October 6, 1923] 



NATURE 



499 



(4) Dr. Falk's book on " Catalytic Action " has not 

 lieen written under the authority of the American 

 Chemical Society, although it is issued by the same 

 publishers, and it differs in style from the monographs 

 fcviewed above only in the absence of the Society's 

 iprint and general introduction. Dr. Falk has 

 ;ently published a book on " Chemical Reactions " 

 which he lays stress on the formation of intermediate 

 Idition-compounds ; he represents these by enclosing 

 le formulae of the reacting substances in large square 

 Ibrackets, similar to those used by Werner to represent 

 co-ordinated complexes. The present volume is in the 

 ^main an interpretation of the phenomena of catalysis 

 [on the basis of this theory. 



The theory itself lacks the preciseness of Werner's 

 |theor>' of co-ordination, and does not lead to any 

 marked simplification of the task of explaining the 

 phenomena of catalysis. In this respect it is indeed 

 less helpful than the crudely mechanical theories of 

 adsorption which have so clearly proved their utility 

 in recent years, and are described in the tenth chapter 

 of this monograph. The author states in his preface 

 that he has not attempted to cover the whole field of 

 catalytic reactions, but has discussed only sufficient 

 cases to illustrate his own particular point of view. 

 Since this point of view is not especially helpful, the 

 ordinary' student would probably be well advised to 

 use a text-book written from a less specialised aspect ; 

 but research-workers on catalysis may well find fresh 

 inspiration in a novel way of looking at familiar facts. 



Characters and History of the Ferns. 



The Ferns {Filicales) Treated Comparatively with a View 

 to their Natural Classification. By Prof. F. O. Bower. 

 Vol. I : Analytical Examination of the Criteria of 

 Comparison. Pp. x + 359. (Cambridge : At the 

 University Press, 1923.) 305. net. 



TirE puI)lication of the present volume is of peculiar 

 interest to all who seek to understand the inter- 

 relationships of li\in,u organisms. Consisting, as it 

 does, of some 360 pages of beautifully produced and 

 liberally illustrated matter, this book is indeed a 

 literary effort of which both author and publishers may 

 well be proud. 



It has been Prof. Bower's, intention to present not 

 mly a reasoned statement of the relative value of the 

 riteria on which the systematic grouping of the ferns 

 must for long be based, but also to indicate for them 

 probable relationships with other primitive phyla, and 

 thus to render the comparative study of their phylesis 

 ' ontributory to still wider views on the descent of land- 

 iiving organisms. The present volume deals primarily 

 with the criteria of systematic comparison themselves. 



NO. 2814, VOL. 112] 



Presenting as it does for the first time in the history ~of 

 the literature of plant-systematics a fully co-ordinated 

 and closely reasoned statement on the values ascribed 

 to the characters considered, it forms a conspicuous 

 landmark in the progress of systematic thought and 

 writing. 



On the criteria drawn from the widest study of 

 external form, cellular segmentation, leaf venation, 

 the vascular system of the shoot, dermal appendages, 

 the position and structure of the sorus, indusial pro- 

 tections, the characters of the sporangia and spores, 

 spore-output, the morphology of the prothallus, the 

 position and structure of the sexual organs, and the 

 embryology of the sporophyte, the author's rebuilding 

 of the systematics of the ferns in the second volume 

 will largely rest. It is not too much to say that in this 

 book Prof. Bower has valiantly endeavoured to formu- 

 late anew standards of phyletic comparison whereby 

 a new and more reasonable order will arise out of the 

 chaos to which fern-systematics had been reduced. 

 A chapter is devoted to each criterion considered, and 

 a comprehensive and carefully chosen bibliography is 

 in each case appended, chosen with the author's full 

 knowledge of the literature of his subject. 



Varied as are the ways whereby we arrive at our 

 conclusions, our most absorbing interest, and indeed our 

 ultimate aim in the study of living organisms, lie in the 

 determination of their inter-relationships. It is safe 

 to assert that for the past generation the only method 

 open for a reasonable understanding of the phylesis 

 of any group of organisms has been the morpho- 

 logical method. This Prof. Bower has followed with 

 admirable persistency and foresight throughout a 

 lifetime of active research. That the results have 

 fully justified the means cannot for a moment be 

 doubted. To arrive at a reasonable grouping of the 

 ferns from the comparative study of their characters of 

 form, structure, and reproduction has been the avowed 

 aim of the author for many years. That the meaning 

 of the characters themselves expressed in form and 

 structure still escapes us will be readily granted. For 

 many who have not followed his phyletic method, the 

 absence of a final interpretation of structural characters 

 may seem cause for delay in the acceptance of the 

 relative value of the characters discussed, and indeed 

 of any wide application of the conceptions of the 

 relative primitiveness or advancedness at which the 

 author has arrived. Instinctively, one revolts against 

 the idea that hairs must be the expressions of relatively 

 primitive characters, while scales, on the other hand, 

 are indicative of advance, even though the author has 

 conducted with consummate skill a special pleading of 

 the case, supported on broad grounds by the illuminat- 

 ing evidence of fossil-history. That priniiti\e ferns 



