REVIEWS 347 



to accord with the postulates of Relativity, followed by the treatment of electro- 

 magnetic phenomena. 



The book only deals with the "restricted" Relativity of two systems of 

 reference in uniform relative motion. No account is given of the more recent 

 generalised form of it as applied by Einstein and others to the problems of 

 gravitation. 



J. R. 



CHEMISTRY 



Biochemical Catalysis in Life and Industry. Proteolytic Enzymes. By 



Jean Effront. [Pp. xii + 752.] (New York : John Wiley & Sons ; 

 London : Chapman & Hall, 1917. Price 25s. net.) 



This book, which is translated from the French by Samuel C. Prescott, Professor 

 of Industrial Microbiology at the Massachusetts Institute of Technology, forms 

 in a sense a companion volume to Prof. Effront's " Enzymes and Their Applications," 

 which was published several years ago. The present volume opens with an 

 introductory chapter on the general properties of colloids and enzymes ; the rest 

 of the book is divided into six parts, each of which is subdivided into chapters 

 or sections according to size. Part I is devoted to coagulating enzymes, and 

 contains a comprehensive account of the various views concerning the origin and 

 mechanism of the blood-clotting enzyme Thrombin, together with the experimental 

 evidence on which these views are based ; then follow a couple of pages on 

 Myosinase, the name given to the enzyme of somewhat doubtful existence, which, 

 according to a few authors, whose views are not universally accepted, is supposed 

 to coagulate muscle plasma. Part I is brought to an end by a chapter on Rennet 

 extending over some fifty pages, in which are described in some detail the prep- 

 aration and properties of this enzyme, and the influence upon its action of the 

 reaction of the medium. With regard to the question of the identity of different 

 rennets, it is shown that the differences in properties of individual samples are 

 much influenced by the presence of impurities connected with their source of 

 origin ; although it is generally held that the various rennets are not identical, 

 it is difficult to speak with certainty on this subject while the methods of isolating 

 enzymes are so imperfect ; even the purest samples are contaminated with other 

 substances which may influence their activity favourably or otherwise. 



Part II is devoted to Pepsin; the subject is fully dealt with from the point 

 of view both of the conditions under which the enzyme acts and the products 

 which it forms. The question as to the possible identity of rennet with pepsin 

 is complicated by the fact that the two are always associated with each other ; 

 the supporters of the view that the two enzymes are in reality one consider that 

 the enzyme exerts either a coagulating or a peptonising action according to the 

 condition of the medium ; in the author's opinion the question will not be settled 

 until one or other of these enzymes is found occurring alone in a plant, or until 

 an antienzyme is prepared by immunisation, which is specific for either rennet or 

 pepsin. The second chapter of Part II, entitled " Reversible Action of Enzymes," 

 has a somewhat incomplete bibliography, with a number of important omissions. 



Part III deals with pancreatic Trypsin and a number of similar enzymes from 

 vegetable sources, and also with immunisation and antibodies. 



Parts IV and V are devoted to Erepsin and Amidases respectively ; while 

 Part VI, occupying about one-quarter of the whole book, gives an account of the 

 numerous applications of enzymes to medical science and industry ; this part is, 



