vi PREFACE TO THE SEVENTH EDITION 



In Chapter X., which deals with the Typhoid-Colon 

 group, Winslow, Klizler and Rothberg's classification of 

 the group is given, and many new details are added in 

 the sections on typhoid and paratyphoid fevers and 

 dysentery, e.g., Para C infections and the Sonne group of 

 dysentery organisms. 



In Chapter XII. the subject of Pneumonia has been 

 largely re-written and the account of Epidemic Influenza 

 revised. 



The descriptions of the pathogenic anaerobes have 

 likewise been re-cast and many additions made. 



Under Typhus Fever an account is given of the 

 remarkable Weil-Felix reaction. 



Noguchi's researches on yellow fever and new work on 

 various pathogenic spirochaetes have been added. A 

 section on Encephalitis lethargica is now included. 



The section on the Wassermann reaction has been 

 entirely re- written, the Fildes and Mclntosh method being 

 that now described. 



The subject of food-poisoning has been re-written, and 

 a new account of Botulism incorporated. 



My best thanks are due for much assistance in the 

 revision of the proof-sheets to my friend and colleague, 

 Dr. Frank Taylor, and to my son, Mr. Allan Hewlett. 



R. T. H. 



UNIVERSITY OF LONDON, 

 KING'S COLLEGE. 



