viii PREFACE TO THE FOURTH EDITION. 



of man and animals will be not only of scientific interest, 

 but of practical value to Medical Officers of Health and 

 Veterinary Inspectors. 



I have divided the book into three parts. Part I. is 

 mainly technical, and includes the most recent methods 

 employed in studying bacteria and investigating the etiology 

 of disease. Part II. deals with infective diseases and the 

 bacteria associated with them. Any clinical or pathological 

 evidence which may help to throw light on the nature and 

 origin of the contagia is taken into account. The most 

 effectual measures for stamping out these diseases are 

 referred to, as they are intimately connected with a 

 knowledge of the life-history of micro-organisms. Part III. 

 contains] descriptions of about five hundred bacteria. Many 

 are of no practical importance and of very little scientific- 

 interest, but a text-book for the laboratory cannot be con- 

 sidered complete unless an account is given of all bacteria 

 which have been more or less completely investigated. I 

 have endeavoured to refer to the original descriptions and 

 to verify them by comparison with actual cultivations, but 

 in a very great number of instances this has been quite 

 impossible, and I desire to acknowledge the assistance I have 

 received from the works of several authors, especially those 

 of Fliigge, Fraukel, Eisenberg, Baumgarten, Frankland, 

 Sternberg, Lehmann and Neumann. 



If^have rearranged the bibliography according to the 

 chapters^and the names of authors are given in alphabetical 

 order. With the aid of the current numbers of the Annales 

 <le rinstitut Pasteur, the Zeitschrift fur Hygiene, the 

 Centralblatt fur Bakteriologie und Parasitenkunde^ and the 

 Journal of Comparative Pathology and Bacteriology, it is 

 possible to become acquainted with the most recent litera- 

 ture of the subject. 



Many of the coloured plates illustrating the last edition 

 have not been reproduced. Those substituted for them have 

 been drawn from my own preparations, and most of them 



