iv PREFACE TO THE SECOND EDITION. 



infection is hereditary, thereby enlarging our 

 understanding of the part insects may take as 

 carriers of disease; he demonstrated that the 

 typhus fever of the Mexican plateau, tabardillo, is 

 carried by the body louse (Pediculm vestimenii). 

 and the results of his work on this disease, which 

 he had only just begun, will be of fundamental 

 significance in its prevention and in all future 

 investigation as to its cause and nature. In his 

 death "on the firing line" we lost an investigator 

 of the first rank whose name through these achieve- 

 ments will live in the history of medical science. 



When the papers and manuscripts left by Dr. 

 Eicketts came to be examined it was found that 

 while the work of revision and enlargement of this 

 book was very far from complete yet he had car- 

 ried it so far that it seemed unwise not to attempt 

 to carry it through to completion. Fortunately 

 Dr. George F. Dick was willing to take up the 

 unfinished task, which proved to be a much larger 

 one than was anticipated for the reason that, in 

 addition to completing the revision and adding a 

 considerable amount of new material, it was neces- 

 sary also to secure proper coordination and balance 

 between the different parts of the book. 



The book is now divided into an introduction 

 and three parts instead of two as in the first edi- 

 tion. The Introduction and Part I were prepared 

 by Dr. Eicketts and the chapters on "Sources of 

 Pathogenic Micro-organisms" and on "Special 

 Features of Infection" are new. Part II contains 

 new chapters on "Complement-Deviation," "Opso- 

 nins," and "Anaphylaxis," and Part III chapters 

 on "Epidemic Poliomyelitis," "^oma," and "Kala- 

 Azar," all by Dr. Dick. The old chapters in Parts 



