BACILLUS PRODIGIOSUS. 



BY C. M. BROOMALL. 



Bacillus prodigiosus occurs usually as ^z% shaped, non- 

 motile cells, about one micron in diameter ; sometimes they 

 are distinctly rod-shaped ; sometimes they are found in long 

 chains. The cells are colorless, the red color being due to a 

 pigment which appears in the surrounding medium. This 

 pigment is little or not at all soluble in water, but freely sol- 

 uble in alcohol. The bacillus grows well on gelatine plates, 

 potatoes, cooked meat, in milk, etc. Probably the best 

 medium, however, for its culture is moist, sterilized bread. 

 The writer has many times wondered at the vigor of its 

 growth on moist bread in cases where, despite the fact that as 

 a result of contamination a mass of bacterial life of all kinds 

 had almost obliterated the signs of Bacillus prodigiostis, the 

 latter survived and remained in control of the situation. 

 The faculty of the bacillus for growing on bread and similar 

 farinaceous compounds is said to account for the appearance of 

 " Blood on the Host," a phenomenon referred to in church 

 history. Indeed, the resemblance of a colony of Bacillus pro- 

 digiosus to a mass of blood is startling. When fresh, the 

 colony appears covered with red drops as intense in color as 

 arterial blood. Later, as the colony loses vigor, or becomes 

 contaminated with other bacteria, it takes on the darker red 

 of clotted blood. 



Bacillus prodigiosus is a saproph^-tic organism, and in 

 pure culture is probably harmless to man. The colonies pro- 

 duce no odor, and the energies of the bacterium seem to be 

 turned principally to the production of the red pigment. 

 Under certain conditions its color producing faculty seems to 

 be held in abeyance, the protoplasmic energy being devoted 

 principally to the production of lactic acid. The ordinary- 

 growth of the bacillus produces acid sufficient to curdle milk. 

 It is claimed by some that it can only produce lactic acid in 

 the presence of some form of sugar. 



