PREFACE vii 



may serve to show, when compared with the speci- 

 mens actually in the hands of the student, the 

 direction and extent of the variation. 



Descriptions of the methods employed in the 

 preparation of the specimens have been omitted, as 

 the student will necessarily possess some recognised 

 text-book or work on practical bacteriology in which 

 descriptions of methods are more fully and appro- 

 priately treated than they could be in such a work 

 as the present. A statement of the method used 

 in the preparation of each specimen forms part, 

 however, of the short description affixed to the illus- 

 trations. 



On the other hand, a short description of the 

 photographic methods and apparatus employed 

 would seem to find a fitting place as an intro- 

 duction. 



The number of illustrations is of necessity limited, 

 and while trying to associate the importance of the 

 subject with the completeness of the series, yet in 

 some instances, such as tuberculosis, it is felt that 

 the subject, so far at least as the histology of 

 tubercle is concerned, is so fully 'treated and illus- 

 trated in text-books that it is needless to multiply 

 representations by adding sections of tubercular 

 organs. 



