Bactericidal Action of Rabbit Bile. 35 



tococcus. Our next step was to test various strains of streptococci 

 from human and animal sources, these strains having been classi- 

 fied according to their hemolytic and sugar fermenting properties. 



The results may be briefly summarized, by dividing the or- 

 ganisms into three groups, at least two of which are apparently 

 clear cut. 



I. All those hemolytic non-mannite fermenting Streptococci 

 which fall, by Holman's classification, into the Streptococcus 

 pyogenes group, were killed by rabbit bile, 1/50 of 1 c.c. of bile, 

 or less being sufficient to kill 0.1 c.c. of a 24-hr. serum broth culture. 

 About twenty cultures of this type were tested. 



II. All non-hemolytic Streptococci, whether of human or bovine 

 origin, were unaffected by rabbit bile. 



III. Hemolytic, mannite fermenting streptococci are almost 

 always unaffected by rabbit bile. In a group of thirty or more 

 of such strains tested, only two were killed by bile. 



Since this bactericidal power of rabbit bile is undiminished by 

 sterilization, attempts were made, by fractioning the bile, to 

 determine, if possible, what constituent of rabbit bile is respon- 

 sible for this highly selective bactericidal action. 



Bile was dried with sand, to give greater surface for extraction, 

 and the resulting mixture ground and treated with absolute 

 alcohol, thus precipitating the proteins. The resulting filtrate 

 was evaporated to dryness and then resuspended in broth to the 

 original volume of the bile. This was sterilized and tested for its 

 bactericidal power, which was found to be undiminished. Next, 

 a portion of this alcoholic extract was treated with absolute 

 ether, causing a further precipitate. Both filtrate and precipitate 

 were dried and resuspended in broth, and tested as before. It 

 was found that only the, precipitate contained this bactericidal 

 substance. It may be of interest here to note that Neufeld found 

 that the pneumococcus dissolving substance of bile was also 

 located in this fraction. However he found this to be true of 

 various types of bile, whereas the phenomenon here described 

 only occurs with rabbit bile, and is a bactericidal and not a lytic 

 process, since the bacterial bodies are visibly intact even after 

 48 hours. 



On treating the alcohol soluble fraction with acetone, both 



