vi PREFACE TO THE ENGLISH EDITION 



The arrangement of the text in the translation varies from that of the 

 original in some respects. In the first place the subject matter has been 

 divided into seven Parts instead of three. Secondly, the arrangement of 

 the Parts has been subjected to some modification. To take the Bacteria 

 for example it seemed that in a book intended for use in the laboratory it 

 might be an advantage if these organisms were arranged morphologically 

 and then subdivided according to their staining reactions and cultural charac- 

 teristics. The plan adopted can be readily seen by a reference to the Table 

 of Contents. Of course no classification is perfect and therefore free from 

 criticism but after a good deal of consideration it was felt that practical 

 usefulness merited the attempt. 



Reference to any particular point will present, I hope, no difficulty. In 

 addition to an Index and a very full Table of Contents, a summary of the 

 subject matter heads the various Chapters. These of course are quite inde- 

 pendent of the French edition. 



The illustrations have been carefully revised. Many of them are new 

 though illustrating familiar subjects and were drawn by my former laboratory 

 attendant, Mr. H. Boot, under my supervision from preparations in my 

 laboratory. Some were drawn by Mr. Richard Muir. For others I am 

 indebted to the courtesy of the Controller of His Majesty's Stationery Office, 

 of Professor G. H. F. Nuttall, F.R.S., of Dr. H. G. Adamson, and of the 

 Publishers of Mense's Handbuch der Tropenkrankheiten. Miss M. V. Lebour, 

 M.Sc. of the Zoological Department of the University of Leeds kindly 

 undertook to redraw the whole of the line drawings. 



In the preparation of this translation I wish to acknowledge my very par- 

 ticular indebtedness to Professor G. A. Lebour, M.A., D.Sc. who has given 

 me at all times most invaluable assistance. To my former colleague Mr. 

 C. F. Fox who had charge of the records of the Royal Commission on Tubercu- 

 losis I owe many thanks for the considerable care with which he undertook 

 the thankless task of reading over the whole of the MS. before it went to 

 press and for revising the proofs. 



H. J. HUTCHENS. 



Newcastle upon Tyne, 



March 3lst, 1913. 



