PREFACE TO THE SEVENTH EDITION 



IN this new edition the text has been subjected to 

 extensive revision and much of the book has been re- 

 written. The following summary indicates some of the 

 principal alterations and additions : - 



In the earlier pages the salient features of the American 

 Committee's suggestions on the classification of bacteria 

 have been incorporated. 



In the preparation of culture media the question of 

 hydrogen ion concentration is introduced and reference 

 made to new indicators and the adjustment of reaction 

 therewith. 



Among methods, Mutch's single-cell culture and modi- 

 fications of Gram's method are introduced. 



The section on the microscope has been entirely re- 

 written, and the method of dark-ground illumination is 

 fully described. 



Many alterations and additions have been made in the 

 sections dealing with anti-bodies and serological reactions, 

 particularly haemolysis, complement fixation and agglu- 

 tination, and a description of Garrow's method has been 

 added to the last-named. 



Chapter VI., dealing with septic diseases, has been 

 re-arranged and partly re- written, and Holman's classifica- 

 tion of the Streptococci has been introduced. 



Many minor alterations have been made in the subjects 

 of anthrax, diphtheria, and tuberculosis. 



