 numerous treatises dealing with every branch of the subject, 

 including the great encyclopfedia (BiocJiemisches Handlexicon) 

 edited by Abderhalden, Wehmer's Die Pflanzenstoffe, and a host 

 of smaller works, among which we may mention the fine series of 

 Monogi'aphs on Biochemistry edited by Plimmer and Hopkins. 



It is doubtless owing to the important technical applications 

 of biochemistry that the publication of research papers has been 

 so closely followed and accompanied by that of books summa- 

 rising the results of these researches, with the result that perhaps 

 in no other branch of science can one so readily keep in touch 

 with the latest developments of the subject. Czapek's work, 

 however, stands quite apart from all the others, for it is some- 

 thing more than, and something very different from, a mere ency- 

 clopaedia of the chemistry of plant products. Indispensable though 

 books of the latter class are, there is perhaps even greater need 

 for a philosophical treatise on the chemical physiology of plants, 

 and this is what Czapek has supplied in this new edition of the 

 Biochemie der Pflanzen. Instead of merely expanding the book 

 in order to include the results of work done in biochemistry of 

 plants during the last eight years, Czapek has, by wholesale con- 

 densation and omission of material now available in other compi- 

 lations and in special monographs, been able — without unduly 

 enlarging his work — to give a critical summary of the progress 

 made up to the present time in the direction of ascertaining the 

 nature, relationships, and biological significance of the substances 

 built up and broken down in the course of metabolism. Hence, 

 this still bulky volume, packed with citations and serving as a 

 guide to the extensive literature of the subject, is thoroughly 

 readable, and presents a clear picture of the chemical aspects of 

 plant physiology, which is only rendered the more complete and 

 attractive by the wealth of detail introduced and fitted in place, 

 the author never losing sight of the fundamental principles which 

 the multitudinous details, if less skilfully handled, would tend to 

 obscure rather than to illustrate. 



The volume opens with a concise historical introduction, in 

 which the author reviews the general progress of phytochemistry 

 from the time of Aristotle onwards. The general section (pp. 20- 

 239) contains a critical account of the present state of knowledge 

 and opinion concerning colloids and colloidal phenomena, catalysis 

 and enzyme action, immuno reactions, chemical stimulation, &c. — 

 in short, of the whole of the remarkable body of facts and theories 

 resulting from the application of modern physical chemistry to 



