162 



was isolated from the Mississippi River and was labeled B. fluoresceins 

 liquet miens.* No. 502 came from the University of Vermont and was 

 labeled B. fluoresceins tenuis. 



When grown on various media these cultures gave the following re- 

 actions : 



Table I. 



Media. 



No. 29. 



L. milk Digested. 



Lac. broth No gas. 



Nitrate broth. Nitrates 



reduced. 

 Pep. broth No indol. 



Gelatin. 



Liquefied. 



No. 469. 

 Digested. 

 No gas. 

 Nitrates 



reduced. 

 No indol. 

 Liquefied. 



No. 502. 

 No reaction. 

 No gas. 

 Nitrates 



reduced. 

 No indol. 



No. 31. 

 No reaction. 



20%. 

 Nitrates 



reduced. 

 No indol. 



Not liquefied. Not liquefied, t 



The only appreciable differences between these two groups of cultures 

 lie in the litmus milk and gelatin reactions. This would suggest that the 

 process was one of digestion, but by direct microscopic methods it could 

 not be determined. When B. typhosus was mounted in some of the steril- 

 ized B. fluoresceins filtrate and examined under the microscope, no aggluti- 

 nation was observed. 



When the two organisms B. fluorescens and B. typhosus, are grown 

 in parallel streaks on solid media, it is found that there always remains 

 a zone between the two where no growth occurs, B. fluorescens gives off a 

 pigment which facilitates the study of this phenomenon by microscopic 

 methods. B. typhosus never trespasses over the green border line put 

 up by B. fluorescens. This suggested a further study of the two organ- 

 isms in liquid media. The method was practically the same as that used by 

 W. D. Frost in his work on 'The Antagonism Exhibited by Certain Sapro- 

 phytic Bacteria against the B. Typhosus Gaffky" and described in his 

 article on "Collodion Sacs."f 



A gelatin capsule is fastened onto the end of a glass tube by heating the 

 tube slightly before applying the capsule. The capsule and part • of the 

 tube are then dipped into collodion and allowed to harden. After a few dip- 

 pings the sac is strong enough to stand without the aid of the gelatin. 

 The gelatin is dissolved by means of hot water and the sac is ready for 

 use. The sac is filled with nutrient broth and inserted into a flask con- 



*Although labeled B. f. liquefaciens, No. 31 failed to liquefy gelatin. 

 tReports and Papers of the Am. Pub. Health Assn. Vol. 28. 



