162 
was isolated from the Mississippi River and was labeled B. fluorescens 
liquefaciens.* No. 502 came from the University of Vermont and was 
labeled B. fluorescens tenuis. 
When grown on yarious media these cultures gave the following re- 
actions: 
TABLE I. 
Media. No. 29. No. 469. No. 502. No. 31. 
L. milk Digested. Digested. No reaction. No reaction. 
Lac. broth No gas. No gas. No gas. 20%. 
Nitrate broth. Nitrates Nitrates Nitrates Nitrates 
reduced. reduced. reduced. reduced. 
Pep. broth No indol. No indol. No indol. No indol. 
Gelatin. Liquefied. Liquefied. 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. fluorescens 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.’+ 
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. 
+Reports and Papers of the Am. Pub. Health Assn. Vol. 28. 
