CHAPTER XI 



STUDY OF BACTERIAL CULTURES 



SPECIES of bacteria are frequently separable from each other 

 on the basis of differences in cultural characters alone. It is, 

 therefore, important that careful descriptions should be kept of 

 the cultural characteristics of each of the species. For assistance 

 in such descriptions the Society of American Bacteriologists has 

 adopted a standard descriptive chart from which the following are 



adapted : 



CULTURAL CHARACTERS 



Agar Stroke. This is prepared by drawing an inoculated needle 

 from the base to the top of the slanted surface of an agar tube 

 that has solidified in the sloping position. In this culture are to 



Fig. 57. Types of growth on agar slants. 



be noted the abundance, form, elevation, luster, surface, and optical 

 characters of the growth, its pigment production, odor, consistency, 

 and any changes that have occurred in the medium. 



Potato. The potato is inoculated and the growth character- 

 istics studied in the same manner as the agar stroke, 

 no 



