PREFACE FOE SECOND EDITION 



THE revision for the second edition of this book has been made 

 under difficult conditions since, for the greater part of the time 

 immediately preceding its issue, the writer was removed from the 

 facilities of libraries and journal files. There are, in consequence, 

 many spots, here and there, which have not been as thoroughly 

 scrutinized as we would wish. Nevertheless, all the important 

 changes necessitated by the lapse of time since its first printing 

 have been made and much new material added. 



The chapters on anaphylaxis have been almost completely re- 

 written, as demanded by changes of view resulting from the work 

 of others, as well as our own. The Abderhalden reaction having 

 been proved to be an interesting camouflage, the material contained 

 in this section has been revised and the more recent work on 

 enzymes added. The development of conceptions of non-specific 

 serum and cellular reactions has been discussed especially in con- 

 nection with the recent important work of Jobling and Peterson. 

 A section of Immunity in Syphilis has been added, based on our 

 own studies with Hopkins and McBurney, and the chapter dealing 

 with specific therapy in various infections has been revised and 

 expanded. In addition to this, many minor alterations and com- 

 ments have been made, paragraphs omitted and inserted. 



Throughout, there has been no attempt to make the book what is 

 generally known as a "practical manual." There are many books 

 which devote themselves particularly to the instruction of workers 

 in measurements and manipulations, and we believe now, as we did 

 before, that the present volume would prove most useful by present- 

 ing in detail the fundamental principles underlying the biology of 

 infectious diseases. Such treatment of the subject is, in our opinion, 

 indispensable as a preliminary training for those who deal with in- 

 fection in the clinic or the laboratory, and the material on which 

 the book is based is included, at present, in lectures required of 

 second year students at the Columbia School of Medicine and is a 

 prerequisite to further practical training in Serology. 



HANS ZINSSER. 



