PREFACE. 



THE progress of our knowledge relating to the bacteria has been 

 so rapid and the literature of the subject is now so extensive that it 

 is no small task to keep pace with this progress, even when one has 

 the literature at hand and devotes a large share of his time to bac- 

 teriological studies. Fortunately, recent researches in this depart- 

 ment of science have been largely made by exact methods and by 

 trained investigators, and the results can be accepted as well estab- 

 lished. A manual of bacteriology, therefore, which fairly represents 

 the present state of knowledge, will consist largely of a statement of 

 facts established by experimental data, and cannot fail to be of value 

 to physicians and to advanced students of bacteriology as a work of 

 reference. The present volume is an attempt to supply such a 

 manual, and at the same time a text book of bacteriology for stu- 

 dents and guide for laboratory work. That portion of the book 

 which is printed in large type will, it is hoped, be found to give an 

 accurate and sufficiently extended account of the most important 

 pathogenic bacteria, and of bacteriological technology, to serve as a 

 text book for medical students and others interested in this depart- 

 ment of science. The descriptions of non-pathogenic bacteria, and 

 of the less important or imperfectly described species of pathogenic 

 bacteria, are given in smaller type. In the preparation of this man- 

 ual various text books in foreign languages have been consulted, and 

 I am especially indebted to the works of Fliigge, of Baumgarten, 

 and of Eisenberg. But the descriptions of species and experimental 

 data have been very largely taken from original memoirs. ' The 

 illustrations also are to a considerable extent reproductions from 

 the original papars of those engaged in research work. 



NKW YORK, April 1st, 1892. 



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