165 



Table IV. 



B. fluorescens. B. typhosus growth. 



No. 29 Absent. 



No. 469 Absent. 



No. 502 Present. 



No. 31 Present. 



The active substance is not destroyed at the temperature of live 

 steam under fifteen pounds pressure for fifteen minutes. 



CONCIA'SIONS. 



The specific antagonism of Ii. fluorescens for B. typhosus is due to a 

 substance secreted by the first named organism. 



Tins antagonism is not characteristic of all B. fluorescens cultures. 

 There seems to be a correlation between the intensity of the color and this 

 property. 



The action is bactericidal. 



/i. fluorescens cultures with slight pigment production do not prevent 

 the growth of B. typhosus. 



The metabolic substances must reach a certain concentration before 

 they become effective. 



The toxic substances secreted by li. fluorescens have the following 

 properties : 



1. They are thermo-stabile. 



2. They are diffusible through a collodion sac. 



Although the growth of B. fluoresce))* in milk would suggest a digestive 

 process, the typhoid bacilli are not agglutinated when grown in a sterilized 

 liltrate of the first named organism. 



