PREFACE 



Treatment of individual diseases with medicines or by methods having 

 a selective curative action has until recently been limited. With the establish- 

 ment of the germ theory of certain diseases and the development of informa- 

 tion concerning immunity, new methods of specific treatment were made pos- 

 sible and are now practiced under the name of serum and vaccine therapy. 

 As might be expected, the medical profession has been much interested in these 

 methods of treatment, and applied them whenever possible. The develop- 

 ment of vaccine and serum therapy has been slow, the methods have had to 

 be revised and in some cases the results obtained have been found to be other- 

 wise than was at first expected. Because of this, much confusion has arisen. 

 The practitioner has not been able to keep pace with the developments and 

 literature on these subjects, and finally has been forced to depend on the state- 

 ments and recommendations coming from serum and vaccine laboratories, 

 enthusiasts and ever; exploiters. 



In this work fin attempt has been made to state concisely and accurately 

 the present knowledge concerning vaccines and immune sera. An effort has 

 been made to establish theoretical and experimental evidence as well as clin- 

 ical application of the specific treatment of bacterial diseases. To accomplish 

 this, some space is given to infections in general, the theories of immunity, 

 with especial emphasis on the opsonic theory of immunity, as well as the par- 

 ticular methods of vaccine and serum therapy. 



Considerable space has been given to opsonins, the opsonic index and the 

 importance of opsonins in health and disease. This has been done because 

 since 1904 no subject has appeared more prominently or frequently in medical 

 literature than that concerning opsonins, opsonic immunity, and bacterial 

 vaccines. In the first presentations of discoveries on this form of immunity 

 and specific treatment of bacterial diseases, great possibilities were promised. 

 Methods, which would, according to Wright, give uniform success in treat- 

 ment of the large class of bacterial infections and diseases, naturally received 

 immediate and general attention by the medical world and were at once quite 

 generally applied. This has been followed by much indiscriminate and un- 

 scientific use of these methods of specific treatment so that in the minds of 



