STUDIES UPON AGGLUTINATIO>f 65 



in neutral broth with Bad. iyphosiim and Bad. paratyphosum 

 A; this effect is less noticeable in cultures of Bad. paratyphosum 

 B, Bad. dysentcriae and Bad. coli, but the agglutinating power of 

 these organisms is very weak in alkaline media. Alkaline media 

 are therefore not suitable for the agglutination test with cultures 

 of these bacteria. 



5. Agar cultures emulsified with 0.85 per cent salt solution or 

 neutral broth are almost equal in susceptibility to agglutination, 

 but certain strains have a tendencj^ to spontaneous agglutina- 

 tion in broth medium; therefore salt solution is better. 



6. As to the effect of sodium chlorid on agglutination reactions 

 I could find no difference in the degree of agglutination reaction 

 when using strong or weak solutions of sodium chlorid; only 

 traces are necessary for agglutination. 



7. Glucose broth cultures of Bad. paratyphosum A and B and 

 Bad. coli showed a tendency to spontaneous agglutination; 

 Bad. typhosum showed weaker specific agglutination in glucose 

 broth, but stronger than in pepton water, only occasionally show- 

 ing spontaneous agglutination. The dysentery group yielded 

 weaker agglutination with glucose broth cultures than with 

 plain broth, pepton water and agar cultures. 



Pepton water cultures in general show a slight tendency to 

 spontaneous agglutination, when non-spontaneous agglutinating 

 bacilli are growTi therein. This spontaneous agglutination is 

 difficult to prevent even when formalin is used and the specific 

 agglutination reactions of Bad. typhosum, Bad. paratyphosum 

 A and B and Bad. coli are weaker than in plain broth or glucose 

 broth. On the other hand the dj^sentery group j-ielded stronger 

 specific agglutination reactions in this medium than in glucose 

 broth. 



Agar cultures showed much weaker agglutination than broth 

 and pepton water cultures. 



In general, plain broth cultures gave the best results. 



8. Susceptibility of most cultures to agglutination decreases 

 with age ; eighteen to twenty-four hours cultures were found best 

 suited for agglutination tests. 



J017BNA1. or BACTERIOLOOT, VOL. TU, NO. 



