Micro-organisms of M \n.i. Sap 547 



B. pyocyaneus < several strains i 

 Bact. syncyaneum. 

 B. viridans. 



Mis results may be summarized as follows: All fluores 

 cent bacteria show in alkaline gelatin, first a sky blue, later a 

 moss green fluorescence and, accompanying' the latter, a yellow- 

 ing of the substratum. Old cultures with the exception of 

 those of B. fluorescens putridus are orange-red with dark green 

 fluorescence. All these colors are due to one yellow pigment. 

 When an acid producer and a fluorescent organism are culti- 

 vated together the yellow pigment is formed normally, but there 

 is no fluorescence. The green fluorescence in every case is 

 caused by the action of the ammonia produced. Calcium chlo- 

 rid is unessential for the formation of the pigment, but mag- 

 nesium sulphate and potassium phosphate are of the greatest 

 importance. Bact. syncyam um forms two pigments, a fluores- 

 cent one, and a steel-blue one. 



Jordan (14) worked with the following specie-: 



B. fluorescens albus. 



B. fluorescens tenuis. 



B. fluorescens mesentericus. 



B. fluorescens putridus. 



B. fluorescens liquefaciens. 



B. viridans. 

 He summarizes his results as follows: 

 "Both sulphur and phosphorus are essential to pigment 

 formation but the nature of the base associated with these ele- 

 ments is not important. Other things being equal the presence 

 of the methyl or methylene group is coincident with superior 

 nutritive value and fluorescigenic power. Acid in the medium 

 not merely conceals the existence of the substance to which the 

 color is due but interferes with those vital activities of the bacilli 

 which in an alkaline medium lead to the production of that sub- 

 stance. An excess of substance favorable to growth and pig- 

 ment formation checks the latter though the former may be 



