CHAPTER I 

 Introductory 



SCOPE OF THE MANUAL 



There has sometimes been misunderstanding as to the sense in which 

 the Committee on Bacteriological Technic uses the expression "pure 

 culture study of bacteria." It is occasionally thought that such an 

 expression would cover nearly the whole field of bacteriological technic. 

 On the other hand, the definition of pure culture study of bacteria 

 which has been drawn up by the committee is the study of bacterial cul- 

 tures with the object of learning their characteristics and behavior or 

 determining their identity, or both. Such a study may be regarded as 

 including isolation methods, methods for the cultivation and the storage 

 of various kinds of bacteria, microscopic study of pure cultures either 

 stained or unstained, determination of cultural characteristics of an 

 organism, a study of its physiological characteristics, the chemical 

 methods necessary in making the last-mentioned study, the determina- 

 tion of pathogenicity and study of pathological effects, the serological 

 characterisics of an organism when used as a means of description. 



It is clear from such a statement that pure culture study of bacteria is 

 fairly comprehensive but that there are many fields of bacteriological 

 technic not included within it, e.g., methods for the enumeration of bac- 

 teria in their natural habitats, the diagnosis of disease and many other 

 phases of medical bacteriology, methods employed in the study of food spoil- 

 age and controlling the processes of fermentation, etc. Such a list might 

 be extended almost indefinitely, for the field of pure culture study, although 

 fairly broad, is actually a small part, though basic, of bacteriological technic. 



The scope of the present manual has been widened to include viro- 

 logical methods and procedures for the maintenance and preservation of 

 bacteria, and it may in the future be expanded to include methods for 

 yeasts and molds. Nevertheless its subject matter still does not cover 

 those topics listed in the preceding paragraph. 



RELATION TO TAXONOMY 



Clearly, one of the objects of pure culture study is to determine the 

 identity of any bacterial culture under investigation. This brings the 



