PREFACE 



Bacteriology is so recent a science that from its 

 infancy it has been able to record by the aid of 

 photography the forms and characters of the micro- 

 organisms discovered, and the pathological changes 

 produced by them in the tissues. At an early date 

 Koch insisted on the value of a photographic record 

 as a convincing proof of the reality and accuracy of 

 the descriptions. For the most part, proof of this 

 kind is no longer needed, but more and more has 

 photography taken the place of the diagram or the 

 drawing. It is in Bacteriology that illustration by 

 photography is perhaps more satisfactory than in 

 any other branch of pathology. Numerous are the 

 excellent illustrations occurring in works on this 

 subject, but these plates, even when not deprived of 

 some of the excellence of the original negatives by 

 the process of reproduction, are generally scattered 

 and fragmentary recbrds of particular appearances. 

 The Atlas der Bakterienkunde by Frankel and 



