PART II 

 SPECIAL BACTERIOLOGY 



CHAPTER XVII 

 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. The division is not a 

 strict one, under certain conditions bacteria ordinarily non- 

 pathogenic may become pathogenic. 



Non-pathogenic Bacteria. The list of non-pathogenic 

 bacteria is a long one, and is being added to continually. 



Bacillus Prodigiosus (Ehrenberg) . This bacillus, for- 

 merly called micrococcus, is very common, and one of the 

 first noticed, because of the brilliant red pigment it forms 

 on vegetables and starchy substances. "The bleeding host" 

 miracles are said to have been due to it. 



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



Immobile. Has no automatic movements. 



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

 the pigment requires oxygen to show itself. 



Growth. Gelatin. Liquefy rapidly. 



Colonies. At first white, round points with smooth edge, 

 appearing brown under microscope, but soon changing to red. 



Stab-cultures. Red 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. A gar and blood-serum well suited for growth. 



Temperature. Grows best at 25 C. 



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