PREFACE 



THIS book has its origin in a monograph by 

 Professor Wassermann, a translation of which was 

 published by the author in 1904 under the title 

 " Immune Sera." While much of the material con- 

 tained in that book will be found in the present 

 volume, it has been deemed necessary to discuss 

 more fully the original topics, and to widen the 

 scope of the book by adding chapters on snake 

 venoms and their antisera, agglutinins, opsonins, 

 and serum sickness. The author gratefully ac- 

 knowledges his indebtedness to Dr. W. H. Park for 

 valuable suggestions in the preparation of the book. 



NEW YORK, Sept. i, 1907. 



NOTE TO THIRD EDITION 



IN response to a number of inquiries, the author 

 has added a chapter dealing with the serum diagno- 

 sis of syphilis. This concerns mainly the test de- 

 vised by Wassermann and subsequently modified 

 by various authors, though a brief description of 

 the Porges-Meier test is also included. Through 

 the courtesy of Dr. Noguchi, the author is also 

 able to present a note on a simple, as yet unpub- 

 lished, test devised by that investigator. 



NEW YORK, July 15, 1908. 



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