582 



NA TURE 



[April 24, 1902 



the present book. Such a work need not necessarily 

 greatly exceed the " Leitfaden " in bulk, for the classifica- 

 tions, excellent though they are, and the general summary 

 of the different groups might safely be left to the lecturer 

 or text-book. This, together with the omission of some 

 of the less important groups, would allow space for more 

 practical instruction in manipulation and for a some- 

 what fuller treatment of most of the different types 

 described, more especially of those of the vertebrates. 



On the whole, it may be said that the present work 

 bears the stamp of originality ; the style is clear and the 

 descriptions are terse and generally accurate, and if in a 

 future edition Dr. Kiikenthal should see fit to remodel 

 his book in such a manner as suggested, it would be 

 welcomed in our colleges as a valuable and much-needed 

 aid to the beginner in the laboratory. E. W. 



FERMENTS AND FERMENTA TION. 

 Ferments and their Actions. By Carl Oppenheimer, 

 M.D., Ph.D., and translated and amended by C. 

 Ainsworth Mitchell, B.A., F.I.C. Pp. xii -t- 343. 

 (London : C. Griffin and Co., Ltd., igoi.) Price 

 7j. bd. net. 



THERE are few subjects more interesting and at 

 the same time more difficult than the study of 

 ferments and their actions. But many students, and not 

 a few original workers, shrink from the study of ferments 

 owing to the great complexity of the subject. A book, 

 therefore, which aims at treating the subject in a concise 

 and intelligible manner must inevitably attract a wide 

 class of readers. 



The author very properly points out that it is im- 

 possible to understand any of the problems relating to 

 fermentation unless there be formulated some definition 

 of a ferment per sc and some simple conception of the 

 process of fermentation. With this object, in the 

 second chapter the writer gives us what he considers a 

 simple definition of the notion ferment : — 



"A ferment is the material substratum of a peculiar 

 form of energy, which is produced by living cells and 

 adheres more or less firmly to them without having its 

 activity bound up with the vital process as such ; this 

 energy is in a condition to bring; about the liberation of 

 latent (potential) energy of chemical substances and its 

 conversion into kinetic energy (heat, light), in such 

 manner that the chemical substance is so changed in 

 the process that the new substance or the sum of the 

 new substances produced possesses a smaller potential 

 energy [i.e. a smaller heat of combustion) than the 

 original substance." 



It must be confessed that, however scientifically per- 

 fect this definition may seem to be, it will not impress 

 the average reader with the idea of its simplicity. But 

 the distinguished author goes on to elucidate the different 

 heads of this definition, and in so doing makes clear 

 even to the lay reader many vital points bearing on this 

 difficult subject. 



The following frank acknowledgment of the ignorance 

 which underlies all our conceptions of the ways and 

 means by which fermentative processes develop their 

 activity is worth quoting in full : — 



"We must simply resolve to regard fermentative 

 actions as special phenomena of the ominous 'catalytic' 

 NO. 1695, VOL. 65] 



processes from which their differentiation is required by 

 the fact that they are produced by living cells. Cata- 

 lytic action is nothing more than a scheme of despair 

 under which we may group chemical reactions which, 

 while possessing a certain similarity in their course, 

 cannot, without further knowledge, be explained by our 

 simple chemical theories. With the advance of our 

 knowledge, we have naturally been able to assign many 

 phenomena which were formerly regarded as catalytic to 

 simpler chemical laws, so that this useful idea has 

 undergone a considerable limitation in its applicability. 

 At the same time we must not forget that in its essence 

 even the theory of simple chemical decompositions and 

 of chemical affinity is, as regards our theoretical know- 

 ledge, only one vast enigma ; that we have only been 

 much longer accustomed to deal with these conceptions 

 as indispensable fundamental axioms without being able 

 to approach them otherwise than metaphysically, which 

 also holds good in a still wider sense of the conceptions 

 of matter and force in general." 



Chapter iii., on the chemical nature of ferments, is 

 well worth the most careful perusal. It is the fault of 

 the subject, not of the writer, that it makes stiff reading. 

 In this chapter the author points out the uselessness of 

 such vague expressions, which lead nowhere, as that 

 there are in ferments "fragments of protoplasm" 

 endowed with " residues of vital force." Gautier's 

 dissolved cell hypothesis is very ably discussed. 



The influence of external factors on the action of 

 ferments is concisely dealt with in chapter iv., and 

 chapter v., on the mode of action of ferments, is perhaps 

 the most interesting in a book all of which is full of 

 matter of absorbing interest and importance. 



But it is impossible within the scope of this short 

 review to touch on more than a fraction of the points 

 in the work, which will repay study by both the layman 

 and the expert in this subject. 



A. C. HOU.STON. 



OUR BOOK SHELF. 



Civil Engitiecring as applied in Construction. By 

 Leveson F. Vernon Harcourt. " Longmans' Engineer- 

 ing Series." Pp. xv -\- 624 ; with 36S illustrations. 

 (London, New York and Bombay : Longmans, Green 

 and Co., 1902.) Price 14J. net. 

 This book, as the author states in the preface, consists 

 of a concise grouping together of the various branches of 

 constructive civil engineering. 



A book that attempts to deal in a single volume with 

 the vast range of subjects embraced in civil engineering 

 must necessarily be more in the nature of an encyclopaedia 

 than a series of treatises on the subjects dealt with ; and 

 the descriptions of the works selected as examples are, 

 therefore, necessarily limited to as small a space as is 

 possible for the elucidation of the various subjects, and 

 for indicating the practice followed in the execution of 

 constructive works ; but what is given is of a thoroughly 

 practical character, and the subjects are very fully illus- 

 trated. The author has not taken up space by dealing 

 with theories, or by giving elaborate formuht. 



The information given has been derived to a very large 

 extent from Proceedings of the Institution of Civil En- 

 gineers, of which the author gives full acknowledgment. 



The book should be of great use to an engineer when 

 called upon to deal with constructive works of a character 

 that he has not had previous experience of, as indicating 

 the various ways in which constructive requirements have 

 been treated. To students of engineering it will be of 

 value in directing attention to the principles forming the 



