lO BROOMALL : 



What the coloring matter produced by Bacillus prodigiostis 

 is seems not to be known. Indeed, the students of the subject 

 do not seem yet to have finally settled the question whether it 

 is secreted within the cell or produced in some way in the sur- 

 rounding medium. The latter, however, is probably the more 

 current belief. Light and darkness, in the experience of the 

 writer, seem to have little effect on the intensity of the color 

 or vigor of the colony, except in so far as they affect the 

 growth of interfering bacteria. 



If an5'thing, darkness seems to favor the more vigorous 

 growth. The writer, in two instances, while growing com- 

 parison colonies in light and darkness, has been unfortunate 

 in losing the "light" colon3^ In each case, however, con- 

 tamination by other bacteria was pronounced and may have 

 been the real cause of the trouble. 



The purer and more vigorous the growth of the bacillus, 

 the brighter red does the color seem to be. As the colony 

 wanes in vigor, owing to auto-intoxication, exhaustion 

 of the medium, contamination, or some other cause, the 

 color becomes darker red, and finally strongly resembles clot- 

 ted blood. In cases of colonies infected by other victorious 

 bacteria, the dark red color gradually turns to a grey or some 

 unpronounced color. Even in this case, however, the bacillus 

 can be easily resuscitated by a few successive inoculations on 

 sterilized bread. 



As stated, Bacillus prodio^iosus is non-pathogenic, although 

 it has been pointed out by Fehleisen and Coley that its growth 

 in conjunction with the strepticoccus of erysipelas greatly 

 increases the virulence of the latter. Certain other sapro- 

 phytic bacteria which flourish at bodily temperature have the 

 same effect upon the strepticoccus. 



Despite the above example of the pernicious effect of bad 

 associations, Bacillus prodioiosus is not only harmless to man, 

 but the attempt has even been made to make practical use of 

 it. Thus, in examining the bacterial efficiency of water 

 supply filters, the introduction of Bacillus prodigiosus or 



