PREFACE TO THE 

 FIFTH EDITION 



IN this edition while the plan of the book remains sub- 

 stantially the same, the text has been completely revised. 

 Many alterations and additions have been made in the 

 preliminary chapters dealing with the structure and 

 classification of micro-organisms and with the methods 

 of cultivation, isolation, and staining. The chapter on 

 the side- chain theory and immunity reactions has been 

 extended and new details respecting anaphylaxis inserted. 

 Considerable changes have been effected in the chapters 

 dealing with particular micro-organisms, e.g. the Strepto- 

 cocci, Anthrax, Tubercle, and Leprosy bacilli, typhoid 

 fever, and cholera. More space is devoted to the Moulds, 

 and the subjects of Sporotrichosis and Thrush have been 

 transferred to this section. 



In the chapter dealing with the Protozoa the cultivation 

 of the Spirochaetes has been inserted, mention is made 

 of the Luetin reaction, and the account of the Wasser- 

 mann reaction and the description of the life history of 

 the rabbit Coccidium have been re-written. The pages 

 dealing with Hydrophobia, Vaccinia, and Malignant 

 Disease have been revised, and new sections on Pellagra 

 and Rat-bite Disease have been inserted. Further details 



