PEEFACE TO THE FIFTH FRENCH EDITION. 



EECENT advances in Microbiology have necessitated an entire revision of 

 the text. While still retaining its original form most of the chapters have 

 been recast and much new matter has been incorporated. 



The plan adopted when the book was first written of omitting all discussion 

 upon matters of theory has been adhered to but it has nevertheless been 

 thought desirable to include a Chapter on Immunity and the Properties 

 of Immune Serums. The object of this has been to explain as clearly and 

 simply as possible the principles underlying the phenomena of agglutination, 

 of the fixation of the complement and the opsonic index and to describe the 

 practical details in such a manner as to enable the Student to become familiar 

 with the technique employed in these delicate investigations and so be in a 

 position to appreciate the more detailed monographs. 



In view of its importance in clinical diagnosis a description of the Ultra- 

 microscope has been included. 



Numerous additions and alterations have been made in the second Part. 

 Most of the chapters have been supplemented. The serum treatment of 

 Dysentery and of meningococcal Meningitis has been described as fully as 

 was consistent with the scope of the work. The anaerobic micro-organisms, 

 the paratyphoid bacilli, Sporotrichosis, Syphilis, etc. are all subjects of 

 additions while many modifications have been introduced into the descrip- 

 tion and classification of the parasitic Protozoa, especially the Piroplasmata, 

 Leishmania and Trypanosomala. 



As in former editions the sole object has been to write a clear and concise 

 account of each subject and one which will be abreast of recent knowledge 

 retaining at the same time those characteristic features of the book which 

 have been the subject of favourable comment both here and abroad. 



A. BESSON. 

 15^ May, 1911. 



