GENUS BACILLUS 



351 



on a rosy color, which is often marked only in the upper por- 

 tion, forming a thin superficial layer. Old cultures are 

 slightly viscid. 



Milk. It causes coagulation of the casein, without pro- 

 ducing other changes. The coagulum according to Hueppe 

 may later dissolve. 



Life conditions and properties. The most interesting 

 peculiarity of B. prodigiosus is the production of coloring 

 matter. The pigment is formed only in the presence of oxy- 

 gen, the colonies grown in the depths of gelatin or beneath a 

 layer of oil remaining white. The coloring matter is insoluble 



Fig. 71. 



Fig. 72. 



Fig. 71. Bacillus vulgaris. Agar culture 36 hours old. X 510. 

 (Hauser). 



Fig. 72. Bacillus vulgaris showing flagella from agar culture 12 

 hours old (Hauser). X 700. 



in water and slightly soluble in alcohol and ether. Light very 

 quickly decolorizes the alcoholic solutions, but if they are 

 kept in the dark, they will retain their color for years. 



Pathogenesis. This bacillus does not appear to possess 

 pathogenic properties. 



