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BIOLOGY 

 LIBRARY 



PKEFACE TO THE ENGLISH EDITION. 



So far as the aim and scope of the book are concerned they are sufficiently 

 described in the Author's prefaces. It remains to be said that the lack of 

 a similar text book in English, at once sufficiently simple to put into the 

 hands of the beginner and at the same time sufficiently advanced to be of 

 service to the more experienced observer, together with the evident popularity 

 of Dr. Besson's work in French speaking countries, seems to be sufficient 

 justification for preparing the present translation. 



A mere translation however of a book dealing with so rapidly advancing 

 a science as Microbiology would have been hardly satisfactory, hence an 

 attempt has been made to bring it up to date by incorporating matter which 

 has appeared since the French edition went to press. 



As regards the translation itself the original text has been followed as closely 

 as possible, but the aim throughout has been to reproduce the sense rather 

 than the actual words. 



The alterations which have been made may be included under two heads, 

 namely : alterations in the text and alterations in the arrangement of the 

 text. With two exceptions the whole of the French text has been followed. 

 In Chap. VII. the theory of the Microscope has been rewritten as, generally 

 speaking, the Student seems to possess but a very limited knowledge of the 

 instrument and it was thought that an amplification of the French text 

 would be useful. I wish to thank Mr. A. S. Percival, Senior Surgeon to the 

 Eye Infirmary, Newcastle upon Tyne, for the help he has given me in this 

 part of the subject. Chaps. XXV., XXVL, and XXVII. dealing with the 

 Paratyphoid bacilli have also been rewritten in view of the work of the Royal 

 Army Medical Corps in India and of Dr. F. A. Bainbridge in England. 



There are many notes and additions. Thus for instance it was found 

 necessary to incorporate the important results obtained by the Royal Com- 

 mission on Tuberculosis. All such notes and additions are clearly indicated 

 either by a footnote or by being enclosed withia square brackets. It should 

 be said also that in a few cases where the authorities were in favour of a 

 different nomenclature from that until recently in use the new names have 

 been substituted thus Discomyces appears as the generic name in place of 

 Streptothrix. 



