PREFACE TO SECOND EDITION 



111 preparing this edition of the book the author has attempted 

 to bring the subject matter as nearly up to date as possible and 

 to rearrange the material so that it can be outlined by the student 

 more readily. This has necessitated rearrangement of the chapters 

 as well as of their contents in many instances. AVhere it has been 

 deemed advisable, material has been deleted. Two new chapters, 

 one on the reticulo-endothelial system and the other on serum 

 reactions, have been added. The chapter on colloids has been placed 

 in the Appendix where it can be referred to by students unfamiliar 

 with the elementary chemistry of colloids. The chapters dealing 

 with the serology of syphilis have been revised in accordance with 

 the procedures approved by the "Committee on the Need of Ad- 

 herence to Conventional Technique in the Performance of Reliable 

 Serologic Tests for Syphilis" appointed by the Surgeon-General 

 of the United States Public Health Service. 



The author is very appreciative of the helpful suggestions given 

 him by Dr. K. Landsteiner, Dr. W. J. Nungester and others work- 

 ing in the field of immunology. The many constructive criticisms 

 given by reviewers of the first edition have been of considerable 

 help in this revision. 



As in the preparation of the first edition, a number of colleagues 

 and members of my family have rendered material assistance in 

 Ihe preparation of the manuscript of this revision. Among these, 

 Dr. C. M. Downs, Mr. Harold Nelson, and my Avife have been 

 extremely helpful. 



Noble Pierce Sherwood. 



Lawrence, Kansa?. 



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