^PREFACE TO THE FIRST EDITION 



Immunity, in its present state of development, 

 with its manifold new terms and special methods 

 of experimentation, is a subject which appears 

 difficult to one who has not studied the newer 

 literature assiduously and grown into a knowledge 

 of the conditions through actual work in the lab- 

 oratory. Much of the literature is technical in 

 character and appears in journals not commonly 

 found in the hands of the physician and student. 

 Much of it also is comparatively recent, and its 

 "essence" has not yet appeared in books which are 

 in general use. The literature of immunity, more- 

 over, grows so amazingly that the analysis even of 

 current works is a task of no mean proportions. 



At the same time, the subject is one of great 

 interest and importance, and there exists a gen- 

 eral wish, frequently expressed, to know more 

 about the recent advances and the conditions which 

 have operated against the success^of serum therapy 

 on a broader scale. 



The editor of The Journal of tlie American 

 Medical Association, appreciating the need which 

 seemed to exist, requested me to prepare a series 

 of articles on the subject of "Immunity/' which 

 should present the general principles and the 

 important theories and facts, in as simple a man- 

 ner as possible. These articles appeared from week 

 to week during 1905 in The Journal of the Amer- 

 ican Medical Association, and after revision, and 



