VI PREFACE 



been indicated for the first time in this volume by M. G. Sevag, 

 Immuno-Catalysis. 



In Sevag's treatment of immuno-catalysis we discern that enzyme, 

 substrate, and specifically inhibitive reaction products, have their 

 respective counterparts in antigen, the antibody precursors, and spe- 

 cific antibodies. This is no mere analogy, for antigens in truth do 

 determine the specificity of newly forming antibodies by a catalytic 

 mechanism; many protein enzymes have been proved to be antigenic; 

 the chemical configurations upon which specificity depends in enzyme 

 and immune reactions are often analogous or identical. 



Specialists either in enzymology or immunology will find the first 

 three sections of the book a reservoir of experimental fact, considered 

 with insight and woven together in a remarkable synthesis. 



The enzymes of plants which are pharmacologically active, the 

 enzymes of snake venoms and the enzymes of pathogenic bacteria are 

 considered in detail with reference to their chemical activities in vitro, 

 their pharmacodynamic actions in vivo, and with respect to specific 

 immunity against them. 



Consideration of this array of data, which is little known to most 

 students of immunity and of infectious disease, leads the reader to the 

 conclusion that many diverse symptoms and lesions of infectious dis- 

 ease may find their explanation in terms of the action of biocatalysts 

 of the parasite which can alter vital substrates of the host. Much of 

 the pathological symptomatology of bacterial and viral disease may thus 

 ultimately come to be understood as special manifestations of enzyme 

 action. Chemical and pharmacological studies with the lecithinases, 

 proteases and nucleases of snake venoms and of those associated with 

 pathogenic Clostridia, and studies of hyaluronidase and fibrinolysin 

 afford striking pertinent cases. 



Success in research and success in teaching are in no small part 

 dependent upon discernment of the interrelationships of things; the 

 deeper the insight into phenomena which seem superficially unrelated, 

 the more clearly they may often be perceived to rest upon more funda- 

 mental, general laws of matter and energy. Teachers and investigators 

 dealing with biochemistry, with bacteriology and immunity and with 

 the mechanisms of infectious disease will, I believe, find in this in- 

 formative book an expanded horizon and a challenge to further 

 investigations. 



