PREFACE TO THE SIXTH EDITION. 



WE have taken advantage of the publication of a new edition to 

 make again a careful revision of the whole work. During the 

 past two years definite additions to our knowledge have been 

 made in various departments, and in dealing with these we have 

 directed attention chiefly to those results which appear to us 

 likely to stand the test of future inquiry. In view of our 

 purpose to produce a book which will be primarily useful to 

 students and practitioners of medicine, any increase in its size is 

 undesirable; but the growing recognition of the importance of 

 the fungi as disease-producing organisms has led us to add a 

 chapter dealing with this subject. For assistance in its prepara- 

 tion, it gives us pleasure to record our indebtedness to Professor 

 Percy Groom of the Imperial College of Science, London, and to 

 Dr. Cranston Low, Edinburgh. A new section on the bacteriology 

 of milk has also been added. A number of new micro-photographs 

 have been inserted throughout the text. 



June 1913. >> 



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