QUALITATIVE BACTERIOLOGICAL ANALYSIS. 17.5 



that some of these bacilli may become temporarily susceptible 

 to agglutination by a highly dilute anti-typhoid serum. 



Experiments with B. fluorescens liquefaciens and B. fhiorescens 

 putridus have shown that the limit of the dilution of anti-typhoid 

 serum which agglutinates these bacilli is about 1100. 



Coliform organisms which reacted strongly to dilute anti- 

 typhoid serum, have been recently isolated from water-supplies 

 by C. Sternberg. One organism was completely agglutinated 

 by serum diluted 11400, and another by serum diluted 1600. 

 A stronger specimen of anti-typhoid serum which completely 

 agglutinated the B. typhosus, when diluted 1-10,000, did not 

 agglutinate the coliform organisms in a dilution above 1-5000. 



It thus becomes evident that to bring out the specific re- 

 action it is necessary to dilute the serum from the immunised 

 animal. This opens up the difficult question as to what dilu- 

 tion is to be considered necessary. 



Many bacteriologists believe that the B. typhosus, no matter 

 from what source it is obtained, will always react in the same 

 way to the same serum. Biberstein working with ten different 

 cultures, Bensaude and Achard with twenty different cultures, 

 and Widal with twenty-six cultures, found no difference in 

 the agglutination of the different cultures with anti-typhoid 

 serum. 



Jatta also failed to detect any difference in his cultures which 

 had been grown on favourable media for periods varying from 

 some months to many years. 



Kolle, however, stated that the agglutination produced by a 

 serum was inversely proportional to the virulence of the bacilli. 

 Gruber advised that a culture of little virulence should be taken 

 for the diagnosis of a serum, because such a bacillus was sensitive 

 to its action. He also thought that by means of a serum, the 

 agglutinating action of which had been exactly estimated, it 

 was possible to decide as to the virulence of a culture. Mills 

 also found that the susceptibility of a bacillus to agglutination 

 was inversely proportional to its virulence. 



My own experiments showed distinct differences in cultures 

 from different sources. As all the races were tested in the same 

 manner with the same serum the results are perfectly com- 

 parable. At the same time the virulence of these cultures, when 



