AUTHOR'S PREFACE, 



During recent years that part of biology which 

 concerns itself with the reactions resulting from the 

 injection of organic constituents of one animal 

 into the body of another has been worked up ex- 

 perimentally with great enthusiasm. This field, 

 which in the beginning seemed to possess only a 

 purely scientific interest, has now yielded numer- 

 ous analogies to the results obtained in the experi- 

 mental study of natural and artificial immunity 

 against infectious diseases. Furthermore, the re- 

 sults of these investigations have been found ap- 

 plicable to many clinical questions, as well as to 

 certain other problems of every-day life. It is 

 with pleasure, therefore, that I heed the request of 

 one of the editors of these "Clinical Lectures" 

 [von Bergman] to present these highly interesting 

 results to the medical profession at large. It is not 

 my purpose to give the details of the many, oft- 

 times complicated experiments undertaken by vari- 

 ous authors to support or refute different theories. 

 The following sketch is intended rather to intro- 

 duce my colleagues to the essentials of the subject. 



A. W. 



