PART II. 



SPECIAL BACTERIOLOGY. 



CHAPTER I. 



NON-PATHOGENIC BACTERIA. 



Special Bacteriology. Under this head the chief character- 

 istics of individual bacteria will be detailed, pathogenic and non- 

 pathogenic being the main divisions. It is usual to describe the 

 non-pathogenic first. 



Non-Pathogenic Bacteria. We can give but a few of the more 

 important varieties. 



Bacillus Prodigiosus. (Ehrenberg.) This bacillus, formerly 

 called a micrococcus, is very common, and one of the first 

 noticed, because of the lively red color it forms on vegetables 

 and starchy substances. "The bleeding host," miracles being 

 due to it. 



Form. Short rods, often in filaments, without spores. 



Immobile. Has no automatic movements. 



Facultative ancerobic, that is, it can grow without air ; but 

 the pigment requires oxygen to show itself. 



Growth. Gelatine. Liquefy rapidly. 



Colonies. At first white, round points with smooth edge 

 appearing brown under microscope, but soon changing to red. 



Stab Cultures. The pigment develops on the surface, the 

 growth occurring all along the line. 



Potato is well suited to the growth, the pigment developing 

 after twelve hours. Agar and blood serum growths do well. 



Temperature. Grows best at 25 C. 



Varieties. By exposure to heat of brood-oven during several 

 generations the power to produce pigment can be temporarily 

 abolished. 



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